GB2343135A

GB2343135A - Method and apparatus for control of a pneumatic press and a pneumatic press

Info

Publication number: GB2343135A
Application number: GB9823621A
Authority: GB
Inventors: William George Ryrie Dempster
Original assignee: Ethicon Ltd
Current assignee: Johnson and Johnson Medical Ltd
Priority date: 1998-10-28
Filing date: 1998-10-28
Publication date: 2000-05-03
Anticipated expiration: 2018-10-28
Also published as: GB2343135B; GB2373469B; GB2373469A; GB9823621D0; GB0207115D0

Abstract

A method and apparatus for control of a pneumatic press and a pneumatic press assembly in which the number of strokes of the press, the pressure of the first stroke and the pressure of the final stroke are set. The method and apparatus providing a stepped up pressure. The assembly includes a means for rotating the item being pressed in relation to the press. The control means may comprise electro pneumatic regulator 40 and two solenoid makes 42 attached to air cylinder 8 of the pneumatic press.

Description

Method and Apparatus for Control of a Pneumatic Press and a Pneumatic Press The present invention relates to a method and apparatus for control of a pneumatic press and a pneumatic press, particularly for use in automatic needle-suture assembly.

It has long been known in the surgical art to secure a suture within a barrel end of a surgical needle by the method of swaging. In this method, one end of the suture is inserted into an axial end opening of the needle barrel and this end of the needle is then compressed to grip the suture. The compression is known to be carried out by a pneumatic press.

Stainless steel needles are known to be made of hard grade steel such as 4310 grade stainless steel. The stainless steel needle is drilled and various suture materials or threads are inserted into the drilled portion of the needle. 4310 grade steel is hard and when applying the necessary force to swage the needle and thread, the needle may"crack".

It is an object of the present invention to provide a method and apparatus for control of a pneumatic press capable of stepping up the pressure progressively. In the case of a surgical needle, the risk of cracking of the needle is thereby reduced.

The method and apparatus for control of a pneumatic press is suitable for use with any new pneumatic press where stepped up pressure is required.

According to a first aspect of the present invention, there is provided a method for control of a pneumatic press comprising: (a) setting the number of strokes of the press; (b) setting the pressure of the first stroke of the press ; and (c) setting the pressure of the final stroke of the press. Preferably, the method includes setting the frequency or speed of the strokes of the press. Preferably, the method includes setting the pulse width, duration or dwell of the strokes of the press.

Preferably, the pressure of the strokes is increased by equal increments between the pressure of the first stroke and the pressure of the final stroke.

Preferably, the settings of the pressure for of the first and final strokes of the press can be determined in relation to the thickness of the item being pressed.

The method of control for pneumatic press may be for swaging a needle-suture assembly.

Preferably, the method includes setting the range of rotation of the press between the strokes of the press. Preferably, the range of rotation can be increased in increments of 10 .

According to a second aspect of the present invention, there is provided a control apparatus for a pneumatic press comprising: (a) means for controlling the number of strokes of the press; (b) means for setting the pressure of a first stroke of the press; and (c) means for setting the pressure of the final stroke of the press.

Preferably, the control apparatus includes means for controlling the frequency of the strokes.

Preferably, the control apparatus includes means for setting the pulse width, duration of contact time or dwell of the dies of the pneumatic press. Preferably, the control apparatus includes means for increasing the pressure of the strokes by equal increments between the pressure of the first stroke and the pressure of the final stroke.

The control apparatus may control a needle-suture swaging press.

Preferably, the control apparatus includes means for setting the range of rotation of the press between strokes of the press. The means for setting the range of rotation may be increased by increments of 10 .

The control apparatus may include a potentiometer for controlling the frequency and pulse width of the strokes, an electro pneumatic regulator for increasing the pressure of the strokes and a stepper motor for setting the range of rotation of the press.

The control apparatus may include a monitoring means for monitoring the operation of the apparatus. The monitoring means may be a binocular microscope. Alternatively, the monitoring means may be closed-circuit television.

