Wire printing method and apparatus

Abstract: [Object] To provide a printing apparatus for precisely applying printing for identification to wires connected with connectors without causing any displacement of position and orientation. [Solution] A printing apparatus is provided with a palette 1 which is moved while being guided by slide rails 6, a wire receiving portion 2 on which wires 21 drawn from a connector 20 are placed, a wire correcting device 3, and a holder 4. The wire 21 fed to a marking section is pressed from above and is straightened in its longitudinal direction by the correcting device 3. The straightened wire 21 is further held in the center of the marking section by the holder 4. In this state, printing is applied to the wire 21 by a laser marker 5.

Description: The present invention relates to a method for applying printing or marking for identification to wires connected with a connector in the production process of a wiring harness preferably using a non-contact type printing apparatus such as a laser marker, and a wire printing apparatus. In the case of connecting a plurality of wires by one connector, the respective wires are generally colored in different colors so as to be individually identifiable. This method is disadvantageous in view of productivity and costs because it increases kinds of wires to be produced. In view thereof, it has been started to print characters and/or marks on wires for identification while coloring the wires in the same color. In this case, there has been adopted such a method according to which printing is applied to the wires during a wire measuring operation and, then, the wires are cut and have terminals mounted to be inserted into a connector housing. If printing is applied during the wire measuring operation, the wire measuring operation needs to be stopped every time printing is applied to the wire, resulting in a reduced production efficiency and a reduced output or turnout due to a loss of time. Further, if the terminal is mounted on the wire and inserted into the connector housing after printing, the position and direction of printing on the wire drawn from the connector may be displaced. Accordingly, if the position and direction of printing are specified, such displacements need to be corrected beforehand, which increases a wasteful operation. Document JP11027817, discloses: a wire printing method, comprising the steps of: feeding one or more wires connected with a connector to a marking section together with the connector at least partly supported by a palette for conveyance, and applying§ printing or marking for identification to the wire (21) in this state by a printing device provided in or near the marking section, and a wire printing apparatus, comprising: a palette for holding a connector such that the connector can be fed in a direction at an angle different from 0 DEG or 180 DEG , preferably substantially normal to a wire drawing direction from the connector, and a printing or marking device provided substantially above or near a marking section, where printing can be applied to the wire by the printing device. An object of the present invention is to solve the above problems and improve the productivity of a wiring harness. This object is solved according to the invention by a wire printing method according to claim 1 and by a wire printing apparatus according to claim 2. Preferred embodiments of the invention are subject of the dependent claims. According to the invention, there is provided a wire printing method, comprising the steps of: feeding one or more wires connected with a connector to a marking section together with the connector at least partly supported by a palette or holder for conveyance, at least partly pulling the wire drawn from the connector substantially straight in the marking section and holding it in the marking section, and applying printing or marking for identification to the wire in this state by a printing device provided in or near the marking section. According to a preferred embodiment, there is provided a wire printing method, comprising the steps of: feeding wires connected with a connector to a marking section together with the connector supported by a palette for conveyance, pulling the wire drawn from the connector straight in the marking section and holding it in the center of the marking section, and applying printing for identification to an insulation coating of the wire in this state by a non-contact type printing device provided in the marking section. Since printing is applied to the wires connected with the connector in the present invention, it can be done without stopping a wire measuring operation, thereby eliminating a loss of time. In order to securely apply printing or marking without displacing the position and orientation of the wires, the printing apparatus is constructed as follows. According to the invention, there is provided a wire printing apparatus, comprising: a palette or holder for holding a connector such that the connector can be fed in a direction at an angle different from 0° or 180°, preferably substantially normal to a wire drawing direction from the connector, a wire receiving portion or table on which portions of wires drawn from the connector