US3451443A - Machines for manufacturing spring interiors - Google Patents

Description

June 24, 1969 w. SPUHL 3,451,443

MACHINES FOR MANUFACTURING SPRING INTERIORS Filed March 5, 1967 United States Patent US. Cl. Mil-92.7 4 Claims ABSTRACT OF THE DISCLOSURE A machine for manufacturing spring interiors and having a coiling device for forming a Wire into a spiral and screwing this spiral through juxtaposed end convolutions of rows of adjacent coil springs to connect them together is provided with a safety circuit in the form of a feed responsive monitor for automatically switching off the coiling device if the wire feed is obstructed.

The present invention relates to safety devices and more particularly to safety manufacturing spring interiors.

Machines for manufacturing spring interiors are known in which rows of coil springs whose end convolutions are connected together by wire spirals and a coiling device driven by a motor forms a wire into a spiral and screws this spiral through a series of pairs of tongs in each of which is located a pair of end convolutions of the coil springs, and wherein a cut-out is provided in order to switch the motor on and off in synchronism with the machine. It is very dilficult to increase the operating speed of these kinds of machines if the forming of the spiral is not accomplished in the manner provided for. It sometimes happens that the wire spiral in the process of being formed, strikes against an obstacle, particularly against one of the tongs, which at high operating speeds results in the defiagration of the wire in the coiling device, as will be described in more detail. Further, the spiral'b'eing formed may be deflected in some manner without the customary stopping device for the motor being actuated, so that the forming of the spiral continues unchecked. In both these cases the motor of the coiling device was hitherto stopped by the machine operator. The faster the machine operates, the more difficult it is to stop the motor rapidly enough to prevent greater damage. The present invention provides a safety device which prevents damage at least in the first-mentioned, relatively frequent case, and also in the second, very infrequent case.

According to the present invention a machine for manufacturing spring interiors is provided with a coiling device for forming a wire into a spiral and for screwing this spiral through a juxtaposed end convolutions of coil springs, arranged in adjacent rows, to connect the coil springs together, with a driving motor for the coiling device, a cutout switch for the motor being operable in synchronism with the operation of the machine and with a safety device comprising a monitor responsive to the feed of the coiling device for automatically switching off the motor if the wire feed is obstructed as a consequence of the wire spiral, being formed, striking against an obstacle.

The circuit preferably has a delayed-release relay whose time lag exceeds the normal time for forming a spiral, and which switches off the motor if the normal stopping device for the motor should fail at the end of the spiralforming period.

The invention will be further described by Way of eX- ample with reference to the accompanying drawing which shows in the sole figure thereof a circuit diagram of one devices for machines for embodiment of a safety device according to the present invention.

With reference to the accompanying figure, a machine for manufacturing spring interiors has a row of pairs of tongs Z Z Z serving to join together in pairs the end convolutions 1 of coil springs introduced into the machine in rows. A coiling device 2 serves to draw a wire 3 from a storage roll (not shown) and form it into a spiral 4 which is secured through the closed pairs of tongs Z Z joining together the pairs of end convolutions located in the said pairs of tongs. The coiling device 2 is driven by a motor M which is switched on by a switch S and switched off by a switch S The switch S is automatically closed in synchronism with the machine when the spring interior being manufactured is pushed forward and the end convolutions 1 of a new row of springs are laid in the pairs of tongs Z Z when two rows of springs have been joined together and the spiral 4 cut off by a cutting device 5. The switch S is opened, by a senser 6 arranged immediately in front of the final clamp Z each time the tip of the forwardly screwing spiral 4 strikes the senser 6. As a consequence of the lag of the motor 4 of the coiling device 2, a further short length of spiral is formed which is sufficient to join together the end convolution located in the pair of tongs Z In a machine of this kind it sometimes occurs that the spiral 4, is not conducted accurately through all the pairs of tongs Z Z but strikes against one of the tongs as a consequence of an irregularity in the wire 3, or for some accidental reason. This causes the spiral thus formed to become distorted and the wire in the coiling device 2 to jam between its feed rollers 7, causing a shrill noise. Hitherto, the machine operator had to stop the m0- tor by hand immediately, in order to prevent damage.

