CA1044575A

CA1044575A - Wire feeding apparatus and method

Info

Publication number: CA1044575A
Application number: CA270,294A
Authority: CA
Inventors: David E. Bickford; Matthew M. Sucheski; Earl W. Wagner; Robert K. Southard
Original assignee: AMP Inc
Current assignee: TE Connectivity Corp
Priority date: 1976-02-23
Filing date: 1977-01-24
Publication date: 1978-12-19
Also published as: DE2707624C2; FR2341509A1; JPS5942923B2; ES456148A1; BR7700876A; IT1085307B; FR2341509B1; GB1524788A; JPS52103686A; DE2707624A1

Abstract

ABSTRACT

A high speed wire feeding apparatus comprises a wire feed roll and pressure rolls, the wire feed roll being driven intermittently by a motor under the influence of control means which maintains a high and constant level of acceleration and deceleration at the beginning and end of the feeding cycle, the control means can be programmed to move the pressure rolls between wire feeding and non-wire-feeding positions, selectively, so that a bundle of wires having varying lengths can be produced.

Description

This invention relates to wire feeding apparatus and to a method of feeding wire.
According to one aspect of the invention, wire feeding apparatus comprises a wire feed roll arranged to be driven in rotation about its own axis, a plurality of pressure rolls each of which is rotatable about an axis which is parallel to that of the feed roll and control means for moving each of the pressure rolls between a wire feeding first position adjacent the feed roll and a non-wire-feeding second position remote from the feed roll, the control means being arranged selectively to move the pressure rolls ; 10 between their first and second positions and to start and stop the feed roll to determine the lengths of wire to be fed in accordance with a predetermined wire feeding programme.
According to another aspect of the invention, a method of feeding wire in accordance with a predetermined wire feeding programme, comprises ~' the steps of; guiding a plurality of wires each from a wire source to position the leading ends of the wires on a driven wire feed roll with each wire positioned between the feed roll and a pressure roll individual to that wire and which is spaced therefrom; selectively feeding the wires by moving ~` the pressure roll associated with each wire to be fed, into feeding contact therewith and repeatedly starting and stopping the feed roll to determine the lengths of wire to be fed in accordance with the predetermined wire feeding programme.
For a better understanding of the invention reference will now be made by way of example to the accompanying drawings in which:
Figure 1 is a perspective view of a first bundle of '`:':, -, .., . ~ .