on the palette are substantially placeable, a wire correcting device including an elevating or moving mechanism and an advancing mechanism, a holder including an elevating or moving mechanism, and a printing or marking device provided substantially above or near a marking section, wherein the wire correcting device is moved to press the wire fed to the marking section and is advanced in a direction away from the connector to at least partly substantially straighten the wire on the wire receiving portion in the wire drawing direction from the connector, the holder can be moved to hold the substantially straightened wire in the marking section, and printing can be applied to the wire by the printing device in this state. According to a preferred embodiment of the invention, the printing device is of the non-contact type. Specifically, the printing apparatus comprises: a palette for holding a connector such that the connector can be fed in a direction normal to a wire drawing direction from the connector, a wire receiving portion on which ends of wires drawn from the connector on the palette are placed, a wire correcting device including an elevating mechanism and an advancing mechanism, a holder including an elevating mechanism, and a non-contact type printing apparatus provided above a marking section, wherein the wire correcting device is lowered to press the wire fed to the marking section from above and is advanced in a direction away from the connector to straighten the wire on the table in the wire drawing direction from the connector, the holder is then lowered to hold the straightened wire in the center of the marking section, and printing is applied to the wire by the non-contact type printing device in this state. The wire connected with the connector is buckled or bent, and printing cannot be directly applied thereto since it cannot be precisely positioned. Thus, according to the present invention, the wire drawn from the connector is pulled to be straightened by the wire correcting device, and printing is applied after the straightened wire is held in the center of the marking section by the holder. With such an arrangement, no omission of printing occurs due to the displacement of the wire, and the position and orientation of printing can be constantly maintained. Thus, it is not necessary to correct the displacement even when the position and orientation of printing are specified. Preferably, a plurality of wires drawn from the connector are successively fed to the marking section by moving the palette in the direction at an angle different from 0° or 180°, preferably substantially normal to the wire drawing direction from the connector. This apparatus may additionally comprise a moving mechanism for moving the palette holding the connector in the direction normal to the wire drawing direction from the connector when a plurality of wires drawn from the connector are successively fed to the marking section. Accordingly, in the printing apparatus in which a plurality of wires are successively fed to the marking section by conveying the connector and the wires by the palette, printing can be continuously applied. Preferably, the wire correcting device comprises a roller preferably formed with a substantially V-shaped groove which roller is rotated in a wire straightening direction, wherein the wire can be substantially straightened while preferably being centered by the surface of the groove of the roller. Also preferably, the wire correcting device comprises a roller having no groove which roller is rotated in a wire straightening direction and the wire is preferably pushed into a substantially V-shaped groove formed in the wire receiving portion by the roller to be centered. Further preferably, the wire correcting device comprises two eccentrically arranged rollers mounted on a holding member having a pivotal center displaced from the centers of rotation of the two rollers, so that the two wires can be simultaneously pulled to enable simultaneous application of printing thereto. If such a wire correcting device comprises two eccentrically arranged rollers mounted on a holding member having a pivotal center displaced from the centers of rotation of the two rollers, two wires can be simultaneously pulled to enable simultaneous application of printing thereto. Thereby, a more preferable apparatus can be realized. The wire correcting device preferably comprises a roller which causes no fretting in order to prevent the wires from being damaged. However, if the wire correcting device is provided with a soft pad and substantially V-shaped grooves for centering, the wires can also be straightened by a method for pressing the wires by the soft pad while lightly bringing the surfaces of the substantially V-shaped grooves into contact with the wires. In the printing apparatus in which the wire correcting device comprises a roller, the wires are not scratched. Further, in the printing apparatus in which the two rollers are mounted on the holding member having a pivotal center displaced from the centers of rotation of the rollers, two wires having the same diameter or different diameters can be simultaneously handled, thereby improving an operation efficiency. Still further preferably, a