According to a third aspect of the present invention, there is provided a pneumatic press comprising an air cylinder, a pair of dies and a support means for supporting an item to which pressure is to be applied, wherein the press includes a means for rotation of the support means in relation to the air cylinder.

Preferably, the pneumatic press is a needle-suture swaging press.

Preferably, the rotation means can be arranged to rotate through a given angle between strokes of the air cylinder.

The pneumatic press may include a monitoring means for monitoring the operation of the press. The monitoring means may be a binocular microscope for a manned press. Altematively, the monitoring means may be closed-circuit television for an unmanned press.

Embodiments of the present invention will now be described, by means of example only, with reference to the accompanying drawings in which: Figure 1 is a diagrammatic representation of the apparatus for control of a pneumatic press and a pneumatic press in accordance with the present invention; Figure 2 is a front view of a control box for use with the method and control apparatus in accordance with the first and second aspects of the present invention; Figure 3 is a rear view of the control box of Figure 1; Figure 4 is a pneumatic press in accordance with the third aspect of the present invention and suitable for being controlled by the method and control apparatus in accordance with the first and second aspects of present invention, the press being for swaging a needle-suture assembly ; Figure 5 is a detail of the front view of Figure 3; Figure 6 is a detail of a back view of the pneumatic press of Figure 3; Figure 7 is a side elevation of the detail of Figure 5; Figure 8 is a side elevation of the detail of Figure 5; Figure 9 is an end elevation of the detail of Figure 5; Figure 10a is a side elevation of a needle support arm for a pneumatic press in accordance with the third aspect of the present invention; Figure 10b is a cross-section through line Y-Y of Figure 10a ; Figure 10c is a cross-section through line X-X of Figure 10a; Figure 11 a is a top elevation of the needle support arm of Figure 10a; and Figure 11 b is a view on'A'of Figure 11 a.

The present invention relates to a method and apparatus for control of a pneumatic press and a pneumatic press. Embodiments of the present invention are now described with reference to a pneumatic press for swaging a needlesuture assembly.

The method and apparatus for control of a pneumatic press can be used for attaching drilled surgical needles, for example formed of stainless steel of 4310 grade, to various suture materials (threads). 4310 grade steel is hard and when applying the necessary force to swage the needle and thread, the needle can "crack". A means of enabling the pneumatic press to give"stepped up pressure"for progressive swaging of needle suture is required.

Figure 1 shows an apparatus for control of a pneumatic press with a control box 46 for control of an electro pneumatic regulator 40 and two solenoid valves 42 attached to an air cylinger 8 of a pneumatic press. Operation of the control box 46 is by means of a foot pedal 44. Figures 2 and 3 show an embodiment of the control box 46 for controlling the pressure of a pneumatic press. The control box 46 has 5 variables: (a) Number of strokes of the press set from 1 to 9 for each action of a foot pedal ; (b) The air pressure setting for a first stroke of the press; (c) The air pressure setting for a final stroke of the press; (d) The frequency (speed) of strokes of the press; (e) The pulse width (dwell) contact time of swaging dies of the press during each stroke.

The electro pneumatic regulator 40 varies the pressure of the cylinder 8. This is achieved by varying the voltage which increases the size of an orifice which in turn increases the air flow. The voltage is raised by a potentiometer (dials 106, 108). Electro pneumatic regulators are well known, for example IT200 of SMC Corporation.

In an example with four strokes or hits of a pneumatic press, the first hit can be set at 20 PSI and the final hit can be set at 50 PSI. Automatically, the second hit would be 30 PSI and the third hit would be 40 PSI. The operator can rotate the needle through 90 between each stroke of the press.

An embodiment is also provided in which the press rotates. Instead of an operator rotating the needle, the press rotates the needle with the operator holding the needle stationary. A stepper motor 10 controls the rotation of the press.

The control apparatus has been designed to give equally stepped up pressure for a pre-set number of strokes of an air cylinder 8 of the pneumatic press. To allow the press to operate quickly two solenoid valves 42 are fitted to each side of the cylinder 8 for quick switching and quick exhausting.

