WO2009127186A1 - Pneumatic hand-held strapping device - Google Patents

Abstract

A pneumatic hand-held strapping device, comprising a valve arrangement (2), by way of which a drive unit of the hand strapping device (1) can be actuated, wherein the valve arrangement (2) comprises a valve tappet (9) supported in a valve housing (11), said tappet at one end (10) being coupled to an actuating lever (12), by way of which it can be displaced from a starting position against a spring force (F) into a switch position, and wherein the valve arrangement (2) comprises a detent piston (20), which independently of the position of the valve tappet (9) pushes a blocking body (18) with a blocking force (S) laterally against the valve tappet (9) by an applied pneumatic pressure. To this end, in the switch position of the valve tappet (9) the pressurized blocking body (18) engages in a detent recess (19) of the valve tappet (9). A detent force (K) resulting from the blocking force (S) is greater than the spring force (F). The valve tappet (9) can be displaced back into the starting position when the actuating lever (12) is restored to its original position, or, in the depressurized state, solely by the spring force (F).

Description

 Pneumatic hand strapping device

The invention relates to a pneumatic Handrareifungsgerät with the features of claim 1.

Hand strapping tools are used to apply a strapping band made of plastic, steel or similar materials. By means of Hand strapping the strapping band is stretched, the ends of the strapping band are connected together and excess strapping band is separated.

The bonding of the ends of the strapping band can be effected in particular via closure sleeves. It is state of the art to cut the sealing sleeves together with the inner strapping band several times laterally and to bend out the resulting side straps from the original plane of the closure sleeves, so that both band ends are connected to one another by the lateral displacement of the straps within the closure sleeve. For cutting and embossing the closure sleeves high forceps are required. It is important that the operator of such Hand strapping tool does not accidentally come in contact with these pliers, as this can lead to dangerous bruising. On the other hand, however, it must also be ensured that the application of the closure sleeves takes place absolutely reliably and is not interrupted by the user of the hand strapping device without a particular reason, since otherwise a secure closure of the strapping can not be ensured. Therefore, such Handrareifungsgeräte usually have a latching function, which ensures that a piston over which the pliers are operated, undergoes a full stroke. However, this latching function can be dangerous if a pressureless straightening device is to be reconnected to a compressed air connection and put into operation. If the detent is active at this moment, the piston is displaced immediately with the pressurization and the pliers are actuated. On the other hand, these locking mechanism for reasons of Umreifungssicherheit also not be waived.

On this basis, the invention is based on the object to provide a pneumatic Handrareifungsgerät, which is ensured in correct handling that a closure mechanism for pressing the closure sleeves is not triggered when the non-pressure Handrareifungsgerät is pressurized, i. is put into operation.

This object is solved by the features of patent claim 1.

Advantageous developments of the inventive concept are the subject of the dependent claims.

The Handrareifungsgerät invention comprises a valve assembly, via which a drive unit, which is in particular formed by a piston-cylinder unit, the Handrareifungsgeräts can be controlled. The piston is coupled to a closure mechanism for the closure sleeve closure. The valve assembly serves to control the piston or a pneumatic motor, which can be used instead of the piston. For this purpose, the valve arrangement comprises a valve tappet mounted in a valve housing, which is coupled at one end to an actuating lever. About the actuating lever, the valve stem can be moved from a closed position against a spring force in a switching position. In the switching position, the piston is pressurized and the shutter is executed.

An essential element of Handumreifungsgeräts invention is a locking piston, which urges a locking body with a locking force laterally against the valve stem regardless of the position of the valve stem by an applied pneumatic pressure. The pressurized locking body engages in the switching position of the valve stem in a recess of the valve stem. In this case, the locking force resulting from the locking force is greater than the spring force. The valve stem is upon return of the actuating lever, overcoming the latching force or upon pressure release of the locking piston, i. when the applied pneumatic pressure falls below a minimum pressure, only by the spring force displaced back into its closed position.

