Automated wiring harness fabricating system

Abstract: The fabrication of wiring harnesses requires many steps, such as a wire laying out step of laying out electric wires coated with insulative sheaths in a laying out array and cutting with measured length, a stripping step of the insulative sheaths at the ends of the electric wires, a crimping step of pressing terminals together with the bared ends of the electric wires in crimp contact, an inserting step of inserting into connectors the terminals pressed in crimp contact, etc. This system has an apparatus for each step modularized, and a module incorporated in the system can be increased or decreased in number depending upon a type of the desired wiring harness. For example, it is assumed now that a wiring harness fabrication line consists of an automated wire laying out module (1), a stripping module (3), two terminal-crimping modules (5), and a terminal-inserting module (7). When the type of the desired wiring harness is changed, an additional automated wire laying out module (1) and terminal-inserting module (7) are provided in this fabrication line, and eventually, there can be incorporated two of the automated wire laying out modules (1) and two of the terminal-inserting modules (7) in this fabrication line. Thus, the automated fabricating system according to the present invention is a system flexibly adjustable to the renewal of a design of the wiring harness.

Description: The present invention relates to a fabrication system for a wiring harness, and more particularly, it relates to a wiring harness fabricating system which can be flexibly adjustable to the renewal in a design of the wiring harness and multi-item mixed flow production. Wiring harness is an electric wiring system organized by a great number of wires, terminals, connectors, etc., and is incorporated in an automobile, copying machine, or the like. A fabrication process of such wiring harness includes various steps of measuring and cutting wires, laying out wires, stripping insulating sheaths at ends of wires, crimping terminals and bared wire end together for contacting, inserting a terminal to a connector receptacle, etc. Hence, it requires a great deal of labor and time to fabricate the wiring harness, and it has been highly desired to automate the fabrication process of the wiring harness. An exemplary well-known automated fabricating machine of a wiring harness is disclosed in Japanese Examined Patent Publication Nos. 46489/1985, 54245/1989, 42085/1989, 15994/1990, 66790/1991, or the international application WO 89/12900. The automated fabricating machine as described in any of the above official gazettes is an assembly for conducting a specified step or as in the case of WO 89/12900 several steps of fabricating wiring harness, which is inflexible or fixed in processing capacity at each step. Also disclosed is another prior art automated wiring harness fabricating machine in which several process steps can be conducted on an assembly line (e.g., see Japanese Unexamined Patent Publication No. 313870/1989). This type of automated wiring harness fabricating machine is an assembly unit in which several mechanisms for fabrication steps and a conveyor mechanism of a specified length for conveying a wire lay-out board are incorporated cooperatively. Wiring harness is restyled in relatively short cycles. Automobiles are, for example, changed minutely every other year and are usually restyled every four years. In such a change, main parts or bodies of the automobiles are changed, or electrical equipment for the automobiles is increased or decreased in number, or changed. With any increase, decrease or change in such electrical equipment as well as the change in the automobile main parts or bodies, the wiring harness used for the circuit wiring of such electrical equipment is naturally renewed in design. Renewal of a design of the wiring harness causes a complete change in a circuit configuration or a shape of products. Thus, the automated wiring harness fabricating machine must be that which is flexibly adjustable to the renewal of the design of the wiring harness. As mentioned above, however, the prior art automated wiring harness fabricating machine is inflexible in processing capacity at each process step and/or is an assembly unit where the conveyor mechanism of a certain length is cooperatively incorporated, and therefore, the wiring harness fabricated by the prior art apparatus is restrictive in type and feature. Accordingly, there is a disadvantage that an automated apparatus which fabricates wiring harness in a predetermined mode is useless for fabricating wiring harness of a renewed design. Such a prior art automated apparatus cannot be flexibly adjusted to the renewal of the design of wiring harnesses, and hence, it is necessary to improve the automated apparatus for fabricating such a new-design wiring harness. This brings about a problem, for example, that the operative time of the costly automated apparatus is too short to recover its manufacturing cost. The multi-item mixed flow production is preferable to other methods, allowing for the practical fabrication procedure of a wiring harness; that is, a fabrication procedure is conducted for each of the several temporary binding units, and thereafter, several of the temporary binding units are united together to produce a finished product of the wiring harness. For that purpose, various kinds of temporary binding units are first to be fabricated. In view of the enhancement of production efficiency, the various temporary binding units are preferably fabricated on parallel flows. With such a mode in which after fabricating a mass of temporary binding units of the same type, a mass of them of other type are fabricated, a finishing stage of uniting the temporary binding units of all required kinds cannot be performed till the required temporary binding units are prepared for the finishing stage. This is because such a fabrication mode is of low production efficiency. In addition to that, storage space must be prepared for keeping the produced temporary binding units. Thus, the multi-item mixed flow production is desirable. However, the prior art automated apparatus cannot fabricate the temporary binding units of different kinds on a mixed flow although it can fabricate the temporary binding units of the same kind which are all identical in the predetermined numbers of circuits and connectors. In other words, the prior art automated apparatus has a disadvantage that it is not suitable for the multi-item mixed flow production. The present invention is devised to overcome the above-mentioned disadvantages. It is an object of the present invention to provide an automated wiring harness fabricating system which is flexibly adjustable to the renewal of a design of a wiring harness. It is another object of the present invention to provide a wiring harness fabricating system which is suitable for multi-item mixed flow production in view of the actual circumstances of the fabrication of a wiring harness. In accordance with a first aspect of the present invention, there is provided an automated wiring harness fabricating apparatus comprising a number of modules arranged in series and through which wire lay-out boards are conveyed in series, wherein said number of modules comprise groups of one or more of the following modules arranged together in series: a wire laying out step module to perform a wire laying out step of laying out electric wires coated with insulating sheaths in a laying out array and cutting to a measured length, a stripping step module to perform a stripping step of stripping the insulating sheaths at the ends of the electric wires, a crimping step module to perform a crimping step of pressing terminals together with the bared ends of the electric wires in crimp contact, and an inserting step module to perform an inserting step of inserting into connectors the terminals in crimp contact with the ends of the electric wires. In accordance with a second aspect of the present invention, there is provided a method of organizing an automated wiring harness fabricating system, comprising conveying wire lay-out boards through a number of steps in series, said number of steps comprising groups of one or more of the following steps in series: a wire laying out step of laying out electric wires coated with insulating sheaths in a laying out array and cutting to a measured length, a stripping step module arranged for of stripping the insulating sheaths at ends of the electric wires, a crimping step of pressing terminals together with the bared ends of the electric wires in crimp contact, and an inserting step of inserting into connectors the terminals in crimp contact with the ends of the electric wires. In accordance with the present invention, the number of process modules for each process step can be increased or decreased depending upon capacity of a wiring harness to be fabricated. Thus, the present invention permits the wiring harness fabricating system to easily change a procedure on a fabrication line depending upon what kind of wiring harness is to be produced. Also, in accordance with the present invention, any of process steps in a fabrication line can be increased or decreased in number as required, and therefore, dispersive processing times occupied on the steps can be evened out, and therefore, the fabrication line, as a whole, can be excellent in productive efficiency. By way of example only, specific embodiments of the present invention will now be described, with reference to the accompanying drawings, in which:- Fig. 