CH664319A5 - DRILLING HAMMER. - Google Patents

Description

DESCRIPTION The invention relates to a hammer drill according to the preamble of claim 1.

The invention can be used in mechanical engineering and other branches of industry for the production of bores in rocks and building materials and for the destruction thereof.

A hammer drill known from DE-PS 2 938 513 has a drive member, a tool and a cylinder housed in a housing, in which a drive piston connected to the drive member is arranged, which has an air cushion with a percussion piston and the tool connected to it cooperates. The drive piston is connected to a connecting rod which is mounted on an axle which is in a rotatable socket, the shaft of which is kinematically connected to a pair of bevel gears. This hammer drill also contains friction elements which are attached to the housing and brake the bevel gear pair mentioned. In such a hammer drill, the adhesion of the brake elements depends on the force that is applied to the housing of the hammer drill during work.

The greater this force, the better the friction elements adhere, which reduces their slippage and increases the stroke frequency of the impact piston. At the same time as the stroke frequency increases, the energy of the single stroke of the impact piston increases. However, the reliability of this known hammer drill is relatively low due to the constant wear of the friction elements. As a result, there is only a narrow control range for controlling the impact energy of the percussion piston.

Another hammer drill, known from US Pat. No. 1,402,727 (dated January 3, 2002) according to the preamble of claim 1, has a bushing which is longitudinally displaceable relative to the cylinder and spring-loaded with respect to the same. The control area of this bush is formed in the form of a row of bores arranged longitudinally to the bush.

The force of the spring is overcome by a force applied to the housing of the known hammer drill, so that the bush moves in the axial direction relative to the cylinder. This shift brings about a successive correspondence of the bores arranged in the bushing with the compensating bores arranged in a graduated manner in the cylinder. The maximum impact force is achieved when the air cushion is connected to the surrounding atmosphere via the top compensating hole, which is located directly below the end face of the drive piston when it is at bottom dead center. If the pressure is equalized via a lower compensation hole, the impact force is reduced. The total cross section of the compensating holes increases. This reduces the vacuum level of the air cushion when the piston moves away from the percussion piston, thereby reducing the stroke of the percussion piston. When the drive piston moves in the direction of the percussion piston, the air losses from the air cushion increase, which reduces the speed of movement of the percussion piston in the direction of impact. This decrease results in a lower impact.

A further increase in the force applied to the housing of the hammer drill results in the air cushion being connected to the surrounding atmosphere by means of a further compensating hole, which is set back a further step in relation to the uppermost compensating hole. This results in a further enlargement of the entire cross-section of the compensating holes and a further reduction in the impact force. The control range of the impact force is insufficient with this known hammer drill.

When working with this known hammer drill, conditions arise for premature closing of the opened compensating bore, which is set back from the uppermost compensating bore, by the drive piston if it is located above the upper compensating bore or by the percussion piston if this compensating bore is below the uppermost compensating bore. The duration of the connection of the air cushion to the atmosphere via this compensating bore during the period between two successive strikes of the percussion piston is reduced if there is no possibility of using this compensating bore to reduce the impact force to the full extent. The further the equalization hole is from the uppermost equalization hole, the less time it takes to connect the air cushion to the atmosphere during the period between two successive blows, and the less it affects the reduction in impact. As a result, there is no possibility of regulating the impact within further limits.

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The invention has for its object to provide a hammer drill with a significantly expanded control range of the impact force by the compensating holes are optimally stressed in the period between two successive blows.

The object is achieved according to the invention by the features specified in the characterizing part of claim 1.

As a result of the arrangement according to the invention, the compensating bores are in such a position that they can be optimally used. This means that the impact can be reduced within a large range.

By a preferred embodiment according to claim

2, it is also possible to reduce the external dimensions of the hammer drill and consequently to reduce its mass.

In a preferred embodiment according to claim

3, the reliability of the hammer drill can be increased.

An embodiment according to claim 4 is characterized by a particular simplicity in manufacture.

In one embodiment according to claim 6, the manufacture of the socket is particularly simple because it can be carried out with an annular groove for operative connection with an actuating lever.

With the hammer drill claimed, a wide control range of the impact force can be achieved, for example in order to increase the drilling performance independently of the strength of the material to be processed and also to increase the reliability of such a hammer drill.

Exemplary embodiments of the invention are explained in more detail with reference to the drawings. It shows:

1 is a hammer drill in longitudinal section with a sleeve rotatably arranged relative to the cylinder,

2 shows a cross section II-II according to FIG. 1 in a position of the bushing in which one of four compensating bores is open,

3 shows a cross section with two open compensation holes,

4 shows a cross section of another embodiment with a fixed bushing and a rotatable cylinder,

5 shows a cross section through a further embodiment with a bushing made in one piece with the housing,

6 is a partial view of a further embodiment of a longitudinally displaceable bush,

Fig. 7 shows another embodiment with a longitudinally displaceable bushing and

Fig. 8 is a diagram for explaining the controllable impact force.