Important in the invention is that the locking function is only given when the pneumatic Handaufreifungsgerät is pressurized. In the de-pressurized state, the spring force pushes the valve tappet into its initial position, so that unintentional locking and thus triggering of the tongs is impossible. The geometry in the region of the recess is chosen so that adjusts a latching force acting transversely to the blocking force, ie against the effective direction of the spring force, the locking force should only be so large that the detent can be easily canceled manually.

It is theoretically not excluded that an operator actuates the operating lever when connecting the Handaufreifungsgerätes to a compressed air source and thereby unintentionally displaced the valve stem in a switching position in which the valve stem can engage. For this case of incorrect operation is provided in an advantageous embodiment of the inventive idea that the valve stem via a Emergency stop switch is displaced to its initial position. The force required for this purpose preferably corresponds approximately to the force that is necessary to pull the operating lever.

The emergency stop switch can be connected in a space-saving manner with the remote from the actuating lever end of the valve stem, so that it can be actuated with the thumb of the user's hand. This allows one-handed operation both in terms of triggering the shutter mechanism and the emergency release of the lock function.

It is considered expedient if the spring force acts on the end remote from the actuating lever of the valve stem. In this case, the spring may even be integrated into the valve housing and is therefore protected against manipulation and contamination. This ensures reliable operation of the safety mechanism.

Alternatively, the spring force also act indirectly on the actuating lever on the valve stem. The spring is arranged in this case on the operating lever. The spring can surround the lower end of the valve stem as a helical compression spring, which thus serves as an inner guide for the spring.

The provision of the valve stem is carried out in an advantageous embodiment by a return ram, which is arranged virtually on the underside of a piston of the drive unit receiving cylinder housing. The piston presses in its end position on this return ram, which in turn exerts a restoring force on the valve stem. The restoring force can be diverted via the operating lever, i. be transmitted indirectly.

Essential in the design of Handrareifungsgeräts is the vote of the forces acting on the valve stem. In this context, it is provided that a contact region between the locking body and the recess is designed as inclined to the stroke direction of the valve stem and the stroke direction of the locking piston extending inclined surface. Sloping surfaces may be formed on one or on both components in contact with each other. It is crucial that it does not come to a self-locking, so that the locking body can be pushed out of the recess only by the spring force.

It is considered expedient if the blocking body has the shape of a ball cap. Such a blocking body can, for example, grasp in a recess formed as an annular groove, the edges of which are provided in the transition to the outside of the valve stem with chamfers, i. Have inclined surfaces. In a particularly advantageous embodiment, the chamfers are at an angle of 30 ° to the stroke direction of the locking piston.

The invention can be best understood and explained with reference to the following diagrammatically illustrated drawings. It shows:

Figure 1 shows a portion of a pneumatic Handumreifungsgeräts in

Section of its valve assembly in partial section, the device is depressurized and the valve stem is in an initial position;

Figure 2 shows the pneumatic Handumreifungsgerät of Figure 1 in the unpressurized state, wherein the valve stem is in its switching position;

Figure 3 shows the pneumatic Handumreifungsgerät of Figure 2 in the switching position, wherein the locking piston is pressurized and presses a locking body in a recess of the valve stem;

FIG. 4 shows the pressurized hand strapping apparatus of FIG. 3 at the end of the closing operation, with the piston in its lower stroke position;

Figure 5 in an enlarged view of the valve stem with engaging

Lock body and locking piston and Figure δ in an enlarged view of the geometry of the recess on the valve stem.

Figure 1 shows the essential to the invention range of a pneumatic Handumreifungsgeräts 1 with a valve assembly 2, which is located in the immediate vicinity of a cylinder 4, in which a piston 5 is displaced. The valve arrangement 2 is located between the cylinder 4 and a handle 6 with end-side compressed air connection 7. The compressed air connection 7 is a commercially available hose coupling. About the compressed air connection 7 and a longitudinally extending within the handle 6 compressed air channel 8, the valve assembly 2 can be acted upon pneumatically. An essential part of the valve assembly 2 is a valve stem 9, which protrudes in the image plane lower end 10 of the integrally formed with the handle 6 valve housing 11 and is connected to an actuating lever 12. The actuating lever 12 is articulated below the cylinder 4 and is pulled by the operator in the direction of the handle 6 upon actuation of the hand strapping device 1. The operation is carried out by means of the index finger, while the palm rests on the top of the handle 6.

