Fabrication and installation of wire harnesses. Harness installation. Purpose and classification. Harness production: templates, processing, layout and knitting, spare wires, installation and fastening, protection, marking, quality control. Specification object

Intrablock wiring harnesses lay out and knit, observing all the above rules. Wire bundles are not allowed to tangle, except as specifically indicated in the technological map. Crossing of wires is possible only at the points of their exit from the bundle and with a cross-shaped arrangement of branches,

For laying out the bundles, prepared wires with stripped and sealed ends, as well as wires from coils, are used. When laying out and knitting the bundles, be careful not to damage the insulation of the wires and not to break their bare ends. The knitting of the bundle with a thread is carried out by means of a metal shuttle with a pre-wound thread or a curved needle.

When laying the bundle in the device, the ends of all wires are carefully spread with tweezers in accordance with the location of the contact petals to which they must be connected. Passing the branches of the bundle and individual wires through the holes of the rubber bushings, be careful not to damage the termination of the ends of the insulation and the marking.

Sections of the bundle with a length of less than 150 mm are held quite securely by branch wires that are connected to the contact petals of the parts. Sections of the tourniquet, the length of which

exceeds 150 mm, as well as the coaxial cables of the RK are attached to the chassis 2 (Fig. 2) metal

with brackets 4, curved according to the shape of the section.

Harness or cable. At the attachment point, the tourniquet is wrapped with a gasket 3 made of insulating cardboard or PVC, the width of which is 3-5 mm more than the width of the bracket, and the thickness is not less than 0.5 mm.

The layout and knitting of interblock bundles are made in such a way that the relative position of the wires in the bundle remains unchanged along the entire length. To do this, use a fixed comb 2 (Fig. 3), which is a metal plate with holes, the number and location of which corresponds to the number and position of the contacts of the largest plug

connector. Wires 3, unwound from rack 4 and passed through the holes of the comb, are tied into a bundle as the entire bundle is pulled through the fixed comb or moved away from the fixed ends of the wires. Then, using a cutting device, the wires collected in a bundle are cut off.

When laying out and knitting interblock bundles, a constant mutual arrangement of wires is ensured due to the strong tension of the wire when it is wound on racks, the same arrangement of turns

on both racks and accuracy of knitting. Shown in fig. Method 4 is applicable for knitting bundles of wires of the same brand and one section, taken from one bay. Interblock bundles are knitted with waxed linen thread using a shuttle. Loops are applied at intervals approximately equal to 50 mm. For inter-block harnesses with 14 or less wires, apply

prefabricated multi-core KMV cables in a plastic sheath, consisting of MGShV wires with multi-colored insulation.

In accordance with the instructions in the drawings and technological maps, the ends of the interconnect bundles are sometimes wrapped with a keeper tape. The tape is wound with tension, and each subsequent turn should overlap half the width of the previous one (Fig. 5). One end of the p tape is passed between the wires to the other side of the bundle, pulled along the bundle until it stops at the beginning of its tying with a thread, bent in the direction of the winding and placed under the first turn of the tape. Having finished the winding, the second end of the tape is cut off and fixed with a linen thread. After that, the tape is impregnated with BF-6 glue.

Interblock harnesses are enclosed in a protective metal braid. Depending on the length of the tow, this operation is performed either by pushing it into the braid manually, or by pulling it through with a tool. With manual pushing, the end and end of the bundle are wrapped insulating tape or enclosed in a metal braid of the appropriate diameter, which is then tightly tightened with a tourniquet.

When pulling the harness 4 (Fig. 6) through the braid / by means of a special device consisting of a metal rod 2 and a segment of the braid 3 of the appropriate diameter attached to it, the braid 1 is pre-expanded, and after putting it on the end of the bundle, it is tightly fitted.

Usually, installation wires laid in one direction are tied into a common bundle with cotton or linen threads. Harnessed installation is distinguished by increased mechanical strength, reduces the spread of the circuit's own capacitance and reduces the laboriousness of installation operations.

A harness sample is made at the design stage of the device. The following procedure for working out the tourniquet is recommended. On a chassis fully assembled and ready for mounting according to wiring diagram and table field connections lay out the wires. The ends of the wires are fixed on the contact petals and marked. The layout of the wires is carried out in such a way that the finished harness does not lie on the fasteners (nuts, screws, brackets, etc.) and, if possible, does not impede access to them; in addition, the insulation of the wire harness must not touch the contact lugs of closely spaced parts.