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w1res;
Figure 2 is a diagrammatic plan view of wire feeding apparatus, comprising a wire feed roll;
Figure 3 is a sectional side view of wire feeding means of the apparatus of Figure 2; ~-Figures 4 is a view taken on the lines IV-IV of Figure 3 Figure 5 is a view taken on the lines V-V of Figure 3 with parts omitted and with parts superimposed and shown in plan view;
Pigures 6 and 6A form a block and schematic diagram of a control circuit for the apparatus, when these figures are joined along the lines A-A
therein, Figure 7 is a schematic wiring diagram of a motor drive system of the apparatus;
Pigure 8 is a diagram illustrating the steps to be carried out in feeding wires to produce a bundle of five wires as shown in Figure 1, the wires having different predetermined lengths, Pigure 8A is a diagram illustrating the steps to be carried out in feeding wires to produce a second bundle of wires;
I Pigure 9 is a graph illustrating the speed of a wire feet roll of ¦ 2a the apparatus during several feeding steps to produce the bundle of wires shown in Figure l;
Figure 10 is a diagramatic side view of a pressure roll and a feed roll in contact with a wire showing the forces acting on the wire during feeding of the wire; and Figure 11 is a graph illustrating comparative speed-time curves for electric drive motors coupled to wire feed rolls.
Figures 2 to 7 illustrate apparatus for producing bundle 12 ~Figure 1) of wires Wl to W5 fastened together by means of a tie 14, or example. As s shown, the wires of the bundle are of graduated length, the wire Wl being the shortest~ the wire W2 being the next shortest and so on. The wires may be ~ of different kinds or gauges as required. The right hand ~as seen in Figure 1), I ends of the wires are laterally aligned with each other. Such bundles of wires - 3.
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iS..~4~S75 are used in the manufacture of electrical harnesses, for example for automobileswashing machines or other appliances. Connecting terminals are crimped to the ends of the wires in the course of the harness making process.
As shown in Figure 2, the apparatus comprises wire feeding means 16, and electric drive motor 18, and control and programming means 20 which can be programmed to produce wire bundles comprising wires of different lengths.The wires are drawn from wire storage spools 22, 24, 26, 28 and 30 mounted on a common shat 32 and extend from the spools to the feeding means 16. The wlres fed from the means 16 are severcd by cutting blades 82 to provide a plurality of cut wire lengths which are subsequently secured together to form the bundle 12 by means of an applicator 86 for applying ties 14 about the severed wire lengths.
As shown in Figures 3 to 5 the feeding means 16 comprises a frame having a base 34 and parallel side walls 36 having bearings 40 for the shaft 38 of the motor 18, to which shaft is keyed a wire feed roll 42. The side walls 36 have recesses 46 (~igure 4) receiving lower wire guides 48 and 52 tFigure 3) and upper wire guides 50 and 54, the latter guides having parallel ~ spaced grooves 56 for pressure rolls 58a and 58e and wire clamping members 76, Y~ described below.
A separate pressure roll 58a to 58e is provided for each wire, each roll being received in one of the grooves 56 and being rotatably mounted on a pin 60 supported by a lever 62 comprising two spaced bars, as best seen in Figure 5. Each lever 62 extends rightwardly (as seen in Figure 3) from its - pin 60 beyond side walls 36 and is connected through an individual pivot pin ~YR 64 to an individual clevis 66 mounted on a piston rod of one of a plurality of piston-and-cylinder units 70a to 70e.
On the other side of its pin 60, each lever 62 is pivotted on a shaft 74, common to all the levers 62 and being mounted in extensions 36' ~Figure 5) of the side walls 36. A wire clamping member 76 is secured by a fastener 78 to the end of each lever 62 remote from its pivot pin 64 and extends into the associated groove 56. The levers 62 are normally in an extreme anti-clockwise (as seen in Figure 3) angular position about the shaft - 4.

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74 so that the clamping members 76 normally clamp the wires in the groves 56 against the ~ire guide 48, the pressure rolls 58a to 58e being thus held out of engagement with the wires so that the wires cannot be fed. The wires can be selectively fed by selectively actuating the units 70a to 70e to advance their piston rods to move the pressure rolls associated with the selected wires towards the feed roll 42 and into contact with these wires, the clamping member 76 associated with each of these pressure rollsJ being moved away from its wire, whereby the wire is driven when the motor 18 is started. It will be apparent from the above description that all the wires can be fed simultane-ously or an individual wire or a combination of wires can be fed by actuating the appropriate one, or ones, of the piston-and-cylinder units 70a to 70e.
A wire bundle 12 is produced by a series of wire feeding steps as illustrated in Figure 8. During the first feeding step, the pressure roll 58e is engaged with the wire W5 and the motor 18 is started, and run for a sufficient time to feed the wire W5 a distance equal to L5 minus L4, where L5 and L4 are the lengths of the wires W5 and W4 to be produced respectiv01y and the motor is then stopped. During the second feeding step, the motor is started again with the pressure rolls 58e and 58d ln contact with the wires W5 and W4 respectively and is run for a sufficient time to feed these wires a distance equal to L4 minus L3. During the third feeding step~ the wires W5, W4 and W3 are similarly fed a distance equal to L3 minus L2, while during the fourth feeding step the wires W5, W4, W3 and W2 are fed a distance equal to L2 minus Ll. In the fifth feeding step all the wires are fed by a distance Ll that is to say by the length of the wire Wl. The wires subsequently extend from the wire feeding means 16 with their leading ends positioned as shown in Figures 2 and 8 and are severed upstream of the feeding means 16 by the blades 82 as sho~n in Figure 2, so that the trailing ends of the severed ends are ... . .
' in alignment. The wires could of course be severed in such a way their trailing `~ ends are axially displaced from one another.