By the actuating lever 12, the valve stem 9 can be displaced upwardly within the valve housing 11 in the image plane, as shown in Figure 2. The displacement takes place against a spring force F, which starts from a helical compression spring 14 which is disposed at the top, remote from the actuating lever 12 end 15 of the valve stem 9 and on the one hand against the valve housing 11 and on the other hand against a collar 16 of the valve stem 9 is supported. In Figure 2 it can be seen that the valve stem 9 is in the switching position with its lower end 10 within the valve housing 11, wherein its upper end 15 is displaced out of the valve housing 11 also. This upper end 15 serves as an emergency stop switch 17, which can be operated with a thumb by the widened head 3 of the emergency stop 17 is pressed down again in the direction of the valve housing 11, so that the valve stem 9 is displaced downwards. In FIGS. 1 and 2, no pressure is applied to the hand strapping apparatus 1. As a result, the piston 5 remains in the illustrated upper position. Important in this context is that the valve stem 9 does not latch in the switching position shown in Figure 2.

The latching function of the valve assembly 2 is realized by the interaction of a locking body 18 and a latching recess 19. In this embodiment, the locking body 18 is integrally formed on a locking piston 20. The locking body 18 has the shape of a ball cap. The latching recess 19 is formed as a latching groove (Figure 5). Important in this context is that the locking body 18 is not held in the self-locking recess 19, but is displaced by displacement of the valve stem 9 in its stroke direction H1 from the recess 19. For this purpose, the contact area between locking body 18 and locking piston 20 is formed as an inclined surface. In the present embodiment, both the contact surface of the locking body 18 is beveled, namely by the shape of the ball cap, as well as the contact area of the valve stem 9. The recess 19 has chamfers 21 in transition to the outside 22 of the valve stem 9. In Figure 6 it can be seen that the chamfer 21 is at an angle W of 30 ° to the stroke direction H2 of the locking piston 20.

The force acting in the stroke direction H1 of the valve stem 9 spring force F causes the valve stem 9 is always in the starting position, unless this is pulled by the operating lever 12 against the spring force F up in the switching position. A latching in the starting position is not possible because the locking recess 19 is not in the initial position of the valve stem 9 in the amount of the locking body 18. This is pressed in the starting position against a shaft portion 23 which has a larger diameter than the latching recess 19th

If, during the application of the pneumatic pressure, the operating lever 12 is inadvertently pulled, so that the valve stem 9 in the Shift position is located and the locking piston 20 presses the locking body 18 in the recess 19, the valve stem 9 can be pressed over the emergency stop 17 by overcoming the blocking force S immediately down to prevent a shutdown of the piston 5. This difference will be apparent from Figures 2 and 3. While the Handrareifungsgerät 1 is depressurized in Figure 2 and the locking body 18 is thus not in the recess 19, in the embodiment of Figure 3 is a pressure p in the compressed air channel 8 at. The compressed air channel 8 is connected to a transverse channel 24, via which the pressure p acts on the side facing away from the locking body 18 side of the locking piston 20 and thus pushes the locking body 18 in the locking receptacle 19. Figure 3 thus shows the latched position in which the valve assembly 2 is in the switching position. The pressure p acts on the piston 5, which thereby moves downward within the cylinder 4 and in its lower position touches a return ram 25 and finally displaces it (FIG. 5). The restoring plunger 25 presses on the actuating lever 12, which exerts a restoring force R on the lower end 10 of the valve stem 9 and thereby overcomes the latching force K and by supporting the spring force F the valve stem 9 down to the starting position, thereby canceling the detent becomes.

If the latching force K resulting from the blocking force S is overcome once, the spring force F automatically presses the actuating lever 12 into the starting position, wherein the valve switches, the piston 5 moves upward again and the hand-strapping device 1 is available for another strapping operation.

