EP0745459A1 - Pressurised fluid driven pliers - Google Patents

Abstract

The tongs have a switching rod movable in a guide(49) in the direction of the actuating piston and pretensioned by a spring(55) towards the valve spindle(61). The switching rod has a dog(53), and one actuating piston(42) has a stop(54) for carrying along the switching rod in the last part of its motion for closing the tongs' insert halves. The valve spindle has a locking seat(62) in which engages the switching rod by spring action when the valve spindle is moving from the neutral to the working position and releases the switching rod when it is being carried along by the actuating piston.

Description

The invention relates to a pressure medium pliers for clamping rings and the like. According to the preamble of claim 1.

A pressure medium pliers is known from DE-GM 87 16 694. With these pliers, actuation of the pressure medium valve causes the pistons to be pressurized with compressed air and to pivot the pliers insert halves by means of the wedge-shaped feed member. When the trigger is released, the pistons are aerated so that they are moved back into their starting position by a return spring. As a result, if the trigger is released prematurely from the pliers halves, the minimum closing gap required to securely close the Clamping ring is required. Even if the pliers are closed to the required closing gap, this can be insufficient if the full force of the pliers is not reached. In order to overcome the rearing forces of the material, the closing gap must be maintained over a certain period of time. In addition, in known pressure medium pliers the achievable closing gap is constant, so that an adaptation to the respective application is only possible by disassembling and installing compensating elements of the pliers head.

CH 651 775 A5 discloses a pressure medium pliers of the type mentioned at the outset, in which two pistons and a feed cone are fixed on a common shaft which has an internal step for driving a collar of a shift rod. A compression spring, which extends over practically its entire length, is mounted in the shaft and presses the piston into its starting position towards the valve. A compression spring presses on the other side of the outer step of the shift rod, which presses the shift rod against a valve pin or into a groove formed therein. This pressure medium pliers is very expensive because of the fastening of both drive pistons on a shaft and the arrangement and extension of the springs during assembly and is limited to two drive pistons.

Proceeding from this, the object of the invention is to provide pressure medium pliers which ensure that the required closing gap is reached with full force build-up and which favors an influencing of the closing forces independent of the working pressure. Embodiments of the pressure medium pliers are intended to allow the closing gap to be easily adapted to the respective application.

The object is achieved by a pressure medium pliers with the features of claim 1. Advantageous configurations of the pressure medium pliers are specified in the subclaims.

The pressure medium pliers according to the invention have a positive control, which forces that after actuation of the pressure medium valve, the piston must be pressurized with pressure medium until the required closing gap is set and the full force is built up and the piston is not relieved of pressure beforehand. For this purpose, a switching rod is held in a guide in the direction of movement of the drive piston and relatively movable relative to it, which is biased by a spring between the switching rod and an abutment in the housing towards the valve pin of the pressure medium valve. The shift rod has a driver and the piston is provided with a stop for taking the shift rod in the last part of its movement for driving the feed member and closing the pliers halves. Furthermore, the valve pin has a locking seat into which the switching rod engages under the action of the spring when the valve pin moves from its rest, which relieves the piston of the pressure medium, into its working position, which pressurizes the piston with pressure medium. When the pressure medium valve is actuated, the selector rod engages in the locking seat and initially prevents the valve pin from returning to the rest position, even if the trigger is released. A return of the valve pin to its rest position is only possible when the shift rod on its driver is carried along by the associated stop of the drive piston. However, this is only the case in the last section of the movement of the drive piston. As a result, the piston is always forced from its initial position into an end position in which the pliers reach the required closing gap over a sufficient closing period. The release of the trigger then causes the drive piston and the tong insert halves to return to their starting position. In this way, a "self-controlling" pliers is achieved, which ensures the required work result and thus a considerable increase in quality causes. In particular, this meets the requirements of the automotive industry and newer standards, which provide for a shift in quality assurance to the production facilities.

In the pressure medium pliers according to the invention, the pressing of the switching rod against the valve pin by means of a spring and the entrainment of the switching rod in the end region of the feed movement are solved much more easily than in the prior art. In addition, the invention enables a modular adjustment of the pressure medium pliers to different force requirements. As far as the pre-tensioning of the selector rod is concerned, this is achieved by supporting the spring on the intermediate wall between the pressure medium valve and the drive piston. As far as the entrainment of the shift rod is concerned, this is achieved in that the adjacent drive piston is T-shaped and has the inner step in its shaft, which is only supported on the following drive piston. Means for engaging and taking the shift rod are limited to the intermediate wall and the adjacent drive piston. Other drive pistons do not take up these construction elements and can be manufactured, assembled and staggered in succession in the number required for the required clamping force will. Only the length of the housing has to be adapted to the number of pistons. This can be done simply by producing pipe pieces of appropriate length, which are screwed on one end to the working part and on the other end to the control part. Furthermore, partition walls for guiding further T-shaped drive pistons can be arranged on their shafts in the housing.