1 is a perspective view showing the whole embodiment of fabrication line of a wiring harness fabricating system according to the present invention; Fig. 2 is a diagram illustrating a structure where three modules are connected in series, presented for illustrating a common structure of the modules; Fig. 3 is a plan view showing a concrete example of a common structure of the modules; Fig. 4 is a front view showing a concrete example of a common structure of the modules; Fig. 5 is a right side view showing a concrete example of a common structure of the modules; Fig. 6 is a perspective view illustrating a concrete example of a wire lay-out board to be carried on the wiring harness fabrication line; Fig. 7 is a diagram illustrating feed holes in the wire lay-out board used in the fabricating system according to the present invention; Figs. 8 and 9 are diagrams showing modifications of feed holes in the wire lay-out board; Fig. 10 is a diagram illustrating advantages of one embodiment according to the present invention; Figs. 11A to 11D depict images of wire laying out modes of temporary binding units A to D laid out on wire lay-out boards a to d; Fig. 12 is a block diagram showing an comparative wiring harness fabrication line suitable for the multi-item mixed flow production, presented to compare with one embodiment according to the present invention; Fig. 13 is a block diagram illustrating a wiring harness fabrication line for the multi-item mixed flow production of one embodiment according to the present invention; and Fig. 14 is a block diagram illustrating a wiring harness fabrication line for the multi-item mixed flow production of another embodiment according to the present invention. Fig. 1 is a perspective view showing the whole fabrication line of an exemplary wiring harness fabricating system of the present invention. The fabrication line shown in Fig. 1 has a structure where apparatuses modularized for every process step are coupled in such an arrangement that each process step contains a specified number of the modularized apparatuses. More specifically, the fabrication line of this embodiment is comprised of three automated wire laying out modules 1a, 1b and 1c (referred to as "automated wire laying out modules 1" en bloc hereinafter), an automated taping module 2, two stripping modules 3a and 3b (referred to as "stripping modules 3" en bloc hereinafter), a stripping check module 4, four terminal crimping modules 5a, 5b, 5c and 5d (referred to as "terminal crimping modules 5" en bloc hereinafter), a crimping check module 6, three terminal inserting modules 7a, 7b and 7c (referred to as "terminal inserting modules 7" en bloc hereinafter), and a conductivity checking module 8, all of which are serially coupled in this order. When wiring harness is fabricated on this fabrication line, a predetermined wire lay-out board 9 is successively carried from module to module along a flow from the automated wire laying out modules 1 toward the conductivity checking module 8 so as to build up wiring harness on the wire lay-out board 9. The automated wire laying out modules 1 are apparatuses for automatically laying out electric wires on the wire layout board 9 and cutting electric wires to a measured length. Specified kinds of electric wire group 10 involved in the laying out are stored in the vicinity of the automated wire laying out modules 1. Electric wires of the electric wire group 10 are selectively taken in the automated wire laying out modules 1, laid out on the wire lay-out board 9, and then cut to a measured length. In this embodiment, there are three of the automated wire laying out modules 1a, 1b and 1c disposed in series. Given now that each individual one of the automated wire laying out modules 1 is capable of laying out with thirty kinds of electric wires different in color, thickness and the like, an arrangement which has three of the automated wire laying out modules 1 disposed in series can treat ninety kinds of electric wires to be laid out. Thus, this arrangement is adjustable to any variation in the laying out by increasing or decreasing the number of the automated wire laying out modules 1 depending upon which kinds of electric wires are to be laid out on the wire lay-out board 9. The wire lay-out board 9, after wires are laid out by the automated wire laying out modules 1, is carried to the automated taping module 2 positioned downstreamwise in the fabrication flow, and a bundle of the electric wires laid out on the wire lay-out board 9 is taped up in predetermined positions so as not to be untidy. Although only one automated taping module is provided in this embodiment, the automated taping module 2 may be increased in number so that many of them are connected in series if a taping capability in this fabrication line must be reinforced. Then, the wire lay-out board 9 is carried to the stripping modules 3a and 3b connected in series to each other downstreamwise from the automated taping module 2. In the stripping modules 3, an insulative sheath at the end of each wire used for laying out on the wire lay-out board 9 is stripped. In this embodiment, there are two stripping modules 3 connected to each other so as to reinforce a stripping capability of this fabrication line. If required, the number of the stripping modules 3 may be increased. If no such stripping capability is required, only one stripping module may be used. After the step of stripping, the wire lay-out board 9 is carried to the stripping check module 4 connected downstreamwise from the stripping modules 3. The stripping check module 4 has, for example, a check camera to check if the end of the electric wire is stripped well, if the bared end of the electric wire is bent or untidy, and so forth. When it is checked that the end of the electric wire is incorrectly stripped, the wire lay-out board 9 containing the incorrectly stripped end of the electric wire may be automatically removed from the fabrication line, or otherwise, a lamp may be utilized to inform that the incorrected stripped end of the electric wire is detected. There are four of the terminal crimping modules 5a, 5b, 5c and 5d connected in series downstreamwise from the stripping check module 4. In this embodiment, since the fabrication line makes a turn at a point downstreamwise from the second terminal crimping module 5b, a conveyor-buffer module 11 is interposed between the second terminal crimping module 5b and the third terminal crimping module 5c. In the conveyor-buffer module 11, the wire lay-out board 9 carried from the second terminal crimping module 5b turns along a conveyor line and is further carried to the third terminal crimping module 5c. Also, in the conveyor-buffer module 11, the wire lay-out board 9 is halted in the course of the conveyance for a predetermined period to regulate a timing of carrying the wire lay-out board 9 toward the third terminal crimping module 5c. In each of the four terminal crimping modules 5, the bared end of the electric wire having its core wire uncovered with sheath and a terminal are pressed together in crimp contact with each other. The electric wires laid out on the wire lay-out board 9 include varieties depending upon a circuit necessary for a wiring harness, and they vary in thickness from filament to cable. When an electric wire different in thickness is used, a terminal pressed together in crimp contact with the electric wire must be accordingly changed, and a crimper and a die for the terminal crimping must be changed in its width and pitch in accordance with the thickness of the electric wire. In this embodiment, there is provided an arrangement consisting of the four terminal crimping modules 5a, 5b, 5c and 5d so that, for example, eight kinds of electric wires different in thickness can be crimped to their respective optimum terminals. Each of the terminal crimping modules 5a, 5b, 5c and 5d has two terminal crimping heads, and two electric wires different in thickness from each other can be crimped to different terminals. Thus, if there are four of the terminal crimping modules 5, there lie eight variations in terminal crimping to eight kinds of electric wires different in thickness. The number of the terminal crimping modules 5 arranged at a time may be increased or decreased depending upon the number of kinds of electric wires. The crimping check module 6 is coupled downstreamwise from the terminal crimping modules 5. The crimping check module 6 has, for example, a check camera to check if the end of the electric wire and the terminal are pressed together in good crimp contact with each other. It is also checked if the end of the electric wire crimped to the terminal is abnormally bent. If a bad crimp contact of the electric wire with the terminal is detected by a check in the crimping check module 6, the wire lay-out board 9 which contains the electric wire suffering from the bad crimp contact may be automatically removed from the fabrication line as in the above case of the stripping check module 4, or otherwise, a warning lamp may be utilized, for example, to inform that the bad crimp contact with the terminal has been detected. The three terminal inserting modules 7 are connected in series to one another downstreamwise from the crimping check module 6. The terminal inserting modules 7 are apparatuses for automatically inserting into a connector receptacle the terminal crimped to the end of the electric wire. There are three of the terminal inserting modules 7 so as to be adjustable to kinds of the terminal inserted into the connector receptacles. The first terminal inserting module 7a