Referring to Figures 2 and 3, the'N'switch 100 sets the number of strokes of the cylinder 8 for one hit of the foot pedal 44. The'FQ'pot 102 sets the frequency of strokes of the cylinder 8. The'PW'pot 104 sets the dwell time of the dies. The Zero'Z'pot 106 sets the air pressure of the first hit. The Gain'G' pot 108 sets the air pressure of the final hit with every hit in between, increasing by equal increments. The'A-M'switch 110 is for automatic or manual. In the automatic mode the cylinder 8 will stroke and dwell repeatedly at the set frequency. The manual switch can be used in conjunction with the'N'switch 100 predetermining the number of strokes of the cylinder 8 for one press of the foot pedal 44.

An example starting point for the dials are: N Switch = 4 FQ pot 1. 0 PWPot = 7. 6 With the Z pot 106 initially set at 0.0 and the G pot 108 initially set at 0.0, the G pot value 108 can be increased until the dies are touching on the last stroke of the cylinder 8. With a needle between dies, the Z pot 106 can be increased until the top die is in contact with the needle on the first stroke of the cylinder 8.

Depending on the wall thickness of the needle the Zero'Z'and Gain'G'settings will vary.

For example: 'Z'set at 2.0 'G'set at 4.0 If when the press is set up and after initial attachments the pull values are too low but the quality of swage is good, the pull values can be improved by increasing the Z and the G dials 106,108. In effect this increases the air pressure. If the attachments are too strong the pressure can be reduced by decreasing the values of the Z and G dials 106,108.

If, when the press has been set up, the pull values were good but the quality of swage could be improved, this can be achieved by increasing the number of hits and reducing the pulse width PW dial 104. If it is desired to increase the number of hits it would be necessary to either increase the range, or reduce the speed or frequency dial FQ 102.

In an embodiment in which the press can rotate between hits or strokes, a further control is provided for setting the range of rotation of the press.

The following is an explanation of the controls : RANGE-This is the angle the press rotates between the first and last swage, it can be increased in 10 degree increments by stepping up the range control by 1.

O setting = 90 degree rotation 1 setting = 100 degree rotation 2 setting 110 degree rotation 3 setting = 120 degree rotation 4 setting = 130 degree rotation 5 setting = 140 degree rotation 6 setting = 150 degree rotation 7 setting = 160 degree rotation 8 setting = 170 degree rotation 9 setting = 180 degree rotation.

HITS-This button sets the amount of swages the press will have for one press of the foot pedal 44. This could be anything between 1 and 99. To achieve 99 hits the speed would have to be greatly reduced. Similarly the pulse width. For example, 1.5 speed (FQ 102), 0.2 pulse width (PW 104), range 9,3 on the Zero (Z 106) and 4 on the Gain (G 108).

SPEED-This dial 102 determines the cycle time the press takes, i. e.

10 is the maximum speed 0 is the minimum speed The cycle time is the forward movement of the press, on the return movement the press does not attach. The operator can be preparing another needle and suture on the return stroke.

PULSE WIDTH-This dial 104 determines the contact time of the attaching dies.

For example, if the pulse width is set at 3.0 there will be a longer contact than if it was set at 1.0. The shorter the contact the more hits can be made when rotating the press.

ZERO AND GAIN DIALS-These are the dials 106,108 which allow progressive swaging of the press. With the press set up with a pre-determined amount of hits, the Z dial 106 sets the air pressure for the first hit, the G dial 108 sets the pressure for the final hit.

The first hit is softer than the final hit and each hit in between steps up equally in pressure.

Care should be taken when adjusting dies to ensure that the centre of the die groove form rotates on the centre of the guide rail 6. A gauge can assist with this setting by fitting the guide to the rail with the rotating arm in the, for example, 180 position of stroke, and extending the tip of the pointer to meet the die groove.

When equipment is first powered up after being out of use, the rotating die assembly may have rotated under its own weight to some position away from the start point, it would be desirable in this case to ensure that the die assembly is manually rotated to the start position before the power is switched on.

The control unit 46 is made to operate from a 240V AC 13 amp supply and can be connected direct to any pneumatic line of approximately 40-1001b/sq. in. pressure. No other line pressure regulation is necessary.