According to a preferred embodiment, the shift rod engages in the locking seat before the valve pin reaches its working position. This enables an intermediate position between the rest and working position, in which the tong insert halves are not pivoted despite the actuation of the trigger.

In individual cases, for example to avoid accidents, it may be necessary to prematurely abort the closing process of the pliers. For this purpose, a trigger pin can be held in the valve pin, which can be displaced towards the shift rod by pressing a vent button and presses it out of the locking seat. The valve pin can then return to its rest position, in which the pliers open again.

The valve pin preferably has an elongated groove, into which an alignment pin engages, which correctly aligns the valve pin and thus the locking seat or release pin.

An intermediate wall is preferably fixed in the housing, on which the spring is supported or which holds the guide for the shift rod. The partition can also limit the piston movement.

A plurality of staggered drive pistons are preferably provided for the pressure transmission, which are T-shaped and have a pierced shaft, as described in detail in DE-GM 87 16 694 mentioned at the beginning. In the case of a T-shaped piston with a shaft drilled through and directed towards the feed element, the shift rod, with its driver designed as an external step, can protrude into the bore in which the stop of the drive piston is designed as an internal step.

To adjust the minimum closing gap, the pliers insert halves can be held on an annular pliers head, which in turn is held on the housing of the pressure medium pliers by means of an annular thread guide. An adjusting thread is then formed between the pliers head and the thread guide, which enables the pliers head to be moved axially relative to the housing. By adjusting the pliers head, the position of the pliers halves relative to the feed member is changed, which changes the minimum closing gap. Is preferred An index screw is provided between the pliers head and the thread guide to fix the parts in different screw positions. The pliers head and thread guide can also carry markings to indicate the different screw positions.

For angular alignment of the pliers head on the housing and the trigger arranged thereon regardless of the setting of the setting thread, the thread guide can have an external step, which is overlapped by the flange of a locking ring for fixing to the housing. By loosening the locking ring and turning the thread guide, the desired alignment is achieved without changing the axial position of the pliers head.

A further setting can be realized in that the pressure medium valve is accommodated in a valve housing, which is connected at the end of the housing opposite the pliers insert halves to the latter via a further adjusting thread. By adjusting the valve housing, it can be influenced in which position of the drive piston the locking of the valve pin is released and the minimum closing gap is reached. This enables length compensation for the shift rod during assembly. This option will be used less often so that preferably the further adjusting thread is equipped with a locking ring for clamping the valve housing and housing.

Fig. 1

die Druckmittelzange unter Weglassung des Auslösehebels bei Betätigung mit den Antriebskolben in der Ausgangsstellung im Längsschnitt;

Fig. 2

die Druckmittelzange mit abgesprengtem Auslösehebel nach Auslöserbetätigung mit den Antriebskolben in der Endstellung im Längsschnitt;

Fig. 3

Vorderteil der Druckmittelzange in derselben Situation wie Fig. 1 in vergrößertem Längsschnitt;

Fig. 4

Vorderteil der Druckmittelzange in derselben Situation wie Fig. 2 in vergrößertem Längsschnitt;

Fig. 5

Hinterteil derselben Druckmittelzange in derselben Situation wie Fig. 1 in vergrößertem Längsschnitt;

Fig. 6

Hinterteil derselben Druckmittelzange in derselben Situation wie Fig. 2 in vergrößertem Längsschnitt.

Further details and advantages of the invention emerge from the following description of the attached drawings of a preferred exemplary embodiment. The drawings show:

Fig. 1

the pressure medium pliers with the release lever omitted when operated with the drive piston in the starting position in longitudinal section;

Fig. 2

the pressure medium pliers with a detached release lever after actuation of the trigger with the drive piston in the end position in longitudinal section;

Fig. 3

Front part of the pressure medium pliers in the same situation as Figure 1 in an enlarged longitudinal section.

Fig. 4

Front part of the pressure medium pliers in the same situation as Figure 2 in an enlarged longitudinal section.

Fig. 5

Rear part of the same pressure medium pliers in the same situation as Figure 1 in an enlarged longitudinal section.