The insulation of the wires in the places where the harness passes through the holes in the chassis and screens is protected with PVC pipes, gaskets, as well as special rubber bushings (caps) and insulators.

First, short wires are laid, and lastly, the longest ones so that the latter form the front side of the bundle. Shielded wires are laid in the middle of the bundle, not enclosed in PVC tubes. If, according to the specifications, spare wires are provided in the bundle, they are laid on top for the greatest length of the bundle.

Be sure to provide a margin of wire along the length for fastening (20-25 mm at both ends) and the same margin for re-fastening the ends of the wires in case of breaks. Thus, in addition to the distance between the wire connection points, another 40-50 mm. Before fixing the second end, measure the length of the wire, and the results are entered in the table of field connections.

After laying out the harness, the wires are tied with a strong thread using a curved needle; loops should be knitted with tension at regular intervals (no more than 20 mm), a also in places where the wires branch off (Fig. 1.). Fasten the beginning to the end of the thread, as shown in Fig. 2. When the harness is knitted, it is removed from the device and corrected for flat surface; the bundle branches located in different planes are bent 90° into the plane of the main part of the bundle.

Fig.1. Wiring and harness: 1 - wire, 2 - harness, 3 - branch of the harness, 4 - thread

Fig.2. Fastening the thread on the tourniquet: 1 - thread, 2 - tourniquet

Then the tourniquet is placed on a sheet of drawing paper face down and copied in full size. A sketch of the bundle is shown in Fig. 3, where the dots indicate the studs; serial numbers of wires are given in circles; abbreviated letter designations KR, ZL, etc. indicate the color of the wire (red, green); Roman numerals indicate the numbers of the bundle branches.

A sketch of the harness is used to make an experimental template, which is a sheet of plywood with a harness drawn on it and studs driven in in the right places (Fig. 4). An experimental harness is knitted according to the template, and the layout of the wires on the template starts with spare and long working wires and ends with short ones, i.e., the reverse order of the wire layout and the reverse image of the bundle are used. This is done to give the tourniquet a neater look: the knots made on the tourniquet will not be noticeable after it is laid in the device.

An experienced tourniquet is checked by laying it on the chassis of the device, the inaccuracies are identified and corrected. Corrections are made to the sketch of the bundle and the table of field connections. The working template is made according to the corrected sketch of the tourniquet.

The Vector company is ready to offer a range of services for processing wires, assembling and manufacturing bundles, crimping contacts, lugs and terminals. To do this, the company has all the necessary modern high-performance equipment, a professional workforce with years of experience production of wires and harnesses of any complexity.

For making harnesses and wire processing a Kappa 220 wire-cutting and stripping machine is used, capable of processing sections from 0.05 to 6.0 mm2.

The possibility of automated processing of a wide range of wires and cables is provided:

automotive wires: PVA, PVAM;
mounting wires: NV, MGTF, MGSHV;
installation wires: PV1, PV3;
flat tape: LV, LAN;
power cords: ShVP, ShVVP.

It is also possible to strip the already cut wire on the machine or manually on the COSMIC 32M semi-automatic machine.

Vector has a Mecal TT semi-automatic press, which is extremely compact and lightweight and provides a stable crimping height. Standard stroke 40mm. Height working area equal to 135.8 mm, which allows the use of all standard types of mini applicators.

This makes it possible to crimp lugs on wires for almost all existing types of connectors (BLS contacts, HPB (for MHU, PHU), HU, CHU, Mini-fit (MF - F, MF - M), PW, PW 10, MU, MDU , 794606-1 and others). There is also a large list of tools for manual crimping of connectors, lugs and so on.

The following consumables are supported in the warehouse:

PVC tube, fluoroplastic and corrugated
Heat shrink tubing 2:1;
Adhesive heat shrink tube;
Mounting wires NV, MGSHV, MGTF, PV, PVAM;
Network and signal cables
Cable lugs and contacts
Standard imported connectors
Insulating materials (varnished fabric, textolite, fluoroplast and others)

The company "Vector" is also ready to offer a range of services:

Technological possibilities and limitations

Wire types	stranded stranded and solid copper, single wires
Types of insulation	polyvinyl chloride, bonded polyethylene, Teflon (TFE), Tefzel (ETFE), Kynar (PVDF), silicone rubber, fiberglass, Nylon, Mylar, Vulkene, neoprene, Hypalon, other wound or embossed insulation
Min. section
Max. section
Min. wire length
Max. wire length	999.5 meters
Min. stripping length
Max. stripping length	full stripping: 9 mm on stranded wire, 40 mm on solid wire
Half-sweep
Lot size	not limited
Max. performance*	10000 wires per hour

*Performance depends on wire type, insulation, wire length, stripping length, wire size.

diagram, layout of the node or device in which the harness will be installed, and the mounting table of connections. On the marked template, the wires are laid out, and then they are knitted into a bundle (Fig. 87). Depending on the design of the device, the bundles are flat or voluminous.