chuck for gripping the substantially straightened wire from opposite sides is used as the holder, a brush operable with the wire correcting device is further provided to brush gripping surfaces of the chuck by substantially passing therebetween or thereon during advancing and retracting movements of the wire correcting device. Besides, it is preferable to use chuck for gripping the substantially straightened wire from opposite sides as the holder, and to provide a brush which is operable with the wire correcting device and brushes gripping surfaces of the chuck by passing therebetween during advancing and retracting movements of the wire correcting device preferably when a laser marker is used as the printing device. It is also preferable to provide a sensor for detecting the wire positioned in the marking section so that printing can be applied by the printing device in accordance with a detection signal from the sensor. Further preferably, the holder comprises at least one pressing element for holding the substantially straightened wire(s) by pressing it or them and is formed with a through hole in or through which printing can be applied. If printing is applied in a hole extending through the holder, the straightened wire can be held by being pressed from above by the holder. This construction is particularly effective when printing is simultaneously applied to a plurality of wires. It enables the respective wires to be held at once by one holder unlike the chuck, and is not subject to restriction on installation space, etc. In the case that the printing or marking device is or comprises a laser marker and the holder is a chuck, cinders of the insulation coating adhere to the gripping surfaces of the chuck when characters or marks are made by burning the insulation coating of the wire by a laser beam from the laser marker. However, if the printing apparatus is provided with the brush, the adhered matters can be removed by brushing the gripping surfaces before the chuck grips a next wire. Therefore, the wire is not smeared by the transfer of the adhered matters from the gripping surfaces. Further, in the printing apparatus in which printing is applied to the wire by the laser marker after the wire positioned to the marking section is detected by the sensor, an undesirable event where a laser beam is emitted in the absence of the wire, thereby preventing the table from being damaged by the laser beam. These and other objects, features and advantages of the present invention will become apparent upon reading of the following detailed description of preferred embodiments and accompanying drawings. It should be understood that even though embodiments may be separately described, single features thereof may be combined to additional embodiments. FIG. 1 is a side view showing a printing apparatus according to one embodiment of the invention, FIG. 2 is an enlarged side view showing an essential portion of the printing apparatus, FIG. 3 is an enlarged plan view showing the essential portion of the printing apparatus, FIG. 4 is an enlarged front view showing the essential portion of the printing apparatus, FIG. 5 is a detailed diagram of a portion along V-V of FIG. 3, FIG. 6 is an enlarged front view of a correcting device, FIG. 7 is a plan view showing a simplified example of wires connected with connectors, FIG. 8 is a front view showing a wire correcting operation by the correcting device, FIG. 9 is a front view showing a state of a corrected wire held by a chuck, FIG. 10 is a side view of a printing apparatus according to another embodiment, FIG. 11 is a front view of the apparatus of FIG. 10, FIG. 12 is a plan view showing an essential portion of the apparatus of FIG. 10, FIG. 13(a) is a plan view of a wire correcting device using a pair of rollers, FIG. 13(b) is a side view of the wire correcting device of FIG. 13(a), FIG. 13(c) is a front view of the wire correcting device of FIG. 13(a), and FIG. 13(d) is a perspective view of a holding shaft, FIG. 14(a) is a plan view of a holed holder, FIG. 14(b) is a vertical sectional side view of the holed holder, and FIG. 14(c) is an enlarged view of the holed holder, and FIG. 15(a) is a perspective view showing another example of the wire correcting device turned upside down, and FIG. 15(b) is a side view of the wire correcting device of FIG. 15(a). FIGS. 1 to 6 show one preferred embodiment of a printing apparatus according to the present invention. This printing apparatus is provided with a palette or holder 1 shown in FIGS. 1 and 2 for conveying a connector while holding it, a feeding mechanism (not shown) for laterally moving the palette 1 (or moving it in a direction at an angle different from 0° or 180°, preferably substantially normal to a conveying direction), a wire receiving portion or table 2 on which ends of wires connected with a connector 20 are placed, a wire correcting device 3 and a holder or chuck 4 provided above or on the wire receiving portion 2, and a marking or printing device such as a laser marker 5 provided above or near a marking section. The palette 1 is conveyed from a previous station to a printing station by being guided by slide rails 6 shown in FIG. 2. In a previous operation step, the wires are measured, cut and/or