GB2071004A

GB2071004A - Apparatus for use in attaching a plastics heel to a shoe

Info

Publication number: GB2071004A
Application number: GB8008221A
Authority: GB
Original assignee: British United Shoe Machinery Ltd
Current assignee: Noxet UK Ltd
Priority date: 1980-03-11
Filing date: 1980-03-11
Publication date: 1981-09-16
Also published as: GB2071004B

Abstract

Apparatus for use in attaching a plastics heel to a shoe by inserting a fastener F through the insole of the shoe into the heel. The fastener is pressed into the heel while being vibrated at an ultrasonic frequency by horn 16 so that the plastics material of the heel is melted or softened to allow the fastener to enter the heel and become embedded therein. The apparatus also comprises digital counter timing means operable to terminate a cooling period during which the fastener is pressed into the heel after insertion after a time which is in a selectable ratio to the insertion time. <IMAGE>

Description

SPECIFICATION Apparatus for use in attaching a plastics heel to a shoe This invention is concerned with apparatus for use in attaching a plastics heel to a shoe.

A recent development in the shoe industry has been apparatus for use in attaching a plastics heel to a shoe by inserting a fastener in the form of a broad-legged staple through an insole of the shoe into the heel. This apparatus comprises pressing means operable to press the fastener into the heel and vibrating means operable to cause a fastener being pressed by the pressing means to vibrate at an ultrasonic frequency so that plastics material of the heel is melted or softened allowing the fastener to enter the heel and become embedded therein. After the fastener has been inserted, it is necessary to hold the fastener in position while the plastics material solidifies and, hence, the pressing means is arranged to press the fastener into the heel for a cooling period after insertion of the fastener has been completed and the vibrating means has ceased operating.

It is necessary that the cooling period of the apparatus be long enough to ensure solidification of the plastics material but, in the interests of productivity, it should not be overprolonged as would often be the case if a fixed period, long enough to cover the longest solidification time, were used.

It is an object of the present invention to provide means whereby the time of the cooling' period is determined for each operation of the machine and automatically terminated after that time.

This object is achieved in that the apparatus also comprises timing means operable to terminate the cooling period by causing the pressing means to release the fastener after a time which is in a selectable ratio to the time taken to insert the fastener. This provides that the longer the heating takes, the longer is the cooling period and the correct ratio can be determined to give maximum productivity.

The invention provides apparatus for use in attaching a plastics heel to a shoe by inserting a fastener through an insole of the shoe into the heel, the apparatus comprising pressing means operable to press the fastener into the heel and vibrating means operable to cause a fastener being pressed by the pressing means to vibrate at an ultrasonic frequency so that plastics material of the heel is melted or softened allowing the fastener to enter the heel and become embedded therein, the pressing means being arranged to press the fastener into the heel for a cooling period after insertion of the fastener has been completed and the vibrating means has ceased operating, the apparatus also comprising timing means operable to terminate the cooling period by causing the pressing means to release the fastener after a time which is in a selectable ratio to the time taken to insert the fastener.

There now follows a detailed description, to be read with reference to the accompanying drawings of an apparatus-that is illustrative of the invention. It is to be understood that the illustrative apparatus has been selected for description by way of example.

In the drawings: Figure 1 is a side elevational view, partly in section, of the illustrative apparatus showing it operating on a shoe; and Figures 2A and 2B are diagrammatic views of portions of electrical timing means of the illustrative apparatus.

The illustrative apparatus is for use in attaching a plastics heel H (Fig. 1 ) to a shoe S by inserting a fastener F through an insole I of the shoe into the heel H. The apparatus comprises a stand 4 on which the shoe S and the heel H are supported with the heel H clamped in the desired position on the shoe S by two clamping members 10 and 12. The clamping members 10 and 12 are supported on an arm 14 which is movably vertically by a piston and cylinder assembly (not shown) to bring the members 10 and 12 into clamping engagement with the heel H. The fastener F is in the form of a broad-legged staple made from strip steel.