A control system of the apparatus described above will now be described with reference to Figures 6, 6A and 7. As shown in Figure 6A the system com-- prises a digital control device 108 which may be, for example, a model 1220 .~ .

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1~4~S75 digital computer manufactured by the Data General Company of Southboro MassO
UoSoA~ The control device 108 serves to receive signals from a plurality of sub-systems described below, to produce signals for transmission to the sub-systems, to operate the wire feeding means 16, and to coordinate the timing and the operation of various components of the apparatus. The control device 108 is therefore arranged to select the units 70a to 70e to be actuated and the sequence of their actuation, in response to signals from an operator control console 137 and is capable of performing arithmetic computations for example L2 minus Ll, required to produce a wire bundle of given form~
The control device 108 is connected at 106 to a control device interface in the form of a converter 104 for converting logic voltage signals of the device 108 into logic voltage and other signals for the sub-systems.
The converter 104 is thus a digital input-output device and may be for example of the type produced by the Data General Corporation mentioned above, under Model No. 56020 The lengths of the wires Wl to W5 is determined by setting five separate binary coded decimal thumb-wheel switches 88a, to d, 90a to d, 92a to d, 94a to d and 96a to d, of a wire length input device 101, each of these switches being capable of being set for four dlgits. The switches are connect-ed to common busses 98a to 98d, which are connected through logic gates 100 to the transitor-to-transitor logic input card 102 of the converter 104. The gates 100 are voltage level converters, since the switches of the device 101 operate at a higher voltage than the input card 1020 The converter 104 is also connected through a transi~or-to-transitor logic output card 109 thereof to the switches through a line 110 and individual selecting lines 112 connected to the individual switches for multiplying data from the switches of the device 101 to the busses 98a to 98d, so that the switches can be sequentially examined --by the control device 108. The lengths of the several wires Wl to W5 of the bundle can thus be determined simply by setting the switches of the device 101 so that the information stored therein is transmitted through the convert-er 104 to the device 108 which determines the optimum wire feeding sequence, upon the basis of such information~ The individual units 70a to 70e are lQ4~575 selectively actuable by solenoid operated air valves 114a to 114e coupled to ; a reed relay output section 120 of the converter 104, by lines 118, diodes 116 being connected in parallel with the solenoids, for noise suppression purposes.
` The console 137 comprises control switches for the apparatus. Some of these switches may be manual as exemplified by a switch 136 and a manual wire feed contol switch 135 described below.
Manual wire feed means are provided for feeding all the wires simultan-eously at a predetermined speed. These manual feed means are used primarily during setting-up the apparatus and comprise a reed relay output 129 of the converter 104, connected to a motor contro circuit 122 by lines 131. When ., .
the switch 135 is actuated, all the units 70a to 70e are actuated by the valves 114a-114e and the motor 18 is also energized. The reed relay output 129 serves to place the motor 18 under the manual control through the circuit 122.
The motor control circuit 122 is connected to a transitor-to-transitor logic output 130 of the converter 104 through a line 128. The circuit 122 receives command input signals, on the line 128 and transmits motor status t output data concerning the running time of the motor 18, through a line 124 to an input 126 of the converter 104 which converts 24 volt signals from the motor to 5 volt signals which are passed to the control device 108 via the connection 106. Since the motor 18 must be started and stopped very rapidly if the wires are accurately to be fed and so must be of low intertia, it is ~ preferably constituted by the printed circuit motor. The drive roll 42, in - particular, should be such that its inertia is suitably low. The speed of the motor 18 is monitored by a tacometer 166 (Figure 7) associated with a rotary encoder 170 for monitoring and angular displacement of the motor and thus the wire lengths fed.
The motor control circuit 122 receives data concerning the amount of , wire which is to be fed during each wire feeding step, through the line 128.
This data is stored in the circuit 122 during a wire feeding step, the control device 108 causing the motor 18 to rotate the feed roll 42 through 7.