inserts the terminal of a-type into the connector receptacle, the second terminal inserting module 7b inserts the terminal of b-type into the connector receptacle, and the third terminal inserting module 7c inserts the terminal of c-type into the connector receptacle, for example. The terminal inserting modules 7 may be increased in number when increased numbers of different kinds of terminals are to be used; or they may be decreased when decreased numbers of different kinds of terminals are to be used. The conductivity checking module 8 is coupled downstreamwise from the terminal inserting module 7. In the conductivity checking module 8, a checking coupler is connected to the connector receptacle where the terminal is inserted to conduct a conductivity check to the electric wire used for the laying out. When a wire lay-out board 9 containing an electric wire of poor conductivity is found by the conductivity check, the wire lay-out board 9 may be automatically removed from the fabrication line. An extra arrangement may be provided to indicate that the poor conductivity has been detected. A buffer module 12 is coupled downstreamwise from the conductivity checking module 8, and the wire lay-out board 9 carried to the buffer module 12 is transferred to the next fabrication stage because the required processing in this portion 23 can intrude into the next module upstreamwise in the fabrication line in this embodiment. In this way, the wire lay-out board can be conveyed without trouble in case where the wire lay-out board is to be carried from the module 20A downstreamwise to the module 20B. There is another advantage that an additional conveyor apparatus does not have to be provided between the module 20A and the module 20B. The projecting portion 23 may intrude not into the upstreamwise module but instead into the downstreamwise module. Another feature of the above-mentioned common arrangement is that the conveyor apparatuses are not aligned along the modules coupled to one another; that is, the conveyor apparatuses 22A, 22B and 22C are positioned on alternately the left half and the right half of the base frames about the center line of the widthwise extension of the base frames; for example, the conveyor apparatus 22A is on the left half of the widthwise extension of the base frame 21A, the conveyor apparatus 22B is on the right half of the widthwise extension of the base frame 21B, and the conveyor apparatus 22C is on the left half of the widthwise extension of the base frame 21C. With such an arrangement, the projecting portion 23 intruding into the upstreamwise module 20 would never bump against the conveyor apparatus 22 provided in the module 20, and moreover, since the projecting portion 23 of the length L0 partially overlaps with the conveyor apparatus 22 of the upstreamwise fabrication line is completed. Common structural features of the modules will now be described. Any of the modules (including the step of checking) each of which conducts processing for each process step can be increased in number as required at any time. The order of the coupling of the modules can be changed in any sequence as the wiring harness fabricating process requires. The requirements for the modules to be flexibly coupled to others are that all the modules have common structural features which allow them to be freely coupled to each other. In this embodiment, the modules are provided with a common conveyor mechanism to implement the modules which can be freely coupled to each other as mentioned above. Fig. 2 is a diagram illustrating an arrangement where three modules 20A, 20B and 20C are connected in series. The modules 20A, 20B and 20C include common arrangements like base frames 21A, 21B and 21C and conveyor apparatuses 22A, 22B and 22C (hereinafter the alphabetical symbols A, B and C suffixed to the numerals 20, 21, 22 are omitted when the modules, base frames and conveyor apparatuses are referred to en bloc). One of features of the common arrangement is that the conveyor apparatus 22 provided in the base frame 21 has a projecting portion 23 extending outward from an edge of the base frame 21 with a predetermined length L0. The projecting module 20 in parallel, the wire lay-out board can be transferred, for example, from the conveyor apparatus 22A in the upstreamwise module like the module 20A to the conveyor apparatus 22B in the downstreamwise module 20B. Lengths L1, L2 and L3 of the base frames 21 in the respective modules 20 may vary from module to module or may be equal to one another. Widths of the base frames 21 in the respective modules may also vary from module to module or may be equal to each other. A common arrangement of the modules 20 will be described below in conjunction with a sample structure. Fig. 3 is a plan view showing a concrete example of a common arrangement of the modules, Fig. 4 is a front view of the same, and Fig. 5 is a right side view of the same. Referring to Figs. 3 to 5, the module 20 includes a lower base frame 21a having a shape of a rectangular parallelopiped and an upper base frame 21b mounted on the lower base frame 21a, and four casters 24 with stoppers are attached to the bottom of the lower base frame 21a. Thus, both the lower base frame 21a and the upper base frame 21b can be easily moved to a desired position and kept immovable in position. The conveyor apparatus 22 has an elongated mounting member 25 fixed on the lower base frame 21a. The mounting member 25 is provided with a first pulley 26 on its right terminal and a second pulley 27 on its left terminal, and a conveyor timing belt 28 stretches between the first pulley 26 and the second pulley 27. The first pulley 26 is interlocked with a timing pulley 33 attached through a bearing mechanism 32. A servo motor 34 for driving the conveyor apparatus 22 is mounted in the lower base frame 21a. A drive pulley 36 is attached to a rotation shaft 35 of the servo motor 34, and a timing belt 37 extends between the drive pulley 36 and the timing pulley 33. Thus, the rotation force of the servo motor 34 is transmitted through the timing drive pulley 36 and the timing belt 37 to the timing pulley 33, the rotation of the timing pulley 33 is transmitted through the bearing mechanism 32 to the first pulley 26, and the rotation of the first pulley 26 permits the conveyor timing belt 28 to move. A movable member 30 is attached to the conveyor timing belt 28 through a connecting member 29. A guide rail 31, which is held above the mounting member 25 and extends in parallel with the conveyor belt 28, guides the movable member 30 so that the movable member 30 can be freely moved in the lateral directions in Figs. 3 and 4. Thus, as the conveyor timing belt 28 is moved, the movable member 30 connected to the conveyor timing belt 28 via the connecting member 29 is moved in the lateral directions according to the movement of the conveyor timing belt 28. The movable member 30 has an extension of a specified length in its movable directions, and two pin units 38a and 38b are fixed thereto at a specified interval along the movable directions. The pin units 38a and 38b have positioning pins 39a and 39b, respectively, which are vertically moved by a hydraulic cylinder. A distance between the positioning pins 39a and 39b is preset, for example, 505 mm. The positioning pins 39a and 39b are raised so as to engage with feed holes formed in the wire lay-out board as mentioned later. As stated above, using two positioning pins 39 and settling those pins 39 at a specified interval bring about an advantage that the wire lay-out board can be accurately positioned and never be unsteady when it is conveyed. With a single positioning pin alone, the wire lay-out board might be shaky in the conveying direction and orthogonal direction thereto while it is being conveyed, but providing the two positioning pins 39a and 39b at the specified interval therebetween as in this embodiment allows the wire lay-out board to be accurately positioned by the positioning pins 39a and 39b and to be conveyed without shaking. In a variation of this embodiment, there may be three or more of the positioning pins 39, so that the wire lay-out board can be positioned by so many pins and conveyed. A single positioning pin 39 might be enough if the conveyor apparatus is provided with a conveyor guide which prevents the wire lay-out board from shaking in the orthogonal direction to the conveying direction during the conveyance. A feature of the module 20 is that a left end (in Figs. 3 and 4) of the conveyor apparatus 22 acts as the projecting portion 23 which projects to the left from edges of the base frames 21a and 21b. The extension of the projecting portion 23 from the edges is determined to L0 (e.g., L0 is sized by adding a predetermined margin α to the interval 505 mm between the two positioning pins 39a and 39b; that is, L0 = 505 mm + α), the right positioning pin 39b of the two positioning pins 39a and 39b fixed to the movable member 30 can run out of the guide frames 21a and 21b under the condition that the movable member 30 is in its most leftward position. When an additional module is coupled to the module 20 on its left side, the projecting portion 23 intrudes into the base frame of the module, and the two positioning pins 39a and 39b in the projecting portion 23 receive the wire lay-out board carried into the additional module to take it in the module 20. The module 20 further includes a proximity sensor 41 provided in the upper base frame 21b for temporarily detecting the wire lay-out board, and a cylinder 42 provided in the vicinity of the proximity sensor 41 for temporarily