connected with the connector. In the connecting operation, a method for mounting a crimping terminal with a wire after an insulation coating at an end of the wire is stripped to expose a conductor, and inserting the crimping terminal into a connector set in the palette 1 and/or a method for pressing an end of a wire into an insulation-displacement terminal inserted beforehand in a connector to electrically connect contact pieces of the terminal and a conductor by cutting an insulation coating of the wire by the contact pieces and then crimping barrels of the terminal to hold the insulation coating of the wire is adopted to connect the connector. FIG. 7 shows an example (20, 21 in FIG. 7 are connectors and wires, respectively) of a final wiring harness obtained by connecting wires with connectors. The palettes 1 are moved to the printing station while carrying a product in this mode or way. The feeding mechanism for moving the palettes 1 in a feeding or moving direction FD of an arrow of FIG. 7 may be a known mechanism for, e.g. rotating a ball screw by means of a servo motor to move a slider engaged with the ball screw. The slider of this feeding mechanism is or can be coupled to the palette 1 via a detachable coupling device to move the palette 1. The palette 1 is or can be detached from the slider of the feeding mechanism after printing or marking and detachment of the connector from the palette 1 and is returned to a starting end of a processing line via a return path (not shown). The wire receiving portion or table 2 is provided along a movement path (forward path) of the palette 1, and the wires 21 are or can be corrected by the correcting device 3 on the wire receiving portion 2. The correcting device 3 includes an elevating or moving mechanism 7 and an advancing mechanism 8 shown in FIG. 5. The elevating mechanism 7 moves a movable frame 7a upward and downward (or toward and away from the movement path in a direction at an angle different from 0° or 180° thereto) by means of an air cylinder 7b. Identified by 7c is an adjusting device for adjusting distances or ranges of upward and downward movements of the movable frame 7a. When the movable frame 7a reaches top and bottom end positions, a stopper 7d mounted on the movable frame 7a comes into contact with an adjustment bolt of the adjusting device 7c. The air cylinder 7b and the adjusting device 7c are mounted on a fixed frame 9. The advancing mechanism 8 includes an air cylinder 8a mounted on the movable frame 7a, a movable arm 8b which is pushed and pulled by the cylinder 8a, a stopper 8c for stopping the movable arm 8b at an advance end position, and an adjusting device 8d for adjusting a stop position or a movable range. The adjusting device 8d may be provided on the stopper 8c. The correcting device 3 includes a roller 3a formed with a preferably substantially V-shaped groove shown in FIG. 6 and a preferably substantially horizontal shaft 3b mounted on the movable arm 8b. The roller 3a is rotatably supported on the horizontal shaft 3b. This roller 3a can cope with a change in the size of the wires because it performs correction and centering (or corrects the position and orientation) of the wire by the substantially V-shaped groove. A brush 10 tapered toward its leading end is vertically mounted on the movable arm 8b. The holder or chuck 4 preferably is an air chuck for gripping the wire 21 from opposite sides by opening and closing a pair of transversely arranged parallel hands or grippers 4a, and includes an elevating or moving mechanism 11 shown in FIG. 2. The elevating mechanism 11 has the same or similar construction as the elevating mechanism 7 of the correcting device 3. Identified by 12 in FIGS. 2 and 3 is an optical fiber sensor for detecting a wire, which sensor is supported on the fixed frame 9. The sensor 12, the roller 3a, the brush 10 and the substantially parallel hands 4a of the chuck 4 are arranged on a center line C (see FIG. 4) of the marking section. The laser marker 5 is provided on the fixed frame 9 via a position adjusting mechanism 13 as shown in FIG. 1. The position adjusting mechanism 13 moves or allows a change of the position of a supporting plate 13a to front, back, left and right within a range of e.g. about 10 mm to precisely position an emission center P of a laser beam shown in FIGS. 1, 2 and 5. Identified by 14, 15' in FIGS. 1 and 4 are a turn buckle as a preferred adjusting means for adjusting the height position of the laser marker 5 and a safety cover, respectively. In the printing apparatus constructed as above, when the palette 1 is moved to or near and stopped at or near the printing station, the correcting device 3 is lowered to press the wire 21 drawn from the connector 20 preferably substantially from above as shown in FIG. 8. The correcting device 3 is rotated or moved in a direction away from the connector 20 to straighten the wire 21. Subsequently, the chuck 4 is lowered when the correcting device 3 is advanced to and stopped at a position shown in phantom line in FIG. 2, and the parallel hands 4a are closed to substantially grip the wire 21 from opposite sides as shown in FIG. 9. At this time, the wire 21 is precisely positioned on the center line C of the marking section and