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1~)4~575 the appropriate number of revolutions to feed the desired lengths of wire.
In order that the wire should be fed by the roll 42 as rapidly as possible, the motor 18 is arranged to be accelerated at a high and substant-ially constant rate, from start, to a normal operating speed and is then decelerated at a high and substantially constant rate until it is stopped. A
commercially available control means for achieving this is System 500 manufac-tured by Control System Research Incorporated of Pittsburg Pennsylvania USA.
- Such control means is shown in block form in Pigure 7.
As shown in ~igure 7, the control means comprises a buffer storage and synchranous counter device 142 which receives and stores information received through the line 128. Output lines 144 of the device 142 are connected to a digital-to analogue converter 146, the output 148 of which is in turn connect-ed to a square rooting circuit 150. The circuit 150 is connected through a line 52 to a feed back switching circui~ 154 having an output line 158 con-nected to a servo amplifier 160 which supplies power through a line 162 to the motor 18. The motor 18 has a tacometer 166 and an encoder 170 on its shaft. The tacometer 166 is connected back to the amplifier 160 by a line 168. The encoder 170 is connected through a line 171 to a driv~r 172 which is in turn connccted to a clock pulse generator 176 via a line 174, the generator 176 being connected to the device 142 via a line 178. The output of the driver 172 is connected to the circuit 154 through the line 174 and a line 175. The device 142 is also connected through a line 156 to the swit-ching circuit 154.
During a wire feeding operation, the buffer storage portlon of the device 142 receives data requiring a predetermined length of wire to be fed which in turn requires the motor 18 to perform a predetermined number of revolutions. The counter portion of the device 142 produces an error signal proportional to the amount of wire to be fed and which is passed through the lines 144 to the converter 146 the output of which is passed to the circuit 150 whose output is in turn passed to the circuit 154 via the line 152. The square rooting circuit 150 provides the required non-linear transformation to allow deceleration of the motor 18 to occur at the desired rate. Dur~ng the feeding of the wire, a signal is passed from the storage portion of the 8.

