DE1004560B - Device for changing the piston stroke and the impact strength of air hammer - Google Patents

Description

GERMAN

Working with pneumatic impact tools often results in different piston impact strengths necessary. For this purpose, the full pressure medium supply required for the greatest piston impact strength is usually required gradually throttled, thus reducing the piston impact force accordingly. You also have stepped pistons used to make a change through different pressures on the individual piston step surfaces to achieve the piston impact strength. While with the throttle control in addition to a reduction the impact strength and an undesirable reduction in the number of blows is inevitable Using a stepped piston probably changed the impact strength, but not the number of blows, since in In both cases the tools work with an unchangeable piston stroke.

In the practical use of pneumatic impact tools, however, the requirement is made that hard or material of high strength with high impact strength at a low number of blows and softer or material of lower strength with correspondingly reduced impact strength with increased Number of strokes is processed. This requirement occurs particularly when working with rock hammer drills in changing rocks with different hardnesses. The hard rock requires a hammer drill with high impact strength and low impact rate, while for hammer drilling in soft rock, one with a low impact force and high impact rate is required. In such cases you can help yourself by using different hammers with different ones Rock type adapted impact properties are used. However, this leads to a high outlay on equipment; the impact device cannot be adapted quickly enough in the event of a sudden change in the hardness of the material will.

Impact tools with different strokes are cheaper in such cases. The change in stroke of the Percussion piston takes place here by one behind the other by a control element, ζ. Β. a rotary valve, Optionally switchable openings in the front cylinder chamber, which are connected to the valve chamber in Connected. By closing these openings, the valve is reversed later, see above that a larger piston stroke is achieved. However, this known design has the disadvantage that the Cylinder volume above the piston is invariable, which leads to high air consumption as a result of the small strokes large harmful space above the piston leads. It also works with such impact devices necessary early pre-inflow inhibiting the return stroke of the piston; a decrease the number of strokes and the performance are the result.

Facility for change

the piston stroke and the impact force

of pneumatic hammers

Applicant:

Mark Brennkraft-Maschinen G. mb H.,
Wengern / Ruhr, Bahnhofstr. 9

Norbert Wirtlich, Wengern / Ruhr,
has been named as the inventor

These disadvantages are avoided by the invention. This is followed by a change in the percussion piston stroke the usable cylinder length, d. H. the cylinder volume, by longitudinally shifting the control housing varies. This can be done by turning the handle, which, provided with a locking device, for the desired stroke length adjustment at the same time the percussion piston thus rotated that its lower control edges, which are offset from one another in the axial and circumferential directions, into the Be brought to a position in which the outlet of the respective set stroke earlier or later is released.

In each setting of the stroke, the space above the percussion piston is constant.

An exemplary embodiment of the invention is shown in the drawing. It show the

Fig. 1, 2, 3 a longitudinal section through the impact tool with the largest, medium and smallest Piston stroke while

Fig. 4 shows a cross section along the line AB with a plan view of the lower percussion piston surface for the return stroke.

10 is the cylinder with the outlet openings 11, 12 and the inlet opening 13 for the piston return stroke. The cylinder cover 14 with the compressed air inlet connection 15 is firmly screwed onto the cylinder 10. The handle 16 is rotatably arranged on the cylinder cover 14; this has a spring-loaded locking pin 17 to jump into corresponding notches of the cylinder cover 14. With the handle 16 is the Rotary spindle 18 firmly connected, which is located in the cylinder cover 14 and in the cylinder 10 longitudinally displaceable, but non-rotatable control housing 19 rotatable and in the percussion piston 20 by means of a Square 21 sliding leads. The thread adjusting piece 22 is also attached to the rotating spindle 18,

609 839/107

which rotates in the internal thread 23 of the control housing 19. In the sliding control housing 19 is any known control member, in the example shown a control plate 24, arranged, which in known Route the percussion stroke air through the inlet ports 25 and the return stroke air through the inlet port 13 can flow into the corresponding cylinder space.