The stand 4 is hollow and contains a horn 16 which is movable vertically within the stand by the action of a piston and cylinder assembly (not shown) to pick up a fastener F contained in a recess 18 opening through the top of the stand 4 and press it into the heel H. This piston and cylinder assembly thus forms pressing means operable to press the fastener F into the heel H. The horn 16 is also connected to vibrating means (not shown), in the form of an ultrasonic transducer, operable to cause a fastener being pressed by the pressing means to vibrate at an ultrasonic frequency so that plastics material of the heel H is melted or softened allowing the fastener F to enter the heel H and become embedded therein.The pressing means is arranged when insertion of the fastener F begins, i.e. when the top of the fastener F comes into contact with the bottom of the heel H, to close a microswitch LS (Fig. 2A). The microswitch LS is closed when a pressure switch in the circuit of the pressing means operates. The pressing means is also arranged to press the fastener F into the heel H for a cooling period after insertion of the fastener F has been completed and the vibrating means has ceased operating. However, when the fastener F has been fully inserted, i.e. when the top of the horn 16 comes level with the top of the stand 4, the pressing means is arranged to open the microswitch LS.

The illustrative apparatus also comprises timing means operable to terminate the cooling period by causing the pressing means to move the horn 16 downwards to release the fastener F. The timing means comprises the electrical circuit shown in Figs. 2A and 2B and operates after a time which is in a selectable ratio to the time taken to insert the fastener F.

Figs. 2A and 2B show portions of the same circuit and together show the entire circuit except that power supply connections to the various components have been omitted in the interests of clarity. Various resistors, diodes and capacitors are shown in the circuit by conventional symbols therefor without being mentioned in the following description.

The circuit takes its power supply from a transformer T connected to an A.C. mains supply operating at 50 cycles per second.

From the transformer T, the power supply passes to an array of six rectifiers R which has four output lines L1, L2, L3 and L4. The rectifiers R provide electrical pulse generating means operable to generate a first sequence of pulses at 50 pulses per second to be used for determining the insertion time and a second sequence of pulses at 100 per second to be used for determining the cooling period.

The line L1 receives an output which is a fully rectified sine wave (i.e. the negative portion of each wave is rectified and the voltage is always positive) which therefore has 100 pulses per second. The line L2 receives an output which is half wave rectified (i.e. the negative portion of each wave is cut off) which therefore has 50 pulses per second.

The lines L1 and L2 pass through Schmidt inverters 11 which serve to sharpen the pulses. The line L3 is connected to an earth line which also has a terminal A connected thereto which has various connections which are not shown in the interests of clarity but which are indicated by an A in a circle. The line L4 is connected to a d.c. power line L5 and supplies power thereto.

The line L5 is connected via a resistor to a terminal B which is separated from the earth line by a Zener diode Z and a capacitor connected in parallel. Connections to the terminal B are indicated by a B in a circle in the interests of clarity. The line L5 is also connected to two relays RLA and RLB. The relay RLA, when de-energised, causes the pressing means to release the fastener F. The relay RLB, when energised, causes the pressing means to release the fastener F.

The line L1 crosses from the portion of the circuit shown in Fig. 2A to that portion shown in Fig. 2B where it is connected to a presetdivide-by-N-counter Cl. The counter C1 has five inputs on which it receives coded numbers between 0 and 8 from an array of resistors RA connected as shown in Fig. 2B.

The number received from the resistors being dependent on the position of a selector switch SS which is operable to connect various combinations of the resistors in the array RA to earth so that signals are only received by the counter C1 from the remaining resistors.

When the counter C1 receives a pulse on the line L1, it adds one to the coded number that it receives from the array RA until the total of pulses received and the coded number equals nine; whereupon the counter C1 provides a signal on an output thereof which is connected to a NAND gate N1 and no signal on an output thereof which is connected to the NAND gate N1 via an inverter 12. When this occurs, the NAND gate N1 receives a signal on both of its inputs and it causes an inverter 14 to pass a signal to a flip flop FF. The counter C1 also has an output which passes the pulses received on the line L1 through an inverter 13 to the flip flop FF. When the flip flop FF receives a signal from the inverter 14, it changes the signals on two output lines L6 and L7 thereof.The line L6 is connected to the counter C1 while the line L7 returns to the portion of the circuit shown in Fig. 2A. The signal on the line L6 is changed to a positive signal which is passed to the counter Cl and causes it to re-set itself to the number received from the array RA. The signal on the line L7 is reduced to zero and remains there until a pulse is received by the flip flop FF from the inverter 13 whereupon the signals on the lines L6 and L7 are restored to their previous values. It will, therefore, be apparent that the counter C1 operates the flip flop FF after receiving N pulses on the line L1 and the flip flop FF then sends a pulse down the line L7, where N is 9 minus the number received from the array RA.The selector switch SS is shown in Fig. 2B in a position corresponding to N equals 2 which makes the coded number 7 which is made up of the three lowermost resistors shown with the two uppermost resistors being connected to earth via the switch SS.