Fig. 6

Rear part of the same pressure medium pliers in the same situation as Fig. 2 in an enlarged longitudinal section.

As can be seen from FIGS. 1 and 2, the pressure medium pliers essentially consist of three parts: the working part 1, the drive part 2 and the control part 3.

3 and 4, the working part 1 has a substantially ring-shaped pliers head 4, which on both sides protrudes at the ends 5, 6 projecting from the front by means of bolts 7, 8, side parts of which only the rear side part is shown in the sectional views 9 is shown.

The two side parts, which are arranged parallel to the plane of the drawing, are penetrated by insert bolts 10, 11, which pivotly insert the pliers insert halves 12, 13. The pliers insert halves 12, 13 carry rollers 16, 17 on their inner lever ends 14, 15. The pliers insert halves are pushed apart at their outer lever ends by a spring (not shown) at most so far that the rollers 16, 17 touch one another.

The pliers head 4 has an inner step 18. This is a front outer step 19 of a substantially ring-shaped Thread guide 20 assigned. An adjusting thread 21 is formed between the inner step 18 and the front outer step 19.

In addition, there is a centering pin 22 in the separation area between the pliers head 4 and the thread guide 20, which has a threaded seat in the pliers head 4 (it is arranged between the ends 5, 6 and is shown offset by 90 °) and engages with a centering in a blind hole 23 from which are distributed several around the central axis of the thread guide 20.

The thread guide 20 also has a rear outer step 24 which is overlapped by the inward flange of a locking ring 25 which is screwed onto a retracted thread 26 of a cylindrical housing 27 of the drive part 2.

The drive part 2 has a feed member 28 protruding from the front of the housing 27, which is directed with a wedge-shaped end 29 towards the inner lever ends 14, 15 or rollers 16, 17. The feed member 28 is fastened by means of a locking screw 30, which passes through a sleeve 31, to a piston disk 32, which is sealed on the outer circumference to the housing 4 and is axially movably guided therein.

Between the threaded guide 20 and the piston disk 32 there is a further sleeve 33 which forms a stop for the piston disk 32. In addition, a return spring 34 is arranged between the threaded guide 20 and the piston disk 32, which biases the piston disk 32 away from the head part 1. The return spring 34 pushes the piston disk 32 back after pressure relief up to an annular disk-shaped intermediate wall 35 of the housing 4.

As can be seen better from FIGS. 5 and 6, the housing 4 is divided by two further essentially annular disk-shaped intermediate walls 36, 37. All partitions 35, 36, 37 are fixed to the inner wall of the housing 4 and sealed against it.

Shafts 39, 40 T-shaped pistons 41, 42 are sealingly guided in the intermediate walls 35, 36 or their central openings 38. The piston disks 43, 44 of the pistons 41, 42 are guided in a sealed manner on the inner wall of the housing 4. The shafts 39, 40 and piston disks 41, 42 are each provided with a central through hole 45, 46, so that compressed air let in by the control unit 3 simultaneously hits the piston disks 32, 43 and 44 and pushes them towards the working head 1. The stems 39, 40 press against the adjacent piston disks 32, 43, whereby a considerable pressure increase occurs. So that the pressure medium can emerge from the seated shaft ends, diametrical outlet openings 47, 48 are formed there, through which the pressure medium reaches the effective piston end faces.

A tubular guide 49 is held in the end wall 37, which is adjacent to the control part 3. The guide 49 is in the direction of movement of the pistons 32, 41, 42, i.e. axially aligned in the housing 4. With one end 50, the guide 49 projects beyond the intermediate wall 37. On the other hand, it protrudes into the bore 46 and is supported in this by a guide ring 51. The guide 49 guides a switching rod 52 which protrudes from the latter at both ends. At the end facing the working part 1, the switching rod 52 carries a driver 53 in the form of a radially projecting bushing outside the guide 49. The driver 53 is assigned a piston-fixed stop 54 in the form of an inner step of the through hole 46.

The other end of the shift rod 52 extends into the control part 3. It is pretensioned in this direction by a helical spring 55, which is supported at one end on the end face of the guide and at the other end on a ring 56 fastened to the shift rod 52.

The control part 3 receives the associated end 57 of the shift rod 52 in a bore 58 of a valve housing 59 which also guides it. The valve housing 59 has a transversely directed, stepped bore 60 in which a valve pin 61 is seated. The valve pin 61 has a locking seat 62 in the form of an axially directed groove which can receive part of the end 58 of the switching pin 52. The valve pin 61 has a further axially directed groove 63, in which a housing-fixed alignment pin 64 engages. At one end, the valve pin 61 is held in a valve bushing 65, with an O-ring 66 arranged between them.