halting the wire lay-out board. In Figs. 3 and 4, as the wire lay-out board is carried from the left, a leading end of the wire layout board is detected by the proximity sensor 41. An output of the detection result from the proximity sensor 41 is applied to a cylinder control apparatus (not shown), and the cylinder 42 is lifted in response to the output from the proximity sensor 41. Then, the leading end of the wire layout board bumps against the lifted cylinder 42 and halts. The feed holes are formed in a reverse side of the wire lay-out board in positions opposed to the positioning pins 39a and 39b, and therefore, the positioning pins 39a and 39b are, when raised, inserted into the feed holes in the wire lay-out board. After that, the cylinder 42 is lowered. In the upper left of Fig. 4, two-dot-dash line represents the wire lay-out board 9 lying in its initial halt position. In the upper right of Fig. 4, two-dot-dash line expresses the wire lay-out board 9 lying in its most rightward position through the conveyance. In such a condition, since the projecting portion 23B of the conveyor apparatus in the next module coupled to the module 20 on its right side intrudes into the module 20 as expressed by two-dot-dash line in Fig. 3, the wire lay-out board 9 is received on the conveyor apparatus (on its projecting portion 23B) in the next module and transferred to the further next module. In Figs. 3 and 5, reference numeral 43 denotes a roller retaining opposite ends of the wire lay-out board during the conveyance of the wire lay-out board. Also in Figs. 3 and 5, reference numeral 44 denotes a processing mechanism mounting plate. In assembling the module 20 so as to act as a stripping module, a stripping mechanism is mounted on the processing mechanism mounting plate 44. The mounting plate 44 is located in an exemplary position in Fig. 3, and it may be replaced with a larger one depending upon the kind of processing mechanism to be installed thereon or may be placed in another position. Fig. 6 is a perspective view showing a concrete example of a wire lay-out board conveyed along the wiring harness fabrication line. In the wiring harness fabrication line, a wiring harness is gradually built up on the wire lay-out board 9 while the wire lay-out board as shown in Fig. 6 is being conveyed sequentially from one process step to another. Referring to Fig. 6, a configuration of the wire lay-out board 9 will be simply described. The wire lay-out board 9 includes a base plate 52 and a pin board 53 detachably fixed to the base plate 52. The base plate 52 can be used by processes for fabricating any type of wiring harness though the pin board 53 must be replaced with one suitable for a particular type of wiring harness. A number of lay-out pins 54, which are for catching electric wires therearound, are planted on the pin board 53. The base plate 52 has many wire clamps 55 aligned along its elongated front side, and a parallel comb 56 is placed inside the wire clamps 55. Electric wires W have their one ends pinched by the wire clamps 55 and pass through the parallel comb 56 and are hitched round specified ones of the layout pins 54 on the pin board 53 so as to accomplish the laying out. The other ends of the electric wires pass through the parallel comb 56 and are pinched by the wire clamps 55. Thus, the ends of the electric wires W laid out on the wire lay-out board 9 run out of the wire clamps 55 toward the front (the upper left in Fig. 6) by a specified length. The ends of the electric wires W running out of the wire clamps 55 are kept lined-up by the wire clamps. Thus, the stripping step of stripping insulative sheaths at the ends of the electric wires W, the crimping step of pressing the bared ends of the electric wires W and terminals together in crimp contact with each other, and other steps are conducted by conveying the wire lay-out board 9 in the direction of arrow 62 at constant intermittent pitches. The base plate 52 further includes a receptacle mounting plate 58 slidably attached thereto by a slide guide bar 57. The receptacle mounting plate 58 can slide in the direction of arrow 59 or the longitudinal direction of the base plate 52. In the lay-out step of the electric wires W on the wire layout board 53, the stripping step of stripping insulative sheaths at the ends of the electric wires W, the crimping step of the pressing the bared ends of the electric wires W and terminals together in crimp contact with each other, and the like, the receptacle mounting plate 58 is set in position, retracted behind the pin board 53 as shown in Fig. 6. On the other hand, in the terminal inserting step of inserting a terminal into a connector receptacle, the receptacle mounting plate 58 is slid toward the frontmost position so that the terminal can be easily inserted into a connector receptacle 60 mounted on the receptacle mounting plate 58. As has been described, the wire lay-out board 9 as shown in Fig. 6 has a configuration suitable for fabricating wiring harness by a machine in a mechanized wiring harness fabrication line. Fig. 7 is a diagram illustrating the feed holes formed in the bottom side of the wire lay-out board 9. As shown in Fig. 7, at least two pairs 45 and 46 of feed holes are formed in the bottom side of the base plate 52 (see Fig. 6). One of the pairs of feed holes, 45, is formed, for example, on the left side of the widthwise extension of the wire lay-out board 9 orthogonal to the conveying direction while the other pair 46 of feed holes are formed on its right side. Both of the pairs 45 and 46 of feed holes have two holes 45a and 45b (or 46a and 46b), and the interval between the holes 45a and 45b (or 46a and 46b) is set to a predetermined size; in this embodiment, for example, 505 mm equivalent to the interval between the positioning pins 39a and 39b. In one of the pairs 45 of feed holes of the two pairs 45 and 46, the positioning pins are inserted in the module at the previous stage for the conveyance. In the other pair 46 of feed holes, the positioning pins are inserted in the module at the subsequent stage for the conveyance. Figs. 8 and 9 are diagrams showing variations of the feed holes formed in the wire lay-out board 9. The feed hole pairs 45 and 46 may be formed symmetrically about the center of the wire lay-out board 9, as shown in Fig. 8. Also, as shown in Fig. 9, there are formed six feed holes 45a, 45b, 45c, 46a, 46b and 46c, for example; and two pairs A1 and A2 consisting of the feed holes 45a and 45b, and 46a and 46b, respectively, or two pairs B1 and B2 consisting of the feed holes 45b and 45c, and 46b and 46c, respectively, may be used to convey the wire lay-out board 9. In the above-mentioned embodiment, the automated fabricating apparatuses for conducting the process steps are modularized for each step. Therefore, the number of modules in each of the steps of the fabrication line can be regulated in accordance with a particular type of a required wiring harness. If the type of the required wiring harness is changed because of the renewal of a design of the wiring harness or the like, the number of the modules of the fabrication line or the order of its arrangement may be changed in accordance with the change in the required wiring harness, and thus, the fabrication line which is flexibly adjustable to the renewal of a design of a wiring harness can be easily assembled. The advantage of this embodiment will be described more specifically below with reference to the accompanying drawings. It is now assumed that the fabrication line of a wiring harness has a system architecture as illustrated in Fig. 10A; that is, the fabrication line includes an automated wire laying out module 1, a stripping module 3, two crimping modules 5a and 5b, and a terminal inserting module 7, and the situation' is that a design of a wiring harness is changed, and therefore the number of circuits of the required wiring harness is to be increased. In this case, to cope with the renewal of the design of a wiring harness, as shown in Fig. 10B, an automated wire laying out module 1b is added so that two automated wire laying out modules 1a and 1b can be incorporated in the fabrication line, and a terminal inserting module 7b is added so that the terminal inserting modules 7a and 7b can be provided in the fabrication line; and accordingly, the required wiring harness increased in circuit number due to the renewal of its design can be fabricated. A simple change in the procedure allows the apparatus modularized in each process step to be increased or decreased in number, and hence, the automated fabricating machine can be flexibly adjustable to the renewal of the design of a wiring harness without idling its own features. As has been described, according to the present invention, an automated wiring harness fabricating system can be provided which can be flexibly adjustable to any change in a type or design of a required wiring harness. The present invention can also be applied to a wiring harness fabrication line suitable for multi-item mixed flow production, as explained later. Then, the automated wiring harness fabricating line suitable for the multi-item fixed flow production where the modularized apparatuses for each process steps are coupled to each other will be specifically explained. A wiring harness is usually comprised of a plurality of temporary binding units. For a wiring harness of model number X, for example, it may be comprised of four temporary binding units A, B, C and D. The temporary binding units A, B, C and D are different in length of wires, types of the wires, and the number of the wires from