The selector switch is movable anticlockwise to set N successively as 1, 2, 3, 4, 5, 6, 7, 8 and 9. It will be seen that the portion of the circuit shown in Fig. 2B receives pulses at 100 per second on the line L1 and sends pulses at 100 divided by N to the portion of the circuit shown in Fig. 2A along line L7; where N is set by the position of the switch SS. Thus, the portion of the circuit shown in Fig. 2B provides adjustment means operable to adjust the frequency of pulses in the second sequence which reach the counters C2 and C3 to thereby vary the ratio of the cooling period to the insertion time. The line L7 is connected to an input of a NOR gate G1.

The aforementioned line L2 supplies pulses at 50 cycles per second to a NOR gate G2 (Fig. 2A) which has its other input connected to the microswitch LS through an inverter 15.

The microswitch is also connected. via the inverter 15 and a further inverter 16, to the remaining input of the NOR gate G1 and, along a line L8 to inputs of two pulse counters C2 and C3. When the microswitch LS is closed at the beginning of the insertion time of the apparatus, the signal from the inverter 15 to the gate G2 is removed so that the gate G2 passes the pulses it receives on the line L2 (50 per second) to its output which is connected to two pulse counters C2 and C3 which are connected together to form a single counter having eight outputs and therefore being capable of counting up to 255 pulses.

The counters C2 and C3, at this time, also receive a signal on the line L8 which causes them to total the pulses they receive whereas, if there is no signal on the line L8 the counters C2 and C3 act to subtract pulses from a total already reached.

The counters C2 and C3 also have inputs from the aforementioned NOR gate G1 and re-setting inputs from earth. The counter C2 has four outputs connected to an-eight-input NOR gate G3 one of these four outputs being connected to the eighth input of gate G3 which is also connected via the inverters 15 and 16 to the microswitch LS. The counter C2 has also an output connected to the counter C3 so that the counters are connected to form a single counter. The counter C3 has four outputs all connected to the NOR gate G3.

While the microswitch LS is closed (i.e. during the insertion time), the counters C2 and C3 count the pulses that reach it from the NOR gate G2 (50 pulses per second).

When the microswitch LS opens, i.e. at the end of the insertion time and the beginning of the cooling period, the gate G2 receives a signal from the inverter 15 and ceases passing pulses to the counters C2 and C3. Meanwhile, the signal on the line L8 has gone to zero so that the counters C2 and C3 begin to subtract pulses they receive from the total already counted. The counters C2 and C3 receive pulses from the gate G1 (100 divided by N per second) since the gate Go is now receiving no signal from the inverter 16 and passes pulses on the counters C2 and C3.

The NOR gate G3 receives, as already mentioned, eight inputs from the counters C2 and C3. The eighth input is also from the microswitch LS via the inverters 15 and 16. This eighth input has a signal thereon while the microswitch LS is closed so that the gate G3 does not produce a signal on its output during the insertion time. However, during the cooling period, the microswitch LS is open and the eighth input carries no signal from the inverters 15 and 16. Until the counters C2 and C3 have counted down to zero, their eight outputs to the gate G3 will have signals on them in various combinations but, when the counters C2 and C3 reach zero, the gate G3 receives no signal on all eight of its inputs and produces a signal on its output.

The output of the gate G3 is connected to the counter C2 and signals the counters C2 and C3 to stop counting down and hold the count at zero. The output is also connected via an inverter 18 to a Darlington driver D1 which is connected to the relay RLA. When the gate G3 produces a signal on its output, the Darlington driver loses its signal from the inverter 18 and de-energises the relay RLA causing the pressing means to release the fastener and thereby terminating the cooling period. Thus, the counters C2 and C3 provide counting means operable to count pulses from the first sequence of pulses during insertion of the fastener F and also further counting means operable to count pulses from the second sequence during the cooling period.