The spring force F thus also prevents the independent switching of the valve assembly 2, so that the Handumreifungsgerät 1 can trigger automatically either in the pressureless or pressurized state. An unintentional locking of the locking body 18, for example, during the transport of Handumreifungsgeräts 1 is excluded by the inventive design of the valve assembly 2. Injuries due to an unwanted forceps movement when connecting the Handaufreifungsgeräts 1 on The compressed air supply can therefore also be excluded. The emergency stop switch 17 provides additional security in case of incorrect handling of Handrareifungsgeräts. 1

Reference numerals:

1 - Hand strapping tool

2 - valve assembly 3- head

4 - cylinder

5 - piston 6- handle

7 - Compressed air connection

8 - Air duct 9- valve lifter

10 - lower end v.9

11 - Valve housing

12- operating lever

13- top v.6

14- helical compression spring

15 - upper end v.9

16 - collar

17- Emergency stop switch

18- locking body

19- latching recess

20- locking piston

21 - Chamfering

22 - Outside 23- Shaft section 24 - Cross channel 25- Reset rams F spring force

R restoring force

S - blocking force

K-latching force

W angle

H1 - stroke direction v.9

H2 - stroke direction v.20 p - pressure

Claims

claims 1. Pneumatic Handrareifungsgerät with a valve assembly (2) via which a drive unit of Handrareifungsgeräts (1) is controllable, wherein the valve assembly (2) in a valve housing (11) mounted valve stem (9), which at one end (10) with an actuating lever (12) is coupled, via which it is displaceable from a starting position against a spring force (F) in a switching position and wherein the valve assembly (2) has a locking piston (20), which regardless of the position of the valve stem (9) by an applied pneumatic pressure a locking body (18) with a blocking force (S) laterally against the valve stem (9) urges, wherein the pressurized locking body (18) in the switching position of the valve stem (9) in a latching recess (19) of the valve stem (9 ) engages and wherein one of the locking force (S) resulting detent force (K) is greater than the spring force (F), wherein the valve stem (9) at Rückste Luling the operating lever (12) by overcoming the latching force (K) or in the pressureless state only by the spring force (F) is displaced back to its original position. 2. Handrareifungsgerät according to claim 1, characterized in that one of the valve tappet (9) via an emergency stop switch (17) is displaceable into its initial position. 3. Handrareifungsgerät according to claim 1 or 2, characterized in that the emergency stop switch (17) with the actuating lever (12) facing away from the end (15) of the valve stem (9) is connected. 4. Handrareifungsgerät according to claim 3, characterized in that the emergency stop switch (17) on an upper side (13) of a handle (6) of the Handaufreifungsgeräts (1) and arranged for actuation with a Thumb the hand of a user is provided, with this hand also the actuating lever (12) is actuated. 5. Handrareifungsgerät according to one of claims 1 to 4, characterized in that the spring force (F) on the actuating lever (12) facing away from the end (15) of the valve tappet (9) engages. 6. Handrareifungsgerät according to one of claims 1 to 5, characterized in that the drive unit is formed by a piston-cylinder unit, wherein one of the piston (5) of the piston-cylinder unit displaceable return ram (25) is provided, which in an end position of the piston (5) at least indirectly exerts a restoring force (R) on the valve tappet (9). 7. Handrareifungsgerät according to claim 6, characterized in that the restoring plunger (25) exerts a restoring force (R) on the actuating lever (12). 8. Handrareifungsgerät according to one of claims 1 to 6, characterized in that a contact area between the locking body (18) and latching recess (19) as to the stroke direction (H1) of the valve stem (9) and the stroke direction (H2) of the locking piston (20) inclined extending inclined surface is formed. 9. Handrareifungsgerät according to claim 8, characterized in that the locking body (18) has the shape of a ball cap. 10. Handrareifungsgerät according to claim 8 or 9, characterized in that the latching recess (19) is formed of annular groove, wherein chamfers (21) at their edges in the transition to the outer side (22) of the valve stem (9) are provided. 11. Handrareifungsgerät according to claim 10, characterized in that the chamfers (21) at an angle (W) of 30 ° to the stroke direction (H1) of the locking piston (20).