The other end of the valve pin 61 is associated with a spherical valve body 67 which is arranged behind a sealing plug 68 which is sealed off from the housing 59. A further O-sealing ring 70 is located between an inner step 69 of the bore 60 and the valve body 67. The section of the bore 60 containing the valve body 67 has a pressure medium connection 71.

A small trigger pin 72 is guided in the valve pin 61 and is aligned with the shift rod 52 and can be pressed into the locking seat 62. For this purpose, an outwardly projecting vent button 73 is arranged in the housing 59 can be pressed in against the action of a spring 74 and in the process pushes the trigger pin 72 toward the switching rod 52.

On the outside of the valve housing 59, a protruding end of the valve pin 61 is associated with a one-armed trigger lever 75 (see FIG. 2). On this side, the valve housing 59 has a blind bore 76 in which another spiral spring 77 is seated, which presses the trigger lever 75 outwards.

The valve housing 59 has a cylindrical projection 78 which is screwed to the associated end of the housing 4. For this purpose, a further adjusting thread 79 is provided. A further threaded ring 80 is also assigned to the further adjusting thread 79 for securing against jamming.

Finally, reference is made to passages 81, 82 of the housing 4, which vent the piston disks 43, 44 on the side facing the working part 1. The piston disk 32 can be adequately ventilated in this direction by the working part 1.

This device works as follows: when the trigger is not actuated, all pistons 32, 41, 42 are in the starting position, ie are moved at most to the control part 3 under the action of the spring 34. The shift rod 52 is pressed against the valve pin 61 by the pressure of the spring 55. The valve pin 61, which is not loaded by the trigger lever 75, is pressed by the pressure medium out of the pressure medium connection 71 in the direction of the trigger, but is secured in the valve housing 59 by the alignment pin 64 or trigger pin 72. In this position, the shift rod 52 does not engage in the locking seat 62. The pliers insert halves 12, 13 are pivoted apart to a maximum.

When the trigger lever 75 is actuated, the switching rod 52 first engages in the locking seat 62 of the valve pin 61 due to the tension of the spring 55 (FIGS. 1, 3 and 5). Then the valve body 67 is pressed by the valve pin 61 out of the seat in the O-ring 69. Pressure medium from the pressure medium connection 71 flows through gaps between the bore 60 and valve pin 61 and a - not shown - bore of the valve housing 59 in the housing 4 and spreads through an axial passage of the intermediate wall 37 or the through holes 46, 45, so that all Pistons 32, 41, 42 are pressed towards working part 1.

About 1.5 mm before the pistons reach their end position, in the minimum by the action of the feed member 28 Closing gap between the pliers insert halves 12, 13 is set, starts the pulling of the switching rod 52 from the locking seat 62 of the valve pin 61 due to the engagement of the driver 53 on the stop 54.

In the end position of the pistons 32, 41, 42, the valve pin 61 is completely free, i.e. when the set closing gap between the tong insert halves 12, 13 is reached, the pistons can be vented by releasing the trigger lever 75 (FIGS. 2, 4 and 6). Then namely the compressed air drives the valve pin 61 back to the rest position, in which the housing 4 is vented to the environment via the - not shown - bore of the valve housing 59 and the gap between the valve pin 61 and bore 60 and bushing 65. Then the pistons are moved again to the control part 3 by the pressure of the spring 34 and the initial situation is reached again.

If, after actuation of the trigger lever 75, the end position of the pistons or the minimum closing gap of the pliers insert halves 12, 13 has not yet been reached, the switching rod 52 prevents the pistons from being vented by locking the valve pin 61 when the valve lever 75 is released. The switching rod is then namely still locked in the locking seat 62 of the valve pin 61.

However, manual venting is possible at any time by pressing the vent button 73.

The switching rod 52 is pressed out of the locking seat 62 of the valve pin 61 by means of the trigger pin 72. The pistons are then vented as previously described.

A change in the minimum closing gap of the pliers insert halves 12, 13 is possible by an axial displacement of the pliers head 4 to the feed member 28. By rotating the pliers head 4 on the threaded guide 20, the axial displacement to the wedge 28 is achieved. The pliers head 4 is then indexed again by means of the index screw 22. The rotation around an "index point" e.g. correspond to a change in the closing gap of 0.1 mm.

A "fine adjustment" of the trigger point of the ventilation is carried out by turning the valve housing 59. Before this, its clamping must be released by means of the threaded ring 80 on the housing 4. After the fine adjustment, the valve housing 59 is secured against the valve housing 59 by tensioning the threaded ring 80.