printing is made thereon by the laser marker 5 in this state. Accordingly, there is no problem of printing omission and displacement. Upon completion of printing or marking, the parallel hands 4a are opened to substantially return the chuck 4 and then the correcting device 3 is substantially retracted. Gripping surfaces of the parallel hands 4a are cleaned by the brush 10 during the retracting and advancing movements of the correcting device 3 to remove cinders of the insulation coating adhered to the gripping surfaces. The correcting device 3 is returned to an initial position by moving backward after moving upward. In the above procedure, printing on the first wire is completed. Thereafter, the feeding mechanism moves the palette 1 by a specified (predetermined or predeterminable) distance to set the second wire in the marking section. The above operation is repeated for the second and subsequent wires. In this way, all the wires are printed for identification. FIGS. 10 to 14 show a printing apparatus according to a second preferred embodiment. This apparatus differs from the apparatus of FIGS. 1 to 6 in that substantially V-shaped grooves for centering wires are formed in the wire receiving portion 2, a wire correcting device 3A for simultaneously pressing two wires 21 is used, a holder 4A for holding the wires 21 by pressing them from above is used, and a pressing device 16 for pushing drawn ends of the wires 21 from a connector down is used. The elevating mechanisms 7, 11 and the advancing mechanism 8 have the same or similar functions as those described above although they have different configurations. The wire correcting device 3A is constructed, as shown in FIG. 13(a), by mounting two eccentrically arranged rollers 3c, 3d on a holding shaft 3e having its center of rotation O in a position displaced from the centers of rotation of the two rollers 3c, 3d. The wire correcting device 3A operates such that, when there is a difference in the diameters of two wires 21 to be pressed by the rollers 3c, 3d, the holding shaft 3e is rotated to automatically adjust the heights of pressing points by the rollers 3c, 3d in conformity with the diameters of the wires 21. Accordingly, the wire correcting device 3A can securely straighten the two wires 21 by pressing them even if the diameters thereof differ. Although the rollers 3c, 3d shown in FIGS. 13(a) to 13(d) are not formed with a groove, rollers formed with a groove may be used. In such a case, the substantially V-shaped grooves 15 formed in the wire receiving portion 2 may be omitted. The holder 4A has a hole 4b vertically extending therethrough and pressing elements 4c for pressingly holding the corrected wires 21 by positioning them preferably by substantially V-shaped grooves formed in their bottom surfaces. The pressing elements 4c are so mounted on a holed frame 4d moved upward and downward by the elevating mechanism 11 as to be vertically movable (or movable towards and away from the wire receiving portion 2) while being biased downward by springs 4e. When a thick wire is pressed, the pressing elements 4c compress the springs 4e to escape upward. The pressing elements 4c are each formed with a slit 4f for exposing a printing surface of the wire 21 to the outside via the hole 4b, and the two wires 21 are simultaneously printed or marked by laser markers 5A (see FIG. 10) in the slits 4f. FIG. 15 is a wire correcting device 3B having no roller. This wire correcting device 3B is such that a sponge pad 3h and a centering claw 3i are formed on the bottom surface of a main body 3g moved by an elevating mechanism and an advancing mechanism (both not shown) and formed with an opening 3f through which a laser beam is projected, and the wires 21 on the wire receiving portion 2 are pressed by the sponge pad 3h while being centered by substantially V-shaped grooves formed in the centering claw 3i. Such a correcting device can also pull and align the wires in the centers of marking points. Characters printed on the wires are preferably difficult to erase. In this respect, a printing device used is preferably a laser marker shown in the drawings. However, if it is not particularly specified, a printing device of the ink-jet type may also be used. As described above, according to the inventive printing method and printing apparatus, the wires connected with the connector are fixed by the connector set in the wire holder, the buckled or bent wires are straightened using the wire correcting device in this state, and printing is applied while the straightened wires are positioned and held by the chuck. Thus, it is not necessary to stop the wire measuring operation every time printing is applied, and productivity can be improved by eliminating a loss of time. Since the position and orientation of printing are constant, it is not necessary to correct them and productivity can be further improved. The wires are neither smeared nor scratched in the apparatus having the wire correcting device realized by the roller formed with a V-shaped groove or provided with the brush for cleaning the gripping surface. If the two rollers are so provided as to automatically adjust the heights of their pressing points, two wires can be simultaneously printed regardless of whether they have the same diameter or different diameters, which leads to an improved productivity. Further, the apparatus provided with the wire detecting sensor can be better protected since a laser beam for printing is not projected onto the wire receiving portion. LIST OF REFERENCE NUMERALS 1 palette 2 wire receiving portion 3, 3A, 3B wire correcting device 3a roller formed with a V-shaped groove 4, 4A holder 4a parallel hand 5, 5A laser marker 6 slide rail 7 elevating mechanism 8 advancing mechanism 9 fixed frame 10 brush 11 elevating mechanism 12 wire detecting sensor 15 V-shaped groove 16 pressing device 20 connector 21 wire C center line of a marking section P emission center of a laser beam