The faster the machine operates, the more difiicult it is to stop the motor M sufliciently rapidly to prevent the heat caused by the friction of the wire on the rollers 7 from burning out the wire and rendering it completely unserviceable. The portions of the spiral located in the tongs have to be screwed out of the tongs by hand, and the coiling device partly dismattled in order to put it into action again and resume normal operations. If it is desired to increase the productivity of the machine by employing two operators for laying in the springs, or if a fully automatic spring feed is provided, it is virtually impossible to stop the motor in time to prevent the abovementioned defiagration of the wire, if the spiral strikes against an obstacle, quite apart from the fact that an operator would have to supervise the machine purely for this purpose if an automatic spring feed were used.

Another fault which may occur in machines of this kind is that the spiral may be deformed and deflected to such an extent, by striking against a pair of tongs, that it does not jam, but by-passes the tongs and continues to be formed in space. A fault of this kind is not made perceptible by a shrill noise, so that if the operator does not stop the motor immediately as the fault occurs, the growing spiral can be caught in the machine rods and cause extensive damage and even accidents.

The safety device described hereinafter substantially eliminates the above-mentioned disadvantages,

A cut-out W is provided for switching the motor M on and off, the coil 8 of the cut-out W being energized when switch S closes, thus closing a three-pole switch 9 provided on the cut-out W and connecting the motor M to a three-phase power supply R, S, T. An alternating voltage connected between terminals 10 and 11 serves to energize the coil 8. The cut-out W has three contacts W W2, W3. When the switch 9 is open, the contact W1 is open and the contacts W2 and W3 are closed. The contact w has one side connected to the coil 8 and the switch S and the other side to the switch S The switch S is connected to a first contact 11 of a main relay H. A second contact h of the main relay H is connected between the contact W3 and the coil of a relay R A third contact h of the main relay H is connected between the contact W2 and the coil of a relay R The contacts h h and I1 are open when the main relay H is non-energized. The relays R and R each have only one respective contact r and r which are connected in series between two leads 12 and 13.

The lead 12 is connected to the main relay H and to one side of a push-button switch D serving to put the machine into operation, The lead 13 is connected to the contact I1 the other side of the push-button switch D, and the switch S The coils of relays R R and H are connected to a lead 14. The relays R and R are delayedrelease relays, the release lag of relay R being approximately 0.5 second, and the release lag of relay R being about seconds.

A speed monitor 15 has a contact K connected in parallel with the contact W3. The speed monitor 15 is preferably of the kind sold by the General Electricity Company under the model designation Al-Ni 5. The input shaft of the speed monitor 15 is coupled to a driver or carrier roller 16 on which the wire 3 runs before it enters the coiling device 2 and against which it is urged by two pressures rollers 17 and 18. If the wire 3 is conducted through the coiling device 2 at normal speed, the speed of rotation of the input shaft of the speed monitor is determined by the carrier roller 16, and the contact K is closed. The contact K is opened immediately the wire 3 stops as a consequence of the spiral 4 striking against one of the pairs of tongs Z Z A switch 19, operable only manually, is connected in parallel with the switch 9 of the cut-out W, to reverse the direction of energization for making the motor M run in a reverse direction, a conventional locking device being provided to prevent the switches 9 and 19 from closing simultaneously.

The safety device described operates as follows. When the machine is to be operated, the push-button switch D is temporarily closed, whereby the coil of the main relay H in the circuit 11, D, 12, H, 14, is energized and closes its contacts h h Consequently, the relay R in the circuit 11, W3, h R 14, 10 and the relay R in the circuit 11, W2, R 14, 10, are energized. When the pushbutton switch D is re-opened, the relay H remains energized via the closed contacts r and r in the circuit 11, 13, r r H, 14, 10.

When the switch S is temporarily closed in synchronism with the machine, the coil 8 in the circuit 10, 8, S 11 is energized, and the motor M is consequently set into motion via the switch 9. Since the coiling device 2 is now operating, the wire 3 conducted thereby, between the rollers 16, 17 and 18 actuates the speed monitor and closes its contact K, which contact K by-passes the contact W3 which has been opened by the response of the cut-out W. When the contact W3 opens the relay R remains in its energized state due to its release lag time of 0.5 second. It is then held in its energized state by the closed contact K. When the contact w opens, the relay R remains in its energized state due to its release lag time of about 5 seconds.