one another, and if electric wires different in thickness and type are used, conditions of stripping insulating sheaths at the ends of electric wires, types of terminals crimped to the bared ends of the electric wires, and terminal crimping conditions accordingly vary. When the wiring harness of model number X is to be fabricated, wire lay-out boards a, b, c and d prepared for the temporary binding units A, B, C and D, respectively, are employed for the procedure of multi-item mixed flow productions of the temporary binding units A, B , C and D in the wiring harness fabrication line. Figs. 11A to 11D depict images of laying out modes of the temporary binding units A, B, C and D arranged on the wire lay-out boards a, b, c and d, respectively. In Figs. 11A to 11D, not all the electric wires used for actual temporary binding units are shown, and the laying out modes are not practical but illustrative. The four temporary binding units A, B, C and D as shown in Figs. 11A to 11D are formed of eight, nineteen, seventeen and twenty-five electric wires, respectively. A case where the four temporary binding units A, B, C and D are fabricated in a wiring harness fabricating line as shown in Fig. 12 will be discussed. Fig. 12 is a block diagram showing a comparative wiring harness fabrication line, presented for a comparison with the wiring harness fabrication line for the multi-item mixed flow production of the preferred embodiment according to the present invention. The wiring harness fabrication line for the comparison has eight process steps: Steps 1 and 2 for automated wire laying out modules for automatically laying out electric wires on a wire lay-out board and cutting with measured length, Step 3 for a stripping module of stripping a sheath at an end of an electric wire; Steps 4, 5 and 6 for terminal crimping modules of pressing a bared electric wire and a terminal together in crimp contact with each other, Step 7 for a terminal inserting module of inserting terminal into a receptacle, and Step 8 for a removing module for removing temporary binding units of a wiring harness from a wire lay-out board. These eight steps are sequentially linked into a flow. In the wiring harness fabrication line as shown in Fig. 12, the time occupied on each of the process steps 1 to 8 in the event of fabricating the four temporary binding units A, B, C and D is shown in Table 1. Although the temporary binding unit A is formed of eight electric wires, for example, four of the eight electric wires are laid out by the automated wire laying out module 1 at Step 1, and the remaining four electric wires are laid out by the automated wire laying out module 2 at Step 2. Then, it takes 38 seconds to complete the laying out of the four electric wires at Step 1, and 38 seconds to complete the laying out of the remaining four electric wires at Step 2. At Step 3, foremost ends of the eight electric wires used for the laying out are stripped (there are sixteen ends in the eight electric wires). Assuming that it takes 3 seconds to strip one end of an electric wire, it should take 48 seconds to strip the sixteen ends of the eight electric wires. Then, at Steps 4, 5 and 6, terminals are pressed together with the bared ends of the electric wires in crimp contact with each other by the terminal crimping module. There are sixteen of the bared ends of the electric wires which are to be in crimp-style contact with the terminals, and each of the terminals must be that which is of predetermined style for corresponding one of the ends of the electric wires. Thus, in this embodiment, terminals are crimped to eight of the ends of the electric wires at Step 4, Step 5 is skipped, and terminals are crimped to the remaining eight ends of the electric wires at Step 6. Assuming now that it takes 3.6 seconds to make a crimp contact of one terminal, it takes 29 seconds (8 x 3.6 = 29 sec.) at Step 4, 0 second (0 x 3.6 = 0 sec.) at Step 5, and 29 seconds (8 x 3.6 = 29) at Step 6. At Step 7 the terminals are inserted into connector receptacles by the terminal inserting module. There are sixteen terminals (8 x 2 = 16) because the eight electric wires have their respective opposite ends crimped to the terminals. There are, however, eight terminals so-called "disunited terminals" out of sixteen terminals. These disunited terminals are not inserted into the connector receptacles when the wiring harness is in its temporary binding state, but inserted into connector receptacles when the temporary binding units are united together. It is assumed now that there are eight of the terminals which are to be inserted in the connector receptacles in uniting. If it takes 3.3 seconds to insert one terminal, the total time occupied at Step 7 is 27 seconds. Finally, it takes 40 seconds to take the temporary binding unit A out of the wire lay-out board at Step 8. It also takes 6 seconds to convey the wire lay-out board between the adjacent process steps. Then, in order to fabricate the temporary binding unit A alone by using the wiring harness fabrication line shown in Fig. 12, the wire lay-out board may be transferred from step to step in a cycle time of 48 + 6 = 54 seconds where 6 seconds are occupied on the conveyance between the adjacent steps is added to 48 seconds at Step 3 on which the longest processing time is occupied. Table 1 also presents all data about the number of electric wires and the number of ends of the electric wires which are processed at each step, and the time occupied on completing the step. In a practical fabrication of a wiring harness, for example, in fabricating the wiring harness of model number X, no such procedure that a required number of the temporary binding units A are first fabricated, a required number of the temporary binding units B are then fabricated, a required number of the temporary binding units C are fabricated, and at last a required number of the temporary binding units D are fabricated is employed. The reason is that if various temporary binding units are fabricated one type after another as required in number, a warehouse or the like is needed, as mentioned in the prior art description, to store products of the temporary binding unit A till finished products of the wiring harness of model number X are obtained, and the fabrication cannot be reasonably effected. When wiring harnesses of model number X are fabricated by using the wiring harness fabrication line as shown in Fig. 12, the temporary binding units A, B, C and D are fabricated on the basis of mixed flow production; initially the wire layout board "a" for fabricating the temporary binding unit A is set at Step 8, the wire lay-out board "b" for fabricating the temporary binding unit B is set at Step 7, the wire lay-out board "c" for fabricating the temporary binding unit C is set at Step 6, the wire lay-out board "d" for fabricating the temporary binding unit D is set at Step 5, and similarly the wire lay-out board "a" at Step 4, the wire lay-out board "b" at Step 3, the wire lay-out board "c" at Step 2, and the wire lay-out board "d" at Step 1 are respectively set. Thus, the temporary binding units A, B, C and D are fabricated on the bases of mixed flow production. Table 2 shows a time occupied on each of the process steps in the event of fabricating the four temporary binding units A, B, C and D on the basis of mixed flow production. Referring to Table 2, at Stage S1, the temporary binding unit D is fabricated at Step 1, the temporary binding unit C is fabricated at Step 2, the temporary binding unit B is fabricated at Step 3, and the temporary binding unit A is fabricated at Step 4, and similarly the temporary binding units D, C, B, and A are fabricated at Steps 5, 6, 7 and 8. In this case, Step 1 requires the longest processing time of 124 seconds. At Stage S2, the temporary binding units A, D, C, B, A, D, C and B are fabricated at Steps 1, 2, 3, 4, 5, 6, 7 and 8, respectively. Step 2 requires the longest processing time of 114 seconds at Stage S2. At Stage S3, the temporary binding units B, A, D, C, B, A, D and C are fabricated at Steps 1, 2, 3, 4, 5, 6, 7 and 8, respectively, and Step 7 requires the longest processing time of 165 seconds. At Stage S4, the temporary binding units C, B, A, D, C, B, A and D are fabricated at Steps 1, 2, 3, 4, 5, 6, 7 and 8, and Step 4 requires the longest processing time of 98 seconds. The above Stages S1 to S4 are successively repeated to fabricate the temporary binding units A, B, C and D on the basis of mixed flow production. In conducting such a mixed flow production, a conveyance cycle time at which the wire lay-out board is to be transferred from step to step must be adjusted to the step occupying the longest processing time at each of Stages S1 to S4. Therefore, Stages S1 to S4 require the following operation times, respectively: Stage S1: 124 sec. at Step 1 + 6 sec. of conveyance time between the adjacent steps = 130 sec. Stage S2: 114 sec. at Step 2 + 6 sec. of conveyance time between the adjacent steps = 120 sec. Stage S3: 165 sec. at Step 7 + 6 sec. of conveyance time between the adjacent steps = 171 sec. Stage S4: 98 sec. at Step 4 + 6 sec. of conveyance time between the adjacent steps = 104 sec. Thus, the temporary binding units A, B, C and D each of which is singular in number, or a set of the temporary binding units of model number X, are fabricated in a cycle time of 130 + 120 + 171 + 104 = 525 sec. Given now that the wiring harness fabrication line works for twenty hours a day, the production per day is expressed as follows: 20 x 3600 sec. x 0.8 (operation rate) ÷ 525 sec. = 109 sets the production per month under the