When laying out, the ends of the wires are cut along the transverse marks, marked and fixed. Laying the wires on the template starts with spare and long working wires and ends with the shortest wires. The shielded wires included in the bundle are wrapped with keeper tape and placed inside the bundle or in an insulating tube.

The harness is knitted in one direction with cotton thread No. 00 or linen No. 9.5/5. For manual knitting, a device is used (Fig. 88, a), in the body 4 which the coil is inserted 3 with threads. Lids 5 and 2 serve to center the coil 3. In the top cover 5 there is an eyelet to give the thread a certain direction, and a hook is attached to the bottom cover 1.

Rice. 87. Template for laying and knitting harnesses:

1 - a hairpin for fixing the end of the wire, 2 - wires, 3 ■

template (removable sheet), 4 - stud for laying wires, 5 ■

base

To facilitate the winding of the thread from the spool, a slot and an outlet for the outer end of the wound spool are provided in the body. The work of the device is carried out in a certain sequence. First, a wound coil is inserted into the body of the device, the upper end of which is inserted into the slot of the body. Next, the lid is closed and the end of the thread is threaded through the eyelet.

The harness is knitted according to the loop formation scheme. It takes 0.5-1 s to tie one knot. To perform the operation, it is enough to take the thread, as shown in Fig. 88, b, hook the loop with a hook, stretch it under the tourniquet and thread the device through two loops,

Rice. 88. Device for manual knitting of harnesses (a) and the sequence of loop formation (b)

pulling the thread. At the moment of tightening the knot, the thread passing through the body must be pressed with a finger to its surface. This device improves the quality of knitting harnesses and reduces the complexity of their knitting by 15-20 times. Recommended knitting methods are shown in fig. 89.

When knitting a harness, it is recommended to knit loops with tension at regular intervals (no more than 50 mm), as well as in places where wires branch off. The knitting step of the loops is set by the designer, depending on the diameter of the bundle.

After knitting the wires into a bundle, their ends are terminated. In this case, all ends of the wires are marked according to the wiring diagram. Then they control the correct layout of the wires with a dial tone. In the case of using electrified templates for making harnesses, continuity can be omitted.

The control of complex harnesses is carried out on special semi-automatic stands according to a given program. The harness on the panel of the stand is fixed manually, and the correct layout of the wires and the resistance of their insulation are controlled automatically.

First, check for compliance with the electrical wiring diagrams (checking the correct layout of the wires). At the same time, the required voltage is sequentially applied to one of the ends of the wire under test and the appearance of this voltage in all other wires of the bundle electrically connected to the wire under test is noted. In addition, note the absence of voltage in the wires of the bundle, which are not electrically connected to the wire under test. All information about the control is issued automatically in the form of coded holes on a punched tape or as a record on a tape with digital and alphabetic designations.

When monitoring the insulation resistance of wires, the stand automatically supplies constant voltage to electrically isolated wires (circuits) in sequence, while fixing the insulation resistance.

If necessary, the harness is protected with insulating tapes or a shielding braid. Finished harnesses are laid according to the wiring diagram and the drawing of the device. Simultaneously with laying, the ends of the wires of the bundle are bred to the corresponding places of the device circuit and soldered. At the same time, it is necessary that individual wires do not obscure the markings and the inscriptions on the value of the ratings on the parts.

When laying the harnesses in the device, care must be taken to avoid breakage. and breakage of conductive cores of wires and conclusions of mounted radio components, as well as short circuit of bare conductive places. Inside the device, the harness is attached to the chassis or walls with metal brackets (Fig. 90), under which

Rice. 90. Attaching harnesses:

/ - harness, 2 - insulation (tape, tube), 3 - bracket (double-sided)

pre-enclose insulating materials from polyvinyl chloride, varnished fabric or pressboard. The edges of the pads protrude from under staples not less than 5 mm. Structurally, the brackets are double-sided (fixed with two screws) and one-sided (fixed with one screw). The rigidity of the mounting brackets, especially single-sided ones, must be sufficient to prevent them from bending or deforming when attached to the chassis together with the harness.