Claims: A wire printing method, comprising the steps of: feeding one or more wires (21) connected with a connector (20) to a marking section together with the connector (20) the connector being at least partly supported by a palette (1) for conveyance, at least partly pulling the wire (21) drawn from the connector (20) substantially straight in the marking section and holding it in the marking section, and applying printing or marking for identification to the wire (21) in this state by a printing device provided in or near the marking section. A wire printing apparatus, comprising: a palette (1) for holding a connector (20) such that the connector can be fed in a direction (FD) at an angle different from 0° or 180°, preferably substantially normal to a wire drawing direction from the connector (20), a wire receiving portion (2) on which portions of wires (21) drawn from the connector (20) on the palette (1) are placeable, a wire correcting device (3; 3A; 3B) including an elevating mechanism (7) and an advancing mechanism (8), a holder (4; 4A) including an elevating mechanism (11), and a printing or marking device (5; 5A) provided substantially above or near a marking section, wherein the wire correcting device (3; 3A; 3B) is to be moved to press the wire (21) fed to the marking section and to be advanced in a direction away from the connector (20) to at least partly substantially straighten the wire (21) on the wire receiving portion (2) in the wire drawing direction from the connector (20), the holder (4; 4A) can be moved to hold the substantially straightened wire (21) in the marking section, and printing can be applied to the wire (21) by the printing device (5; 5A) in this state. A wire printing apparatus according to claim 2, wherein the printing device (5; 5A) is of the non-contact type. A wire printing apparatus according to claim 2 or 3, wherein a plurality of wires (21) drawn from the connector (20) are successively fed to the marking section by moving the palette (1) in the direction (FD) at an angle different from 0° or 180°, preferably substantially normal to the wire drawing direction from the connector (20). A wire printing apparatus according to any one of claims 2 to 4, wherein the wire correcting device (3) comprises at least one roller (3a) preferably formed with a substantially V-shaped groove which roller (3a) is rotated in a wire straightening direction, and the wire (21) can be substantially straightened while preferably being centered by the surface of the groove of the roller (3a). A wire printing apparatus according to any one of claims 2 to 5, wherein the wire correcting device (3A) comprises at least one roller (3c; 3d) preferably having no groove which roller (3c; 3d) is rotated in a wire straightening direction, and the wire (21) can be preferably pushed into a substantially V-shaped groove (15) formed in the wire receiving portion (2) by the roller (3c; 3d) to be substantially centered. A wire printing apparatus according to claim 5 or 6, wherein the wire correcting device (3A; 3B) comprises two eccentrically arranged rollers (3c, 3d) mounted on a holding member (3e) having a pivotal center displaced from the centers of rotation of the two rollers (3c, 3d), so that the two wires (21) can be simultaneously pulled to enable simultaneous application of printing thereto. A wire printing apparatus according to any one of claims 2 to 7, wherein a chuck (4) for gripping the substantially straightened wire (21) from opposite sides is used as the holder (4; 4A), a brush (10) operable with the wire correcting device (3; 3A; 3B) is further provided to brush gripping surfaces of the chuck (4) by substantially passing therebetween or thereon during advancing and retracting movements of the wire correcting device (3; 3A; 3B). A wire printing apparatus according to any one of claims 2 to 8, wherein the holder (4A) comprises at least one pressing element (4c; 16) for holding the substantially straightened wire(s) (21) by pressing it or them and is formed with a through hole (4d) in or through which printing can be applied. A wire printing apparatus according to any one of claims 2 to 9, wherein the printing or marking device (5; 5A) comprises a laser marker (5; 5A).

Inventors: HASHIMOTO KENJI, OTANI AKIHITO, HASHIMOTO, KENJI, OTANI, AKIHITO, Hashimoto, Kenji, Sumitomo Wiring Systems, Ltd., Otani, Akihito, Sumitomo Wiring Systems, Ltd.
Applicants: SUMITOMO WIRING SYSTEMS, SUMITOMO WIRING SYSTEMS, LTD.
Application year: 2000
Main classification: H01R43
IPC codes: H01B13, H01R43