condition of 20-day operation is expressed as follows: 109 sets x 20 days = 2180 sets The productive efficiency of the wiring harness fabrication line presented for the comparison in Fig. 12 can be explained as in the above. There will now be described below a case where the wiring harnesses of model number X consisting of the temporary binding units A, B, C and D as mentioned above are to be fabricated in a wiring harness fabrication line for the multi-item mixed flow production of a preferred embodiment according to the present invention. Fig. 13 is a block diagram illustrating the wiring harness fabrication line for the multi-item mixed flow production of the preferred embodiment according to the present invention. A feature of the wiring harness fabrication line shown in Fig. 13 is that buffers are incorporated in Steps 3, 5, 9 and 11. The remaining Steps 1, 2, 4, 6, 7, 8, 10 and 12 are organized completely the same with Steps 1, 2, 3, 4, 5, 6, 7 and 8 previously stated with reference to Fig. 12. For example, at Steps 1 and 2, electric wires are laid out by automated wire laying out modules. Step 3 is a buffer where a wire lay-out board already processed at Step 2 is temporarily stored on standby. At Step 4, insulative sheaths at the ends of the electric wires laid out on the lay-out board are stripped by a stripping module. Step 5 is a buffer where the wire lay-out board processed at Step 4 is temporarily stored on standby. At Steps 6, 7 and 8, terminal crimping modules are provided to press terminals together with the bared ends of the electric wires in crimp contact with each other. Step 9 is a buffer where the wire lay-out board subjected to a terminal crimping operation at Step 8 is temporarily stored on standby. At Step 10, the terminals are inserted into connector receptacles by a terminal inserting modules. Step 11 is a buffer where the wire lay-out board is temporarily stored on standby. Finally, at Step 12, the finished temporary binding unit is removed from the wire lay-out board. In this embodiment, one of the important features is that the buffers are incorporated where a processing subject is changed between any adjacent steps in a fabrication line consisting of a plurality of process steps. The buffers are utilized to temporarily store on standby the wire lay-out board already processed at the previous step and immediately feed the wire lay-out board to the subsequent step when an operation at the subsequent step is ready. Thus, when the wire lay-out board already processed at any previous step is conveyed to the succeeding step, the wire lay-out board is temporarily stored on standby in a buffer module if an operation at the succeeding step is not ready because it is going on to the preceding wire lay-out board. In this way, the preceding step can commence its operation to the succeeding wire lay-out board without delay. Once an operation at the succeeding step is ready, the wire lay-out board is immediately supplied from the buffer module to the succeeding step. Thus, even if the processing subject and time at a step vary among the wire lay-out boards, such differences can be absorbed by the buffer, and consequently, the total processing time occupied on going for a round in the whole fabrication line can be saved. A processing time in the wiring harness fabrication line shown in Fig. 13 will be described in detail. Table 3 presents a time occupied on each process step in the event of fabricating the temporary binding units A, B, C and D of the wiring harness of model number X as in the above-mentioned case in the wiring harness fabricating line shown in Fig. 13. As mentioned above, a buffer is interposed between adjacent steps of different operation subjects. Thus, there is no need to consider differences in processing time among the steps, regarding a cycle in which the wire lay-out board is conveyed between the steps. This means that the conveyance cycle may be adjusted to the processing time at a step occupying the longest total time in the steps for the same process in fabricating the temporary binding units A, B, C and D. As shown in Table 3, Step 10 requires the longest total processing time in its terminal inserting process; 27 sec. is occupied on the terminal insertion as to the temporary binding unit A, 119 sec. for the terminal insertion as to the temporary binding unit B, 113 sec. for the terminal insertion as to the temporary binding unit C, and 165 sec. for the terminal insertion as to the temporary binding unit D. Thus, the conveyance cycle in this fabrication line can be set as expressed below: 27 + 119 + 113 + 165 + (6 + 6 + 6 + 6) = 448 sec. Four 6s in the above equation represent the conveyance time between any adjacent steps as to the temporary binding units A, B, C and D. The productive efficiency of the wiring harness fabrication line can be expressed as follows: Assuming that the fabrication line works for twenty hours a day, the production per day is expressed as follows: 20 x 3600 sec. x 0.8 (operation rate) ÷ 448 sec. = 128 sets the production per month under the condition of 20-day operation is obtained as follows: 128 sets x 20 days = 2560 sets Therefore, this wiring harness fabrication line can enhance the production as can be seen in the following equations, compared with the wiring harness fabrication line as previously mentioned with reference to Fig. 12: As to the production per day: 128 - 109 = 19 sets As to the production per month: 2560 - 2180 = 380 sets As has been described, a buffer is interposed between any adjacent steps of the different processing subjects, so that the wire lay-out board, when transferred from one step to another, can be temporarily stored on standby in the buffer even if a time occupied on processing an item of the wire layout board is short and the time occupied on processing another item of the subsequent wire lay-out board is long. Thus, the conveyance cycle of the wire lay-out board can be determined based upon a processing time occupied by a step of the longest processing time in the fabrication line, regardless of a difference in the processing time varying from item to item between the process steps. In this way, the wiring harness fabricating line can be operated with the greatest efficiency. Changing the number of each of the process steps of the wiring harness fabrication line may be an alternative of the above-mentioned arrangement where the buffers are incorporated in the wiring harness fabrication line, and thereby the productive efficiency of the wiring harness fabrication line can be enhanced. Fig. 14 is a block diagram illustrating a wiring harness fabricating line where its processing modules are selectively added, or the number of a specified process step is increased, so as to enhance the productive efficiency. The wiring harness fabrication line as shown in Fig. 14 is improved, compared with the wiring harness fabrication line as shown in Fig. 12, in that additional wire laying out step, stripping step, crimping step and inserting step are incorporated, one to each individual step. Incorporating additional steps in this way, dispersive processing times at the steps in the mixed flow production of various temporary binding units can be evened out. A case of fabricating the four temporary binding units A, B, C and D of the wiring harness of model number X will now be discussed. As stated before, the temporary binding unit A, B, C and D consist of eight, nineteen, seventeen and twenty-five electric wires, respectively. In case where the wiring harness fabrication line is utilized to fabricate the four temporary binding units A, B, C and D, times occupied on conducting Steps 1 to 12 are presented in Table 4. The temporary binding unit A consists of eight electric wires, and three of the eight wires are laid out at Step 1, three of the remaining ones are laid out at Step 2, and the still remaining two are laid out at Step 3, respectively, in the automated wire laying out module. Completing each of Step 1 and Step 2 occupies 29 seconds, and completing Step 3 occupies 19 seconds. At steps 4 and 5, sheaths at the ends of the electric wires already laid out on the wire lay-out board are stripped by the stripping module. Since there are sixteen (8 x 2 = 16) of the ends of the electric wires laid out on the wire lay-out board, and therefore, eight of the ends are stripped at Step 4, and the remaining eight of the ends are stripped at Step 5. It takes 3 seconds to strip one end, and therefore, each of Step 4 and Step 5 occupies 24 seconds. Subsequently, at Steps 6, 7, 8 and 9, terminals are pressed together with the bared ends of the electric wires in crimp contact. There are sixteen of the ends of the electric wires which are to be crimped to the terminals, and each end must be crimped to a corresponding terminal of predetermined mode. In this embodiment, the terminal crimping modules at Steps 7 and 9 in all the modules at Steps 6 to 9 are used to make a crimp contact with terminals. Since it takes 3.6 seconds to make a crimp contact with one terminal, Step 7 occupies 29 seconds (8 x 3.6 = 29) if eight of the ends are to be pressed in crimp contact with the terminals, and Step 9 also occupies 29 seconds (8 x 3.6 = 29) if the remaining eight of the ends are to be pressed in crimp contact with the terminals. In the course of fabricating the temporary binding unit A, crimping is not conducted at Step 6 and Step 8, and therefore, each these steps occupies 0 second. After that, the terminals are inserted into connector receptacles by the terminal inserting modules at Steps 10 and 11. The terminals are pressed in crimp contact