When passing unshielded (and, if necessary, and shielded) bundles from one unit of the device in the other through the wall

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1. Technical characteristics of the production object

Specification production facility for which this technological process, is the manufacture of harnesses.

General information about harnesses and their manufacturing technology

Harness installation is an electrical installation of EVA units using volumetric insulated wires, combined into a bundle.

In order to keep transport losses as low as possible, metals with high electrical conductivity are mainly used. In the case of the location of the conductor, the cross section of the conductor is determined by the maximum allowable current density. An electrical line usually consists of several wires or strands, but often strips and rails as well, depending on the application. The main materials used are copper and aluminum, as they have particularly good electrical conductivity. Electric cables are the nervous system of the century and connect houses, cities and countries.

The harness designs are determined by the structural features of the frames and the requirements for the maintenance and repair of equipment. Harnesses are divided into interblock and intrablock, which, in turn, are divided into flat, volumetric, with movable branches.

They are also distinguished by the degree of complexity: the number of branches and closed branches. Harness installation is carried out using mounting wires and cables of various types and purposes. Wire insulation can be fibrous from kapron threads (MShDL, MGSH, MGSHD) or fiberglass (MGSL, MGSLE); polyvinyl chloride (PMV, MGV) and fibrous polyvinylchloride (MShV, MGSHV, LPBL), plastic in the form of a polyvinyl chloride shell (MKSH, MPKSH); rubber (LPRGS, PRP, APRF, PRG) and fluoroplastic (MGTF). The choice of insulation is determined by the electrical voltage and operating conditions of the equipment.

Electronics Solutions

The pipes can be laid in the ground and operated on electric masts or on the seabed. The characteristics of an electric line are described by linear gaskets, wave resistance, and dielectric strength. Line resistance is affected by the cross-sectional area and heat in the line. Further decisive properties of the electrical cable are the maximum bending radius, tensile strength and heat resistance of the insulating materials.

The term "electricity" essentially consists of simple, uncontrolled circuits with mechanical switches, lamps, and similar electrical components. The term "electricity", which is mainly associated with the installation of electrical appliances in a home or vehicle, is called "electricity". In contrast, electronics uses different, usually very small, electronic components.

At normal temperature and humidity, wires with fibrous or PVC insulation are used, at elevated temperatures and humidity - with fiberglass or fluoroplast insulation.

If it is necessary to protect against external electrostatic fields, the installation is carried out with shielded wires and cables with mandatory grounding of each shield.

The cable sheath protects the cable from external mechanical, electrical and chemical stresses, the insulation being a component of the cable sheath. Using a special wire braid, the cables can also be shielded from external electromagnetic interference. In the case of wire insulation, a particularly high electrical resistivity occurs because it must also withstand overvoltages. Rubber is used as cable insulation in areas with thermal, mechanical and chemical stress.

It has very good chemical resistance, wear resistance and provides high flexibility for cables. An electrical switch is understood to mean an assembly that can create an electrically conductive connection using two electrically conductive components or semiconductor components. This happens in the ideal case on an all-or-nothing basis. If the conductive components have not been contacted, no current should flow. Thus, the switch has two states: "Open" and "Closed".

Part of the installation wires, especially those with rubber insulation, are supplied with tinned conductors. This preserves the electrical resistance and mechanical strength of the copper wire, located in rubber or vulcanized rubber, and speeds up the process of preparing wires for mounting and soldering.

When designing, the tolerances for the harness parameters can be determined analytically. When calculating the dimensional chain, they take a wire with a margin for soldering and compensating for bends at contact connections. The deviations of the master link must take into account the tolerances for the geometric dimensions of the frame, the fastening of the bundle, the length of the wires during layout, the installation of technological studs on the template.

In principle, switches can be distinguished by many features. The main functions are actuation type, contact making type, design features or usage characteristics. In addition to environmental conditions, the most important information for the user is the characteristic values, which describe the maximum allowable voltages and currents of the electrical switch. The component must be guaranteed under all operating conditions. In the open state no current must flow and the switch must be insulated safely, in the closed state a correspondingly high current must flow.