A rotary manual swager for control by the control method and apparatus of the present invention can be controlled by four potentiometers and two digital counters on the front panel of the electrical cabinet.

Examples Summary of Controts Hits-the press can be set to give a maximum of 99 hits.

Range-press can rotate in increments of 10 from setting 0 = 90 to setting = 180 .

Speed-the cycle time i. e. from first to last hit can be increased or decreased (return cycle being non-functional).

Pulse width-the contact dwell of dies can be increased or decreased.

Zero-is the air pressure setting for 1 st stroke of the cylinder only.

Gain-is the air pressure setting for last stroke of the cylinder only.

Ideal Start Setting Hits 5, range 0, speed 10, pulse width, 2.5 zero 6.3, gain 8.3.

Examples of Settings Require 12 hits at 120 rotation. a. Set hits at 12. b. Set range at 3. c. Reduce speed to 8. d. Reduce pulse width to 1.0.

Require 99 hits at 180 rotation. a. Set hits at 99. b. Set range at 9. c. Reduce speed to 3. d. Reduce pulse width to 0.5.

Require 65 hits at 100 rotation. a. Set hits at 65. b. Set range at 1. c. Reduce speed to 3. d. Reduce pulse width to 0.5.

Require 4 hits at 90 rotation. a. Set hits at 4. b. Set range at 0. c. Re set speed at 10. d. Set pulse width at 3.

Advantages of the control apparatus of the present invention are as follows : (a) The control unit 46 s small and suitable for any pneumatically operated press.

(b) No finger guards are required because of the reduced gap between dies.

(c) The press operates more quietly due to the electronic controls plus small stroke.

(d) The speed in which the press operates can be increased or decreased making the press ideal for training new operators.

(e) The force in each stroke of the cylinder 8 can be increased or decreased making the press suitable for all the drilled needles.

The needle pull valves are in excess of the equivalent pull values for channel needles.

(g) One press of the foot pedal 44 is all that is required to give the operator a maximum of 9 strokes of the cylinder.

(h) Less maintenance required to the press due to fewer moving parts.

Referring to Figures 3 to 8, a needle-suture swaging assembly 1 is shown including a pneumatic press which can be controlled for progressive stepped up increase in pressure. The assembly 1 includes a rotation means for rotating the pneumatic press between strokes of the press.

A stepper motor 10 controls the rotation of the press and is connected via a timing pulley 14 and timing belt 50. By selecting a pre-determined setting i. e. frequency, pulse width, number of hits, Zero and Gain, one press of the foot pedal 44 rotates the press and strokes the cylinder 8. The press will automatically return to the start position.

The assembly 1 has a carriage 4 and a slide ring 6 relative to which a carriage 4 is moveable. The carriage 4 stides on the slide ring 6 between concentric journals 18 and eccentric joumals 20 with cam followers 22.

An air cylinder 8 is provided on the carriage 4 and is supported by a cylinder bracket 16. The carriage 4 also supports a stepper motor 10 with a motor bracket 12. The stepper motor 10 is provided with a timing pulley 14.

The air cylinder 8 has a cylinder bobbin 24. Figure 7 shows the right-hand tool slide 26, the left-hand tool slide 28 and an upper tool holder 30 and a lower tool holder 32 with a tool holder cover 34. Figure 8 shows the material guide 36 and attaching dies 38.

The air cylinder 8 can include a proximity sensor for detecting the starting position.

The tool holder arrangement can have an adjacent needle support arm 52, hand rest and hand pillar for supporting the needle to be swaged. Figures 11 and 12 show a needle support arm 52 which can assist when presenting the needle to the suture. The press can be used without such a needle support arm 52. The needle support arm 52 is fixedly attached to one end 54 of the slide ring 6.

The assembly 1 can be used manually with an attendant operator. The operator can view the operation of the pressing by the assembly 1 through a binocular microscope, in particular in the case of needles being swaged the needle pressing can be monitored though the microscope. In the case of an automatic use of the assembly, a camera can be directed at the press to monitor the operation by means of closed-circuit television.

Modifications and improvements can be made to the foregoing without departing from the scope of the present invention.