If the pressure medium pliers should be made stronger, can between pistons 41 and 32 with a corresponding Extension of the tubular housing 4 further pistons and partitions can be arranged, which are designed like the piston 41 and the intermediate wall 35. The pliers can be adapted to the respective requirements in a modular manner.

Claims (12)

Pressure medium pliers for clamping rings and the like, with a pressure medium connection (71) and a pressure medium valve (60, 61, 66, 67, 69) connected to it, a plurality of drive pistons (32, 41, 42) controlled by the pressure medium valve, and a feed member that can be driven by the drive piston ( 28) and pivotably mounted pliers insert halves (12, 13), on the inner lever ends (14, 15) of which the feed member engages in order to pivot them, the pressure medium valve (60, 61, 66, 67, 69) being displaceable in the transverse direction of the piston movement guided and actuated by a trigger (75) has valve pin (61) which, in a rest position, blocks the connection of the drive pistons (32, 41, 42) to the pressure medium connection (71) and connects them to a lower pressure level and which in one operation the trigger (75) reachable working position blocks the connection of the drive piston with the lower pressure level and this (32, 41, 42) with the pressure medium connection Det, wherein a switching rod (52) is held in a guide (49) in the direction of the drive pistons (32, 43, 44) and is biased by a spring (55) to the valve pin (61), the switching rod (52) an outdoor stage as driver (53) and the drive piston, a drilled shaft receiving the shift rod (52) with an inner step assigned to the outer step (53) as a stop (54) for taking the shift rod in the last section of its movement to close the pliers insert halves (12, 13) and wherein the valve pin (61) has a locking seat (62) into which the switching rod (52) engages under the action of the spring (55) when the valve pin (61) moves from rest to the working position and which the switching rod (52) releases them when they are carried by the drive piston (42), characterized in that an intermediate wall (37) is fastened to the housing between the pressure medium valve (60, 61, 66, 67, 69) and the drive piston (32, 41, 42) supports the spring and that the drive piston (42) arranged next to the intermediate wall (37) is T-shaped and supports the shaft (40) directed towards the feed member and having the internal step on the following drive piston (41). Pressure medium pliers according to claim 1, characterized in that the switching rod (52) engages in the locking seat (62) before the valve pin (61) reaches its working position. Pressure medium pliers according to claim 1 or 2, characterized in that a release pin (72) is held in the valve pin (61), which can be displaced towards the shift rod (52) by actuating a vent button (73) in order to remove it from the locking seat (62) to press. Pressure medium pliers according to one of claims 1 to 3, characterized in that the valve pin (61) has a longitudinal groove (63) into which an alignment pin (64) engages. Pressure medium pliers according to one of claims 1 to 4, characterized in that the intermediate wall (37) between the pressure medium valve (60, 61, 66, 67, 69) and drive piston (32, 41, 42) holds the guide (49) for the shift rod. Pressure medium pliers according to one of claims 1 to 5, characterized in that the pliers insert halves (12, 13) are held on an annular pliers head (4), that the pliers head (4) is held on the housing (4) by means of an annular threaded guide (20) , and that between the pliers head (5) and the threaded guide (20) an adjusting thread (21) for axially adjusting the pliers head (5) with respect to the feed member (28) is formed. Pressure medium pliers according to claim 6, characterized in that the threaded guide has an outer step (24) which is overlapped by the flange of a locking ring (25) for fixing the threaded guide (20) on the housing (4). Pressure medium pliers according to claim 6 or 7, characterized in that an index screw (22) for fixing the pliers head (5) and thread guide (20) is arranged in different screw positions between the pliers head (5) and the thread guide (20). Pressure medium pliers according to one of claims 6 to 8, characterized in that the pliers head (5) and thread guide (20) carry markings to indicate their screw positions. Pressure medium pliers according to one of claims 1 to 9, characterized in that the pressure medium valve (60, 61, 66, 67, 69) is accommodated in a valve housing (59), and in that the valve housing (59) on the halves of the pliers insert (12, 13 ) opposite end of the housing (4) is screwed to it via a further adjusting thread (79). Pressure medium pliers according to claim 10, characterized in that the further adjusting thread (79) carries a threaded ring (80) for securing the threaded connection between valve housing (59) and housing (4) in different screw positions. Pressure medium pliers according to one of claims 1 to 11, characterized in that they have a plurality of drive pistons (41, 42) staggered one behind the other with a T-shape and a pierced shaft (39, 40).

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