The initial development of the harness design is carried out as follows. On the assembled frame lay the wires according to the wiring or circuit diagram. The ends of the wires are marked on both sides with tags indicating the route number (^ -2; 1 -6; 3 -5 etc.), after which their length is measured and the data is entered in the table of field connections.

If the switch is subdivided according to the behavior after operation, basically two types of switches can be distinguished: switches that remain activated and switches that, after being activated, open the contacts independently.

Comparison: copper cable and aluminum cable

Examples of permanent switches. Differentiation of switches by application type. Electric switch. . Application differentiation. Main emergency stop switch emergency switch safety switch repair switch load switch switch switch, etc. Aluminum has about 70% of the electrical conductivity of copper. The cross section of replacing copper cables with aluminum cables is increased by about 60% while the weight is reduced by 35%.

The sketch is used to develop a template and. in particular, to determine the placement of technological studs. An experimental harness is assembled on the template, and after it is installed on the frame, the template is adjusted.

2. Manufacturability analysis

Technological design is called, which, at the lowest cost, is the easiest to manufacture. Technological design should include:

The use of aluminum cables can reach up to 80%. Copper is an important component of electrical cables and wires. Fluctuating raw material prices for copper cable manufacturers provide flexible pricing. On the settlement day, the difference between the settlement copper price and the current day's price is treated as a copper surcharge.

The term "electrical network" is commonly used in almost all vehicles and refers to the entire system of all electrical and electronic components in vehicles. It consists of one or more cable assemblies, cable assemblies and cables, all of which converge in the control system and can interact with each other through system-internal logic. Transfer of information and electrical energy in the vehicle is transmitted by the internal wiring system.

1. The widest possible use of unified assemblies, standardized and normalized parts of the elements of parts;

2. Perhaps a smaller number of parts of the original and complex shape and various names, as well as a greater repeatability of parts of the same name;

3. Creation of parts of a rational form with easily accessible surfaces for processing and sufficient rigidity in order to reduce the labor intensity and cost of the entire product;

Components connected or connected to a wired system. Control units Cables Bus systems Energy storage Generators Sensors Actuators Indicators and lighting Electrical heating elements . Typically, the electrical system is supplied with a 12V supply, and major car manufacturers are planning to switch to 48V in the future to make the electrical system even more efficient. As a result of the increase in the number of consumers in the vehicle, it will be necessary to increase the voltage of the system in the long term.

4. It should be rational to assign the accuracy of the size and class of surface roughness;

5. The presence of basing surfaces on the details;

6. The most rational way to obtain blanks for parts (castings, stampings with sizes and shapes that are as close as possible to finished parts, i.e. providing the highest material utilization and the lowest labor intensity);

Wiring system as a complex system wiring is one of the most complex individual components in a vehicle and is also one of the most expensive due to the high manual production proportion. But the onboard network must also adapt to changing customer requirements and needs. The constant innovative pressure in the automotive industry is demanding a generation of cars that are lighter, drive with reduced energy and at the same time convince the driver with extra comfort and safety.

7. Complete elimination or possibly less use of fitting and fitting work during assembly by manufacturing interchangeable parts and mechanization, automation of assembly work;

8. Simplification of assembly and the possibility of parallel assembly in time and space of individual parts of the product;

9. The design should be easy to assemble and disassemble, as well as provide access to any mechanism for adjustment, lubrication, repair.

Limits must be exceeded. The bus is a cable system and is used to transfer data along a uniform transmission path between different subscribers. Members do not participate in the transfer of data between other members. Buses connected to a bus are often also referred to as nodes. In principle, the bus system is organized in such a way that only one single node sends data to the bus at any time and is processed by another node. To send information to the correct node, identification is done by addressing.

Appeal to electronics

Information can also be transmitted from the override bus. The highest priority is given to the information with the highest address. Thus, despite the huge data transmission in the vehicle, the higher-ranked information is immediately transmitted and processed in an emergency.

The design being developed is technologically advanced, since it provides for:

1. There may be fewer parts of the original and complex shape and various names, as well as a large repeatability of parts of the same name;

2. Creation of rationally shaped parts with easily accessible surfaces for processing and sufficient rigidity in order to reduce the labor intensity and cost of the entire product;

Depending on the application, the following tires are allocated. In addition, a distinction can be made between parallel and serial buses. Serial bus: transfer of data in a row. Reduced cable protection through redundancy Modulation and standardization Enhanced communication options Controlled by diagnostic components. Comparison of bus systems in the automotive sector.