The relay RLA provides control means operable to cause the pressing means to release the fastener when the counts are equal which occurs when the counters C2 and C3 have a nil count.

Three of the outputs of the counter C3 are also connected to a three-input NAND gate N2 whose output is connected via an inverter 19 to a Darlington driver D2 connected to the relay RLB. This portion of the circuit provides safety means associated with the counters C2 and C3 and operable, if the count of pulses reaches a predetermined number, to cause the pressing means to release a fastener F. The three outputs of the counter C3 will all have a signal thereon when the counters C2 and C3 have counted 224 pulses during the insertion time corresponding to 4.48 seconds. Since this time is longer than should be taken to insert the fastener F, if this count is reached, it indicates that the apparatus is not operating correctly and the apparatus should be turned off by operation of the pressing means to allow investigation. Thus, when the NAND gate N2 receives a signal on all of its inputs it removes the signal from its output and the inverter 19 sends a signal to the Darlington driver D2 which energises the relay RL9.

It will be apparent that, at the end of the insertion time, the timing means terminates the cooling period after a time which is in a ratio to the insertion time which is set by the position of the switch SS. If the switch is set successively to give N equals 1, 2, 3, 4, 5, 6, 7, 8 and 9, the cooling periods will be respectively half, the same, one and half times, twice, two and half times, three times, three and a half times, four times, and four and a half times the insertion time.

Claims

1. Apparatus for use in attaching a plastics heel to a shoe by inserting a fastener through an insole of the shoe into the heel, the apparatus comprising pressing means operable to press the fastener into the heel and vibrating means operable to cause a fastener being pressed by the pressing means to vi brate at an ultrasonic frequency so that plastics material of the heel is melted or softened allowing the fastener to enter the heel and become embedded therein, the pressing means being arranged to press the fastener into the heel for a cooling period after insertion of the fastener has been completed and the vibrating means has ceased operating, the apparatus also comprising timing means operable to terminate the cooling period by causing the pressing means to release the fastener after a time which is in a selectable ratio to the time taken to insert the fastener.

2. Apparatus according to claim 1 wherein the timing means comprises electrical pulse generating means operable to generate a first sequence of pulses to be used for determining the insertion time and a second sequence of pulse to be used for determining the cooling period, counting means operable to count pulses from the first sequence during insertion of the fastener, further counting means operable to count pulses from the second sequence during the cooling period and control means operable to cause the pressing means to release the fastener when the counts of the counting means and the further counting means are equal.

3. Apparatus according to claim 2 wherein the first and the second counting means are combined in a single counter operable to total pulses during insertion of a fastener and subtract pulses from the total reached during insertion during the cooling period, the control means being arranged to operate when the counter has a nil count.

4. Apparatus according to either one of claims 2 and 3 wherein the electrical pulse generating means comprises adjustment means operable to adjust the frequency of pulses in the second sequence of pulses which reach the further counting means to thereby vary the ratio of the cooling period to the insertion time.

5. Apparatus according to claim 4 wherein the adjustment means comprises a pre-settable-divide-by-N-counter in which N is set supplying a coded number to the counter.

6. Apparatus according to claim 5 wherein the pre-settable-divide-by-N-counter has an array of resistors associated therewith, various combinations of which resistors can be selectively connected in circuit to apply various coded numbers to the counter to set N.

7. Apparatus according to any one of claims 1. 2. 3. 4. 5 and 6 wherein the cooling period can be selectively set at a half, the same, one and a half times, twice, two and a half times, three times, three and a half times. four times, or four and a half times the insertion time.

8. Apparatus according to any one of claims 2. 3, 4. 5, 6 and 7 wherein safety means are associated with the first counting means. which safety means are operable, if the count of the first counting means reaches a predetermined number, to cause the pressing means to release the fastener.

9. Apparatus for use in attaching a plastics heel to a shoe substantially as hereinbefore described with reference to and as shown in the accompanying drawings.