In the air supply channel 26 of the displaceable control housing 19 open in their cross section different so-called metering openings 27, 28 and 29 for different amounts of working air at the different piston strokes. These metering openings 27, 28 and 29 all receive their air supply through the inlet channel 30 arranged in the cylinder 10 via the annular space 31 in which the air inlet nozzle 15 opens.

On the return stroke side of the piston 20, three height-different control edges 32, 33 and 34 are arranged, which the outlet opening 12 earlier or later depending on the respective stroke setting open and close. With all piston strokes, the blow-out air is always the same Way through the outlet opening 11, which is always controlled or opened only by the upper edge of the piston and is closed, since the piston impact position always remains the same. At 36 there is any Working or insertion tool is referred to, which is acted upon by the piston 20.

Fig. 1 shows the impact tool at the setting for the largest piston stroke, with the locking pin 17 of the handle 16 secures this setting in a corresponding notch of the cylinder cover 14. The working air flows through the inlet connection 15 into the annular space 31 and from here through the inlet channel 30, the dosage opening 27, the air supply channel 26, to the control plate 24, which the Air alternately through the inlet openings 25 for the piston stroke and 13 for the piston return stroke can flow into the relevant cylinder space. The used air passes through the outlet openings 11 and 12 outdoors. The control edge 32 controls the outlet opening 12 for the piston return stroke.

If the impact tool is to work with the mean piston stroke as shown in Fig. 2, the handle 16 rotated until the locking pin 17 jumps back into the associated notch and this position secures. As a result of this rotation of the handle, the rotary spindle 18 also has the threaded adjustment piece 22 accordingly rotated and the control housing 19 pushed further into the cylinder 10 by means of the internal thread 23, as a result of which the metering opening 28 was now connected to the inlet channel 30 and smaller amount of air required for the middle piston stroke according to the cross-section of the metering opening 28 can flow to the control plate 24, which causes the air distribution in the same way as previously described. When twisting the handle 16 but was also at the same time by the Rotary spindle 18 by means of its square 21, the piston 20 rotated so far that now its higher lying control edge 33 overflows the outlet opening 12 and releases the same earlier. To work the Impact tool with the smallest piston stroke according to Fig. 3, the handle 16 is rotated further until the Locking pin 17 jumps back into the associated notch and secures this position. The turning spindle 18 has the control housing in the same way as before with the intermediary of the threaded adjustment piece 22 pushed even further into the cylinder, so that now the metering opening 29 with the inlet channel 30 connection and the amount of air required for the smallest piston stroke to the control plate 24 can flow, with the same, previously described control effects occur. When twisting of the handle 16 but at the same time the piston 20 was turned further, so that now his highest control edge 34 overflows the outlet opening 12 and this corresponding to the smallest Piston stroke releases even earlier. The striking tool is also brought to a standstill in the simplest possible manner by turning the handle so far that none of the metering openings 27, 28 and 29 with the inlet channel 30 has connection. Special shut-off devices for the pressure medium, like them are previously required for impact tools, are therefore omitted.

Claims (4)

Patent claims: 1. Device for changing the piston stroke and the impact force of pneumatic hammers, characterized in that the control housing (19) is longitudinally displaceable in the cylinder (10) is mounted and offset from one another on the percussion piston (20) in the axial and circumferential directions lower control edges (32, 33, 34) are arranged, which after turning the percussion piston in the for respective position of the control housing corresponding position the outlet opening (12) for the piston return stroke steer. 2. Device according to claim 1, characterized in that the displacement of the control housing (19) and simultaneous rotation of the percussion piston (20) by turning the lockable T-handle (16) by means of a single adjusting element firmly connected to the handle (18) takes place. 3. Device according to claim 2, characterized in that in the internal thread (23) provided control housing (19) a threaded piece (22) penetrated by the adjusting element (18) is arranged and the adjusting member in the percussion piston (20) rotatably, but relatively displaceable intervenes. 4. Device according to claim 2, characterized by one which also blocks the supply of fresh air axial position of the displaceable control housing (19). Considered publications:
German patent specifications No. 26 568, 168 779, 570 730. 1 sheet of drawings © 609 839/107 3.57