The main task of sensor technology in general is to convert non-electrical measured quantities into electrical signals. Thus, it is necessary to record and evaluate changes in ecological, biological and technical systems, with the result that the evaluation is usually carried out by logic connected to the sensory system. The steadily growing sensor technology in technology is leading to a simultaneously increasing degree of automation. For example, vehicles are equipped with all a large number sensors that form driver assistance systems connected to the electrical system of the vehicle.

3. Simplification of assembly and the possibility of parallel assembly in time and space separate parts products;

4. Complete elimination or possibly less use of fitting and fitting work during assembly by manufacturing interchangeable parts and mechanization, automation of assembly work.

3. Technological route for the manufacture of the tow

The best examples are speed counters, acceleration sensors and distance sensors. Our cable assembly offers you ready-to-connect single wires, cables, cable sets and entire cable trees with plugs, pins or even wire lugs.

Horizontal sectional table for laying out and knitting harnesses of any length

The processing process uses different solutions for connectors from different manufacturers. Both crimping technology, insulation technology, and soldering technology are very common. According to your requirements, the scope of the respective cable trees or connection cables.

The technological route for the manufacture of a bundle is the following sequence of operations:

1. Preparatory operation

2. Equipment

3. Preparation of installation wires

4. Wire layout on the template

5. Knitting a tourniquet

6. Control

4. Detailed description of the main operations

1. Preparatory operation

Processing strands or bundles of cables into extensive cable trees. The implementation exactly matches the requirements of the customer. 100% electrical final inspection. Marking according to customer requirements. Processing multi-core cables of various qualities. Automatic stripping in the process of cutting and winding pipes. Attachment of all common contact systems with crimp control systems.

Armoring of wires with ferrules

Processing flat ribbon cables in mesh sizes from 1.27 to 2.00mm and 2.50mm. For example, in stripping crimping machines or in cutting clamp technology. 100% electrical final inspection with full batch and quality control. Manufacturing exactly according to customer requirements.

2. Equipment

3 . Ppreparation of installation wires

Preparation of installation wires consists of the following operations: dimensional cutting, removal of insulation and termination of wire ends, marking, maintenance and twisting of wires. If the technological process provides for a continuous layout of the wire on the template, then cutting, removing insulation and terminating the ends is carried out after the formation of the bundle.

Manual cutting of wires is performed with simple tools (scissors, wire cutters), determining the length of the wire according to a sample or using a ruler. In mass production, this operation is automated. Universal are machines for measuring cutting and simultaneous removal of insulation from the ends of the wire.

Depending on the type of insulation, various stripping methods are used: , electric firing or thermal softening with subsequent mechanical contraction of the insulation, and certain ways termination of wire ends.

Textile, plastic and film insulation is removed by incision or electric firing. The removal of multilayer insulation has a number of features. So, in the presence of fiberglass, the outer plastic insulation is removed by electric firing, and the inner (fiberglass) is untwisted, twisted and cut off at a distance of 1 mm from the end of the outer insulation. Outer textile braids require stepped cutting of the ends of the wires. For example, between a cotton braid and a residential wire, a section (3-10 mm) of the main PVC or rubber insulation is left. The end of the braid is fixed with glue, an insulating tube or a thread bandage coated with glue.

Stripping of heat-resistant fluoroplastic insulation is carried out by electric firing at an elevated temperature of the filament. This releases toxic gas - fluorine, which must be removed from the working area using a suction system.

The stripping must preserve the quality of the non-removable insulation, exclude a cut or break in the current-carrying conductors and be sufficiently productive. In addition to machines for cutting wires and stripping insulation, special devices have been developed for thermomechanical stripping. Their main working elements are a filament and sponge-knives.

The thread burns through the insulation when the wire is rotated around its axis. Sponges are a support for the wire when burning the insulation, protect it from charring and the thread from mechanical damage, provide insulation together with the thread. The working edges of the jaws have a rounding radius of 0.08 mm and are polished, which will exclude a notch and a break in the current-carrying wires. Insulation stripping devices - can be equipped with a device for connecting to a vacuum system for suction of toxic products of insulation burning. The thermomechanical method allows you to remove insulation in one step from wires with a cross section of 0.07-0.35 mm 2.

Shielded wires and RF coaxial cables are used for installation, having an outer PVC coating on top of the shielding braid. The separation of the coating by a notch is laborious and does not provide a high quality of cutting the ends.