with the opposite ends of the eight electric wires, and sixteen (8 x 2 = 16) terminals are to be inserted in the connector receptacles. Eight of them are the so-called disunited terminals which should not be inserted into the connector receptacles when they are temporarily bound. Thus, the remaining eight terminals are inserted into the connector receptacles. It takes 3.3 seconds to insert one terminal, and each of Step 10 and Step 11 occupies 4 x 3.3 = 13 sec. Eventually, the temporary binding unit A is removed from the wire lay-out board at Step 12. It takes 40 seconds. Similarly, in fabricating the temporary binding unit B, seven of the electric wires are laid out on a wire lay-out board at Step 1 in 67 seconds, six of the electric wires are laid out on the wire lay-out board at Step 2 in 57 seconds, and the remaining six electric wires are laid out on the wire lay-out board at Step 3 in 57 seconds. Stripping at Step 4 occupies 57 seconds, and stripping at Step 5 also occupies 57 seconds. Terminal-crimping at Step 6 occupies 51 seconds, terminal-crimping at Step 7 also occupies 51 seconds, terminal-crimping at Step 8 occupies 36 seconds, and Step 9 without crimping operation occupies 0 second. Terminal-inserting at Step 10 occupies 63 seconds, terminal-inserting at Step 11 also occupies 63 seconds, and removing the temporary binding unit B from the wire lay-out board at Step 12 occupies 40 seconds. The temporary binding unit C consists of seventeen electric wires, and a time occupied on fabricating it at Steps 1 to 12 is stated as follows; six of the electric wires are laid out on a wire lay-out board at Step 1 in 57 seconds, six of the electric wires are laid out on the wire lay-out board at Step 2 in 57 seconds, and the remaining five electric wires are laid out on the wire lay-out board at Step 3 in 48 seconds. All the ends of the electric wires are stripped at Steps 4 and 5 in 51 seconds, respectively, and terminals are pressed in crimp contact at Steps 6 to 9; these steps occupy 47 seconds, 44 seconds, 11 seconds, and 22 seconds, respectively. Furthermore, a time occupied on inserting terminals at each of Steps 10 and 11 is 57 seconds. Removing step at the final stage occupies 40 seconds. The temporary binding unit D consists of twenty-five electric wires, and nine of them are laid out on a wire lay-out board in Step 1 in 86 seconds. Eight of the electric wires are laid out on the wire lay-out board at Step 2 in 76 seconds, and the remaining eight electric wires are laid out on the wire lay-out board at Step 3 in 76 seconds. 75 seconds is occupied on stripping sheaths at the ends of the electric wires at each of Steps 4 and 5. Terminals are pressed in crimp contact at Steps 6 to 9, and the terminals used in this process vary in number from step to step; it takes 51 seconds at Step 6, 47 seconds at Step 7, 62 seconds at Step 8, and 22 seconds at Step 9. 83 seconds is occupied on terminal-inserting at each of Steps 10 and 11, and 40 seconds is occupied on finally removing the temporary binding unit D from the wire lay-out board at Step 12. A case where the above-mentioned temporary binding units A, B, C and D are fabricated on the basis of mixed flow production is possible. At the beginning of the mixed flow production, for example, the wire lay-out board "a" used for fabricating the temporary binding unit A is set in Step 12, the wire lay-out board "b" used for fabricating the temporary binding unit B is set in Step 11, the wire lay-out board "c" for fabricating the temporary binding unit C is set in Step 10, and the wire layout board "d" for fabricating the temporary binding unit D is set in Step 9. Also set are the wire lay-out board "a" in Step 8, the wire lay-out board "b" in Step 7, the wire lay-out board "c" in Step 6, the wire lay-out board "a" in Step 5, the wire lay-out board "a" in Step 4, the wire lay-out board "b" in Step 3, the wire lay-out board "c" in Step 2, and the wire lay-out board "d" in Step 1, respectively. The mixed flow production of the temporary binding units A, B, C and D are commenced under such a condition. Table 5 presents a time occupied on each stage in fabricating the four temporary binding units A, B, C and D on the basis of mixed flow production. As will be recognized in Table 5, after a sequence of process steps in each of Stages S1 to S4 are all completed, trains of the four wire lay-out boards proceed by one step and then undergo another sequence of process steps in the next one of the stages. Hence, regarding a state of each process step, the round of stages S1 to S4 are repeated in order like S1 → S2 → S3 → S4 → S1 → S2 → and so forth. Thus, the step occupying the longest processing time at Stage 1 is Step 1 which occupies 86 seconds. Adding 6 seconds for the conveyance to the subsequent step, 92 seconds is occupied on Step 1. The step occupying the longest processing time at Stage 2 is Step 10 which occupies 83 seconds. Adding 6 seconds for the conveyance to the subsequent step, 89 seconds is occupied on Step 10. The step occupying the longest processing time at Stage 3 is Step 11 which occupies 83 seconds. Adding 6 seconds for the conveyance to the subsequent step, 89 seconds is occupied on Step 11. The step occupying the longest processing time at Stage 4 is Step 4 which occupies 75 seconds. Adding 6 seconds for the conveyance to the subsequent step, 81 seconds is occupied on Step 4. Thus, a set of the temporary binding units A, B, C and D are finished in a cycle type of the total of the longest processing times at Stage S1 to S4, 92 sec. + 89 sec. + 89 sec. + 81 sec. = 351 sec., in this wiring harness fabrication line. Assuming that the wiring harness fabrication line is operated 20 hours a day, the production per day is obtained by the following equation: 20 x 3600 x 0.8 (operation rate) ÷ 351 sec. = 164 sets The production per month under the condition that the wiring harness fabrication line is operated 20 days a month is obtained as follows: 164 sets x 20 days = 3280 sets Also, as has been described, the productive efficiency in the fabrication line can be further enhanced without buffers if the number of the modules of each process step in the fabrication line can be increased. The increase of the modules in number may be performed under such a standard that a processing time of the step which occupies the longest one compared with a processing time occupied on any other step should be even off. Specifically, in the case where there are two of the terminal-crimping steps each of which occupies a processing time longer than the processing time of any other process step, the number of the modules of the terminal-crimping steps may be increased from two to three or four so as to divide the total processing time of the terminal-crimping steps into three or four, and a processing time per step can be decreased. This allows the processing time occupied on one of the terminal-crimping steps to be almost equal to the processing time on any other process step. In this way, the productive efficiency in the wiring harness fabrication line can be enhanced. Although a case where no buffer is incorporated has been presented in the context of the description of the preferred embodiment of the present invention, buffers may be interposed between any of the following step pairs; the steps 3 and 4, the steps 5 and 6, the steps 9 and 10, and the steps 11 and 12, so that the productive efficiency in this fabrication line can be further enhanced. As previously mentioned, the interposition of the buffers permits the wire lay-out board conveying cycle to be determined based upon the step occupying the longest processing time. As shown in Fig. 4, the total processing time occupied on fabricating the temporary binding units A, B, C and D at Step 1 is as the longest as 239 seconds, and therefore, the four temporary binding units A, B, C and D can be fabricated in a cycle time as expressed as follows: 239 + (6 x 4) = 249 sec. where the time occupied on conveying the wire lay-out board between any adjacent steps is added to the total fabrication time. Thus, assuming that the fabrication line is operative twenty hours a day, the production per day can be expressed as follows: 20 x 3600 sec. x 0.8 (operation rate) ÷ 249 = 231 sets assuming that the line is operative twenty days a month, the production per month can be expressed as follows: 231 sets x 20 days = 4626 sets Compared with a case where the buffers are not incorporated, an increase in production can be expected by 67 sets per day or 1346 sets per month. Incorporating the buffers in the wiring harness fabrication line permits the productive efficiency to be further enhanced. The wiring harness fabrication line as previously mentioned is disclosed herein as an example, and therefore, additional steps such as a check step may be incorporated besides the above-mentioned steps of wire laying out, stripping, pressing in crimp-style contact, inserting a terminal, and removing a temporary binding unit. Also, the wiring harness of model number X consisting of the temporary binding units A, B, C and D in the above embodiment is set forth only as an example. Thus, the fabrication line of the present invention is adjustable to any model number of wiring harness and is operable soon and effectively even if a variety of wiring harnesses of different model numbers must be fabricated. Thus, the present invention provides an improved wiring harness fabrication line capable of effectively fabricating wiring harnesses by changing the number of steps incorporated therein depending upon the model number of the desired wiring harness.