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- : . -:; .- , device 142 to the circuit 154 via the line 156 to cause it to pass the sign-al on the line 152 through the line 158 to the servo amplifier 160 which responds by supplying power to the line 162 to drive the motor 18 to rotate the feed roll 42 to feed the wire. The speed of the motor 18 is controlled by a servo loop comprising the tacometer 166 the line 168 and the servo-amplifier 160 and the motor 18.
During a wire feeding operation the encoder 170 generates signals indicating the number of revolutions that the motor 18 has made, these signals being amplified in the driver 172 and passed to the clock generator 176 and to the switching circuit 154. As the wire is being fed these signals are blocked in the switching circuit 154 so long as a final motor position signal on the line 156 indicates that there is still wire to be fed and the clock generator 176 supplies corresponding signals to the counter portion of the device 142, which signals decrement the buffer storage portion of the device 142 to update the counter portion as to the amount of wire which has been fed. The counter portion responds by appropriately changing the error signals supplied to the lines 144.
When the required length of wire has been fed, the inal position signal on the line 156 causes the circuit 154 to pass any signals emitted by the encoder 170 to the servo-amplifier 160. After the completing of the wire i feeding operation, the circuit 154, the amplifier 160, the motor 18 and the encoder 170 and the lines 171, 174 and 175 constitute a final motor position regulating loop in respect of the shaft of the motor 18 and thus of the feed ; roll 42, the motor position being equivalent to the length of wire fed.
:. These elements are connected so as to produce a high and substant-ially constant acceleration of the motor 18 until its normal operating speed has been reached. The digital control device 108 and the other control elements are arranged to cause deceleration of the motor 18 at a high and s substantially constant rate so that the motor 18 is stopped when the required length of wire ha~ been fed. Usually the acceleration of the motor 18 will not be precisely constant but will change somewhat as indicated by the full line in the graph of Figure 11 in which the ordinate is calibrated in cms.
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1(~44575 per second in respect of the wire velocity V and the abscisa in milliseconds in Tespect of the time t required for feeding of a wire length, L, of 254 cms. The broken line curve in Figure 11 illustrates the wire acceleration in wire feeding apparatus in which the acceleration of the feed motor is not controlled so as to provide substantially constant wire acceleration and deceleration.
As will appear from Figure 11, when the wire feeding means 16 is operated, the wire velocity increases initially at a substantially constant rate but the acceleration then reduces somewhat as the normal operating speed is approached. During deceleration, the decrease in the wire velocity is linear excepting towards the end of the deceleration portion of the wire feeding cycle.
When only a shor~ length of wire is being fed during a particular feeding step, the feed roll may not attain its normal steady state operating speed but will simply accelerate to some speed which is lower than the steady state speed and immediately thereafter decelerate until it comes to rest.
However, the acceleration and deceleration will be more nearly constant, then as illustrated in Figure 11, especially if the wire length to be ed is very ``( short, or example 7 cms.
Figure 9 shows idealized speed V against time t curves for the feed roll 42 during the successive feeding steps required to produce a bundle of the type shown in Figure 1 where the differences (L5L4 L4 L3 etc~ are relat-ively slight and shortest wire Ll is of a length which permits the feed roll to achieve its normal operating speed and maintain that speed for a signifi-cant time interval. The feed roll achieves its normal speed only while the length Ll is being fed but in all of the other feeding steps, the feed roll -~ merely accelerate to a lesser speed than said normal speed and decelerates to a stop. The deceleration part of each curve is slightly steeper than the acceleration part. lt is of interest to note that if Ll i5 ahout 254 cms. and the difference ~L5 - L4 etc) are of the order of 7.~2 cms., the total time required to feed the bundle is only about 2 seconds which includes the inter-vals between feeding steps.
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Figure 10 illustrates the frictional relationships which exist between a wire W being fed and feed the roll 42 and a pressure roll 58a to e.
The pressure roll is urged against the wire by a force Fn which can be set at any desired level. The forc0 of static friction Fs between the wire and the rolls is dependent upon Fn in accordance with the equation Ps = F where is the coefficient of friction.
The upper limit of acceleration when a given wire is fed is the highest level that will not result in slippage between the wire and the ~eed roll 42 and the magnitude of this level of acceleration is directily depend-ent upon the force of static friction Fs. Although it may appear that FS `

can be raised to any desired level by increasing the normal force Fn, there is an upper limit for Fn since the wire will be permanently deformed if Fn be raised to an unduly high level. Even should only resilient deformation of the wire occur an error in`rotation of rotary encoder 170 may be introd-uced as a result of the deformation of the cross-section of wire.
In order to feed a given amount of wire in a minimum amount of time, the acceleration of the feed roli 42 should be established at a max-imum practical acceleration level in the light of the friction and force considerations discussed above.
In a wire bundle to be produced by the steps illustrated in Figure 8A none of the ends of wire W6 - WlO of the bundle are aligned as they are in the bundle to be produced by the steps illustrated in Figure 8. According to Figure 8A the apparatus is programmed so that the wires are fed in seven ' separate feeding steps. One wire, the wire W7, is in alignment with, but is

2 spaced from, another wire, the wire W6, in the bundle.
It is an advantage of the apparatus that the wire is metered by~