After the switch S has re-opened, the coil 8 remains energized by a holding current circuit 10, 8, W S I1 11 and the motor M remains switched on. The circuit is interrupted only when the tip of the spiral 4 reaches the senser 6, thus opening the switch S which has the effect of opening the switch 9 and stopping the motor M. The contact K of the speed monitor now opens, but, since the contact W is now closed again, the relay R is not deenergized. Similarly, the energizing circuit of the relay R is again closed by the contact W The relay R is not de-energized, since its time lag of about 5 seconds exceeds the approximate time of 4 seconds required to complete the forming of the spiral 4. The main relay H also remains energized, so that none of the relays H, R and R are de-energized during faultless operating cycle of the machine which is repeated when the switch S is closed again.

When the tip of the spiral strikes against one of the pairs of tongs, and the speed monitor 15 responds to the stopping of the spiral 4, the contact k opens, the circuit of the relay R is broken and the relay R is de-energized after approximately 0.5 second. When the switch r opens, the holding current circuit of the main relay H is broken, the main relay H is de-energized and, when its switch 11 opens, the holding current circuit of the coil 8 is broken. The switch 9 of the cut-out W thereby opens and the motor M is stopped. This stopping of the motor M is effected in a considerably more rapid manner than would be possible by the most attentive operator. The deflagration of the wire in the coiling device 2 is obviated, and it is necessary only to reverse the motor slightly by the hand-switch 14 and to cut off the deformed end of the spiral, before putting the machine into normal operation again by pressing the push-button switch D.

If the spiral 4 should deviate from the pairs of tongs, the relay R becomes effective by becoming deenergized approximately 1 second after the instant at which the spiral should have reached the final pair of tongs, thus de-energizing the main relay H, and so causing the motor M to stop again.

The safety device described allows the present operating speed of the machine to be increased by approxi mately 50%, without this value representing the upper limit set by the safety device.

Details of the safety device described may be altered without their efficiency being impaired. For example, if the circuit were altered accordingly, a speed monitor 15 could be used whose contact K would be closed when the wire 4 stops, or a terminal switch S could be used which would open in its normal position.

It is also to be noted that, in the safety device described, the motor M is also automatically switched off when the supply of the wire 3 is exhausted, since the speed monitor 15 opens its'contact K when it is not in operation.

I claim:

1. In a machine for manufacturing spring interiors from a plurality of coil springs, said machine having at least one row of pairs of tongs for holding together adjacent end convolutions of rows of coil springs; a coiling device for forming a wire into a spiral and for screwing said spiral through said tongs and said end convolutions held therein to connect the coil springs together; a driving motor for driving said coiling device; a cut-out switch for said motor, said cut-out switch being operable in synchronism with said machine; and a safety device comprising monitoring means responsive to the feed of wire to said winding device for switching off said motor if the wire feed is obstructed as a consequence of the wire spiral striking against an obstacle, said monitoring means including a main relay, a starting switch for energizing said main relay, a holding circuit for holding said main relay energized, a holding relay having a short delayed release, said holding relay having a contact in said holding circuit, a operating circuit for said holding relay, said operating circuit including a contact of said main relay and a contact of said cut-out switch, said holding relay being energizable when said main relay is energized, said monitoring means including a contact which is opened in response to obstruction of the wire feed, said cut-out switch contact being opened when said cut-out switch is energized to energize said motor and being connected in parallel with said contact of said monitoring means, a starting switch operable in synchronism with the machine for energizing said cut-out switch, and a holding circuit for said cut-out switch, said last-mentioned holding circuit including a normally open contact of said main relay.

2. A machine according to claim 1 which further comprises limit switch means at the end of said row of tongs, said limit switch means being normally closed and being opened when said wire spiral reaches the last pair of tongs in said row, said limit switch means being connected in said holding circuit of said cut-out switch for switching off said motor when the coil springs have been interconnected.

3. A machine according to claim 1 wherein said delayed release relay has a time lag which exceeds the time required for said coiling device to form a wire spiral and to feed said wire spiral through said tongs and said coil spring end convolutions held therein, said delayed release relay serving to stop said motor if said motor has not stopped at the end of said spiral forming operation.

4. A machine according to claim 1 which comprises a second holding relay having a normally open contact in said holding circuit of said main relay, said second holding relay having a comparatively long delayed release,

and an operating circuit for said second holding relay, said operating circuit including a normally open contact of said main relay and a normally closed contact of said cut-out switch.

References Cited UNITED STATES PATENTS CHARLES W. LAN'HAM, Primary Examiner. 15 E. M. COMBS, Assistant Examiner.

US. Cl. X.R.

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