Claims

CLAIMS 1. A method for control of a pneumatic press comprising: (a) setting the number of strokes of the press; (b) setting the pressure of the first stroke of the press ; and (c) setting the pressure of the final stroke of the press.
2. A method for control as claimed in claim 1 wherein the method includes setting the frequency or speed of the strokes of the press.
3. A method for control as claimed in claim 1 or claim 2 wherein the method includes setting the pulse width, duration or dwell of the strokes of the press.
4. A method for control as claimed in any of claims 1 to 3 wherein the pressure of the strokes is increased by equal increments between the pressure of the first stroke and the pressure of the final stroke.
5. A method for control as claimed in any of the preceding claims wherein the settings of the pressure for of the first and final strokes of the press can be determined in relation to the thickness of the item being pressed.
6. A method for control as claimed in any of the preceding claims wherein the method is for a swaging a needle-suture assembly.
7. A method for control as claimed in any of the preceding claims wherein the method includes setting the range of rotation of the press between the strokes of the press.
8. A method for control as claimed in claim 7 wherein the range of rotation can be increased in increments of 10 .
9. A control apparatus for a pneumatic press comprising: (a) means for controlling the number of strokes of the press; (b) means for setting the pressure of a first stroke of the press; and (c) means for setting the pressure of the final stroke of the press.
10. A control apparatus as claimed in claim 9 wherein the control apparatus includes means for controlling the frequency of the strokes.
11. A control apparatus as claimed in claim 9 or claim 10 wherein the control apparatus includes means for setting the pulse width, duration of contact time or dwell of the dies of the pneumatic press.
12. A control apparatus as claimed in claim 9,10 or 11 wherein the control apparatus includes means for increasing the pressure of the strokes by equal increments between the pressure of the first stroke and the pressure of the final stroke.
13. A control apparatus as claimed in any of claims 9 to 12 wherein the control apparatus controls a needle-suture swaging press.
14. A control apparatus as claimed in any of claims 9 to 13 wherein the control apparatus includes means for setting the range of rotation of the press between strokes of the press.
15. A control apparatus as claimed in claim 14 wherein the means for setting the range of rotation may be increased by increments of 10 .
16. A control apparatus as claimed in any of claims 9 to 15, wherein the control apparatus includes a potentiometer for controlling the frequency and pulse width of the strokes.
17. A control apparatus as claimed in any of claims 9 to 16, wherein the control apparatus includes an electro pneumatic regulator for increasing the pressure of the strokes.
18. A control apparatus as claimed in claim 14 or 15, wherein the control apparatus includes a stepper motor for setting the range of rotation of the press.
19. A control apparatus as claimed in any of the preceding claims, wherein the apparatus includes a monitoring means for monitoring the operation of the apparatus.
20. A control apparatus as claimed in claim 19, wherein the monitoring means is a binocular microscope.
21. A control apparatus as claimed in claim 19, wherein the monitoring means is closed-circuit television.
22. A pneumatic press comprising an air cylinder, a pair of dies and a support means for supporting an item to which pressure is to be applied, wherein the press includes a means for rotation of the support means in relation to the air cylinder.
23. A pneumatic press as claimed in claim 22, wherein the pneumatic press is a needle-suture swaging press.
24. A pneumatic press as claimed in claim 22 or claim 23, wherein the rotation means can be arranged to rotate through a given angle between strokes of the air cylinder.
25. A pneumatic press as claimed in claim 22,23 or 24, wherein a support arm is provided on a slide ring moveable in relation to the air cylinder.
26. A pneumatic press as claimed in any of claims 22 to 25, wherein monitoring means is provided for monitoring the operation of the press.
27. A pneumatic press as claimed in claim 26, wherein the monitoring means is a binocular microscope.
28. A pneumatic press as claimed in claim 26, wherein the monitoring means is closed-circuit television.
29. A method for control substantially as hereinbefore described with reference to the accompanying drawings.
30. A control apparatus substantially as hereinbefore described with reference to the accompanying drawings.
31. A pneumatic press substantially as hereinbefore described with reference to the accompanying drawings.