The thermomechanical method allows you to remove the plastic insulation within 2-3 seconds without damaging the braid.

sponge knives , equipped with heaters penetrate the insulation and cover the shielding braid in diameter. The section of insulation inside the jaws heats up and expands, making it easy to remove it by pulling it off the end of the wire.

Further cutting of the ends of the shielded wires is to remove the shielded braid in a certain area. One of the removal methods is a circular cutoff of the braid using a punch-die cutting pair.

The working part of the punch is made in the form of a cone, turning into a sphere, which allows it to move quite easily inside the braid and provides an even cut of the screen end on the sharp edges of the matrix . The method is implemented with the help of devices of various designs, which make it possible to cut off in 3–4 s.

There are other ways to remove the shielding braid: a helical cut with rotating cutters and knives, cutting off the annular thickening of the braid.

To extract the end of the insulated wire through the shielding braid, the core is pulled apart with a sharp tool: the braids and the wire are pulled through the hole formed. The most common tool is a grooved needle, which is inserted from the end of the shielded wire between the braid and the insulated wire. In a certain place, the tip of the needle pushes the braid apart and, using the eye of the needle, pulls out the end of the wire. This operation is performed in 3-4 seconds manually, guiding the needle using simple devices.

Termination of the ends of shielded wires consists in grounding the shields or fixing the end of the braid relative to the wire. Grounding is carried out by attaching the free end of the braid to the elements of the frame, soldering an additional wire, applying a bandage of bare tinned wire, and then soldering it. Soldering points are protected with insulating tubes.

A non-grounded braid is terminated between two insulating tubes, one placed under the screen and the other outside or between layers of insulating tape. The end of the braid is fixed with a thread bandage or a wire bandage, followed by soldering.

After removing the insulation, the bare ends of the wires are stripped, and the stranded wires are twisted at an angle of 15-300 to the wire axis. last operation performed manually (core cross section less than 0.11 mm 2), with pliers or with the help of special devices. The prepared ends of the wires are subjected to hot tinning by immersion in a solder bath.

Wire marking is necessary to facilitate installation, control, troubleshooting and repair. Use wires with colored insulation and mark them with tags, adhesive tapes or by applying markings directly to the wire insulation. Colored insulated wires are commonly used for indoor EVA installations. The wiring diagrams indicate the color of the mounting wires with abbreviated symbols or digital codes. Marking wires with adhesive tapes consists in applying bandages from this tape to the ends of the wires. Marking with the help of marking tags made of polyvinyl chloride tubes has received the greatest application. The tag is attached to the end of the wire. In this case, the tag should overlap the edge of its insulating braid by 1-3 mm. The tags are put on the wires in such a way that their slipping during shaking and vibrations is excluded.

Symbols on the surface of the marking tags are specified in wiring diagrams and are carried out in accordance with industry standards. The production of tags (marking, drying, cutting) is carried out on special machines. Mounting wires are twisted to eliminate electrical interference and reduce the mutual influence of circuits. The stranding pitch is 10-40 mm and increases depending on the increase in the wire cross-section (0.05-0.75 mm 2). This operation is performed manually with a drill or on special machines.

4 . Wire layout on the template

harness mounting wire isolated

Structural and technological development of the harness makes it possible to manufacture it outside the EVA by laying out the mounting wires and cables on the template. Depending on the configuration of the bundles, flat or three-dimensional templates are used. A flat template is a base on which, in accordance with the routing (see Fig. 2) and the configuration of the bundle, metal studs are located. Installation wires are laid between the studs. To protect the wires from damage, insulating tubes are put on the studs. To fix the ends of the wires, the design of the template provides holes located next to the studs, or special clips. The three-dimensional template has additional elements that allow you to lay out the wires and fix them in three planes.

There are universal flat templates that have holes located with a certain pitch and are designed for installing studs. The layout of the studs on the template can be changed depending on the routing and bundle configuration.

Designs of electrified templates have been developed that increase the productivity of harness manufacturing and eliminate installation errors. On such a template, the ends of the mounting wires are fixed with special clamps electrically connected to signal (green) and control (red) lamps. The lamps and clip-buttons are switched in such a way that when the template is connected to the network, two lamps of the first route light up. With the correct laying and fixing of the wire, the lights of the second route light up, etc. Electrified templates are more expensive than conventional ones, and it is advisable to use them in the mass production of EVA.