Claims: An automated wiring harness fabricating apparatus comprising a number of modules arranged in series and through which wire lay-out boards (9) are conveyed in series, wherein said number of modules comprise groups of one or more of the following modules arranged together in series: a wire laying out step module (1) to perform a wire laying out step of laying out electric wires coated with insulating sheaths in a laying out array and cutting to a measured length, a stripping step module (3) to perform a stripping step of stripping the insulating sheaths at the ends of the electric wires, a crimping step module (5) to perform a crimping step of pressing terminals together with the bared ends of the electric wires in crimp contact, and an inserting step module (7) to perform an inserting step of inserting into connectors the terminals in crimp contact with the ends of the electric wires. An automated wiring harness fabricating system according to claim 1, wherein each of said modules has common elements which comprise: a base frame (21), and a conveyor apparatus (22) mounted on said base frame (21) for conveying said wire lay-out boards (9); said conveyor apparatus (22) having a main conveyer element extending through almost the full extension of said base frame (21), and a projecting element (23) extending from an edge of said base frame (21) and intruding into the base frame of the adjacent module connected on the side proximate to the projecting element. An automated wiring harness fabricating system according to claim 2, wherein, in any adjacent ones of said modules connected to each other, the conveyor apparatus (22) in the first one of the adjacent modules is mounted on a front half of said base frame (21) about the extension of the base frame orthogonal to a wire lay-out board conveying direction while the conveyor apparatus (22) in the second one of the adjacent modules is mounted on a rear half of the base (21) about the extension of the base frame orthogonal to the wire lay-out board conveying direction, whereby the projecting element (23) of the conveyor apparatus (22) in the first module can partially overlap with the main conveyor element of the conveyor apparatus (22) in the second module connected to the first module in parallel with each other so as not to bump against or interfere with the main conveyor element. An automated wiring harness fabricating system according to claim 2 or claim 3, wherein said conveyor apparatus (22) includes a movable element (30) reciprocally movable in the wire lay-out board conveying direction and reverse direction to it, and positioning pins (39a, 39b) provided in said movable element (30) for positioning and holding the conveyed wire lay-out board (9). An automated wiring harness fabricating system according to claim 4, wherein said movable element (30) has an extension of a specified size in a direction along its movement, and there are two of said positioning pins (39a, 39b) at a specified interval in the direction along the movement of the movable element (30). An automated wiring harness fabricating system according to claim 4 or claim 5, wherein said positioning pins (39a, 39b) are alternatively switched between a state where they protrude from said movable element (30) so as to fit to the conveyed wire lay-out board (9) and a state where they neither protrude from said movable element (30) nor fit to the wire lay-out board (9). An automated wiring harness fabricating system according to any of claims 4 to 6, wherein said wire lay-out boards (9) have feed holes (45, 46) in their reverse side with which the positioning pins (39a, 39b) provided in said movable element (30) can engage. An automated wiring harness fabricating system according to claim 7, wherein said wire lay-out boards (9) include: a base plate (52); and a pin board (53) detachably fixed to the base plate (52) and having a plurality of laying out pins (54) planted on its surface to hitch thereround an electric wire arranged in a laying out array, said feed holes (45, 46) being formed in the reverse side of the base plate (52). An automated wiring harness fabricating system according to any of claims 1 to 8, further comprising a buffer module (11) interposed between predetermined first and second ones of said modules connected to one another, temporarily storing on standby the wire lay-out board (9) transferred from the preceding first module, and feeding the wire lay-out board (9) to the succeeding second module at a specified timing. An automated wiring harness fabricating system according to claim 9, wherein said buffer module (11) includes a base frame (21), and a conveyor apparatus (22) mounted on said base frame (21) for conveying said wire lay-out boards (9), said conveyor apparatus (22) having a main conveyer element extending through almost the full extension of said base frame (21), and a projecting element (23) running out of an edge of said base frame (21) and intruding into either the base frame of the preceding first module or the base frame of the succeeding second module. A method of organizing an automated wiring harness fabricating system, comprising conveying wire lay-out boards (9) through a number of steps in series, said number of steps comprising groups of one or more of the following steps in series: a wire laying out step of laying out electric wires coated with insulating sheaths in a laying out array and cutting to a measured length, a stripping step module arranged for of stripping the insulating sheaths at ends of the electric wires, a crimping step of pressing terminals together with the bared ends of the electric wires in crimp contact, and an inserting step of inserting into connectors the terminals in crimp contact with the ends of the electric wires. A method of organizing an automated wiring harness fabricating system according to claim 11, further comprising a buffer module interposed between the final module at specified preceding first one of said steps and the initial module at the second step succeeding to said first preceding step, temporarily storing on standby a wire lay-out board transferred from the last module at the preceding first module, and feeding the wire lay-out board to the initial module at the succeeding second step at a specified timing.

Inventors: GOTOH AKIRA, ITOH TOMOKAZU, KOBAYASHI TAKASHI, NISHIDE YUTAKA, OGAWA FUJIO, SAKUMA TEIJI, TAKENAMI YOSHIO, UEDA KOICHI, GOTOH, AKIRA, ITOH, TOMOKAZU, KOBAYASHI, TAKASHI, NISHIDE, YUTAKA, OGAWA, FUJIO, SAKUMA, TEIJI, TAKENAMI, YOSHIO, UEDA, KOICHI, Gotoh, Akira, c/o Osaka Works of, Itoh, Tomokazu, c/o Sumitomo Wiring Syst. Ltd., Kobayashi, Takashi, c/o Sumitomo Wiring Syst. Ltd., Nishide, Yutaka, c/o Osaka Works of, Ogawa, Fujio, c/o Sumitomo Wiring Syst. Ltd., Sakuma, Teiji, c/o Sumitomo Wiring Syst. Ltd., Takenami, Yoshio, c/o Sumitomo Wiring Syst. Ltd., Ueda, Koichi, c/o Osaka Works of
Applicants: SUMITOMO ELECTRIC INDUSTRIES, SUMITOMO WIRING SYSTEMS, SUMITOMO ELECTRIC INDUSTRIES, LTD., SUMITOMO WIRING SYSTEMS, LTD.
Application year: 1993
Main classification: H01R43
IPC codes: H01R43