. the feed roll 42. Although a separate rotary encoder for measuring the length of wire fed could be coupled to each pressure roll 58a to 58e or to each wire, the provision of a separate rotary encoder in respect of each wire 3Q would greatly increase the cost of the apparatus.
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Claims

THE EMBODIMENTS OF THE INVENTION FOR WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE AS FOLLOWS:

1. Wire feeding apparatus comprising a wire feed roll, a motor for driving the feed roll in rotation about its own axis, a plurality of pressure rolls each of which is rotatable about an axis which is parallel to that of the feed roll and control means for moving each of the pressure rolls between a wire feeding first position adjacent the feed roll and a non-wire-feeding second position remote from the feed roll, the control means being arranged selectively to move the pressure rolls between their first and second positions and to start and stop the motor to determine the lengths of wires to be fed in accordance with predetermined wire feeding programme.

2. Apparatus according to Claim 1, in which the control means comprises means for counting the number of revolutions performed by the feed roll and for controlling the motor in accordance with the count reached by the counting means.

3. Apparatus according to Claim 2, in which the control means comprises means for causing the feed roll to accelerate from rest at a substantially constant rate and then to decelerate at a substantially constant rate until the feed roll has stopped.

4. Apparatus according to Claim 1, 2 or 3, in which feed roll is run for predetermined periods to feed a plurality of the wires incrementally the wires being fed by the same length during each such period.

5. Apparatus according to Claim 1, in which each pressure roll is carried intermediate the ends of an arm pivoted on one side of the axis of rotation of the pressure roll, to a frame, and being connected on the other side of such axis to a piston-and-cylinder device actuable by the control means to displace the arm about its pivotal axis.

6. Apparatus according to Claim 5, in which the arm carries a clamping member on the side of the pivotal axis of the arm remote from the axis of rotation of the pressure roll, the clamping member serving to press a wire extending between the pressure roll and the feed roll, against a wire guide in the non-wire-feeding position of the pressure roll.

7. Apparatus according to Claim 5 or 6, in which each arm comprises two parallel portions receiving one of the pressure rolls between them, the arms being mounted on a common pivot shaft extending between two supporting plates and the frame, the feed roll also being mounted between these plates and being directly connected to the shaft of the motor.

8. Apparatus according to Claim 1, 2 or 3 comprising wire severing means positioned downstream of the feed roll and a device for applying a tie about the wires, positioned downstream of the wire severing means.

9. A method of feeding wire in accordance with a predetermined wire feeding programme, comprising the steps of; guiding a plurality of wires each from a wire source to position the leading ends of the wires on a driven wire feed roll with each wire positioned between the feed roll and a pressure roll individual to that wire and which is spaced therefrom;
selectively feeding the wires by moving the pressure roll associated with each wire to be fed, into feeding contact therewith and repeatedly starting and stopping the feed roll to determine the lengths of wire to be fed in accordance with the predetermined wire feeding programme.

10. A method according to Claim 9, in which the leading end of the wires are positioned on the feed roll in lateral alignment.

11. Wire feeding apparatus comprising: a wire feed roll having a width which is sufficient to receive a plurality of wires in side-by-side parallel relationship, a motor for rotating the feed roll, a plurality of pressure rolls mounted on axes which extend parallel to the axis of the feed roll, each of the pressure rolls having a non-feeding position, in which it is spaced from the feed roll, and being individually movable towards the feed roll a wire feeding position, wire guide means effective to guide wires from substantially end-less wire sources towards the feed roll and position one wire between the feed roll and each of the pressure rolls, and control means for starting and stopping the motor in accordance with a wire feeding programme and for moving the pressure rolls selectively individually or selectively in unison from the non-feeding positions to the wire feeding positions whereby, upon discriminative operation of the control means, the apparatus will produce groups of fed wires of varying predetermined lengths with the ends of each wire disposed at any desired location relative to the ends of the longest wire in the group.