When laying out wires on templates, some general rules are defined. Several bundles should be made from wires of different cross-sections, combining wires that are close in diameter. insulation (eg 1 to 3 and 3 to 6 mm). Shielded drives must be located inside the bundle, so they start the layout with them. The screens are pre-cut and soldered, in the presence of an external metal braid, it is wrapped with a keeper tape or insulated with a tube. Short wires of small cross sections are laid inside the bundle. Long wires are laid outside to form front side. Spare wires should be on top with access to their ends. These rules are easy enough to follow when laying out manually.

The sequence of wire layout on the template is manually set in the connection table, taking into account listed rules. Often a drawing is placed on the template with the designation of the tracks. The end of the wire wound from the coil is marked with a tag and fixed on the template. The wire is cut in place after laying out between the studs and its end is marked. These transitions are repeated many times. The cutting of the ends with such a sequence of operations is carried out after knitting the bundle. Manual layout on the template is performed by the installer, and it is very laborious. In serial production, it can be mechanized using a program-controlled device.

5 . Knitting harnesses

Two (or more) insulated wires with a length of more than 50 mm running in parallel along the same route must be bundled. The only exception can be an unacceptable increase in mutual pickups in electrical circuits. For knitting, threads, cords, braid, insulating tapes, heat shrink tubes, etc. are used. The operation is usually carried out on a template. Knit step t depends on wire section, number of wires n and diameter D tourniquet. On curved sections, the pitch should be reduced depending on the diameter of the bundle bend. At the branching of the wires, the knitting should have 2-5 turns on all branches, the bandages should be made from 2-3 adjacent loops. The ends of the bundle must have bandages and end nodes.

Knitting is carried out in one, two or more threads with manual tension or with the help of devices. To reduce the complexity, the process of knitting harnesses is mechanized using pneumatic guns, and sometimes automated, by knitting harnesses on special semi-automatic machines.

To protect against mechanical damage, the tourniquet is wrapped with insulating tape along its entire length or in a certain area. If it consists of wires with cotton or silk insulation, then to protect against moisture, the bundle is impregnated with a water-repellent composition. To protect against high temperatures or aggressive environments, the bundles are placed in tubular, tape, strip or woven sheaths. removing the harness from the template.Thus, knitting harnesses is no less time-consuming operation than laying out and marking wires.

In addition to the use of various devices for the mechanization of the operations of manufacturing a tow, it is advisable to use conveyor lines in conditions of mass production. In this case, the technological process is divided into a number of small operations. At each workplace, the layout of wires of the same section and brand is completely carried out. When determining the cycle of the conveyor, they are guided by the layout operation, based on the fact that the knitting operation is easier to subordinate to the selected rhythm. For example, knitting 16-24 loops takes 3-5 minutes. Most often, the cycle of work is 5 or 7.5 minutes.

The conveyor method of making harnesses has other features. The layout of the wires is carried out continuously, winding them off the coils. A set of tags is preliminarily put on the end of the wire to mark all routes performed at a given workplace.

Apply universal templates, equipped with studs both in places of kinks and branches, and in places of subsequent cutting of wires. The layout routes are marked with the help of special stencils placed on the templates. For knitting harnesses, threads are used that can withstand sufficiently large tension forces. After knitting, the wires are cut, the bundle is removed from the stencil and the ends are cut.

The conveyor for the production of bundles is located in a horizontal plane, closed and transports templates using trolleys. In addition to templates, it is equipped with guns for knitting harnesses, devices for stripping insulation, and a tinning unit. The conveyor method simplifies the operations performed at each workplace and reduces the overall complexity of the production of harnesses. Its disadvantages are the tension of the wires during layout and the deformation of the bundle after removal from the template, which worsens the quality of knitting.

6 . Co.control

After the harness is made, the quality of the termination of the ends of wires and screens, the presence of markings, the absence of damage to current-carrying conductors and insulation, and the quality of tinning are controlled. The integrity of electrical circuits is checked by continuity probes. In circuits with a large number of intermediate connections, the resistance is measured.

During the control, the ribbon cables are checked for the absence of conductor breaks, the insulation resistance between the conductors and the ground buses, the presence of electrical connections between the connector contacts and the ribbon wire.

For control, special automated stands have been developed, for example, with the number of points to be checked is 90 and the main technological time for checking the product is not more than 30 s. Control is carried out by checking electrical circuits, comparing the states of the switches and then transferring the results to the light indication panel. Stands can work in automatic and manual modes.

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