The hammer drill shown in FIG. 1 has a housing 1 in which a drive element 2, a tool 3 and a cylinder 4 are arranged. Arranged within the cylinder 4 are a drive piston 5 coupled to the drive element 2 and a percussion piston 6 acting on the tool 3. The drive piston 5 has a piston seal 7 and the percussion piston 6 has a piston seal 8. The two pistons 5 and 6 are operatively connected via an air cushion 9, as a result of which the percussion piston 6 is moved periodically in time with the movements of the drive piston 5 to generate the impact force.

Below the end face 10 of the drive piston 5, which is in its bottom dead center position, 4 compensating bores 11, 12, 13 and 14 are arranged in a plane perpendicular to the axis of the cylinder 4 in the wall of the cylinder 4. Since the compensating holes are distributed over the circumference, the compensating hole 13 is not visible because of the sectional view in FIG. 1. Figures 2 and 3, however, show all of the compensating holes. A further bore 15 is also arranged in the wall of the cylinder 4 above the end face 16 of the percussion piston 6. The percussion piston 6 is in its working position in which it touches the tool 3. A bushing 17 surrounding the cylinder 4 is arranged in the area of the compensating bores 11, 12, 13 and 14. The bushing 17 has a groove 18 into which an eccentric lever 19 connected to an actuating element 20 engages. The bushing 17 is arranged rotatably relative to the cylinder 4.

- The compensating holes 11, 12, 13 and 14 are arranged at a distance 1 from the end face 16 of the percussion piston or percussion member 6, which is in a working position in which it touches the tool 3.

According to FIGS. 2 and 3, the bushing 17 has a control area which interacts with the compensating bores 11, 12, 13 and 14 in the wall of the cylinder 4, which extends through control bores 21, 22, 23, 24 and through wall sections 25, 26 arranged between them , 27, 28 of the socket 17 is formed. By turning the bushing 17, the compensating holes in the cylinder wall can be closed or opened one after the other by means of the wall sections and the control holes. In Fig. 2, the compensating hole 11 and in Fig. 3, the compensating holes 11 and 12 are open.

Fig. 4 shows an embodiment in which the bushing 17 is immovably anchored in the housing 1, while the cylinder 4 is rotatable within the bushing 17. For this purpose, the cylinder 4 has a longitudinal groove 29, in which the eccentric lever 19 of the actuating element 20 engages to adjust the cylinder 4. The control area of the bushing 17 also has wall sections 25, 26, 27 and 28 for closing or opening the compensation bores 11, 12, 13 and 14 arranged in the cylinder 4, as in the embodiment described above.

In an embodiment according to FIG. 5, the socket is formed in one piece with the housing 1 or the inside of the housing 1 takes over the function of the socket. In the control area, grooves 30, 31, 32 and 33 are incorporated therein, which correspond to the arrangement of the control bores 21 to 24 according to FIG. 2. The cylinder 4 is rotatably arranged in the embodiment according to FIG. 5 in the same sense as in the embodiment according to FIG. 4 by the eccentric lever 19 of the actuating element 20 engaging in a groove 34 arranged in the cylinder 4.

As a variant, the bushing 17 in an embodiment according to FIG. 6 is arranged to be displaceable in the longitudinal direction on the cylinder 4. For this purpose, the eccentric lever 19 of the actuating element 20 engages in an annular groove 35 arranged in the bushing 17. In the control area, the bushing 17 has a control opening with an obliquely running edge 36 in order to adjust the compensating bores 11, which are arranged in the cylinder wall, in the longitudinal direction. 12, 13 and 14 to be able to close in sequence.

The further embodiment shown in FIG. 7 essentially corresponds to the embodiment shown in FIG. 6. Instead of a single control opening, the embodiment according to FIG. 7 has four stepped control openings 37, 38, 39 and 40 which extend in the form of elongated holes in the longitudinal direction to the bushing 17 around the compensating bores 11, 12 arranged in the wall of the cylinder 4 , 13 and 14 to be closed in succession during an adjustment.

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The operation of the hammer drill is explained on the basis of the graph in the form of a diagram according to FIG. 8. In it show:

Si the trajectory of the drive piston;

S; the trajectory of the percussion piston under the condition that the air cushion is connected to the atmosphere via one of the compensating holes; S; i the trajectory of the percussion organ or percussion piston with two compensation holes open;

522 the movement path of the striking element with an open compensation bore which is offset in relation to the first bore along the cylinder in the direction of the striking element;

523 the movement path of the striking element with an open compensation bore which is offset with respect to the first compensation bore along the cylinder in the direction of the drive piston;

11 shows the distance between the end face of the striking member and the compensating bore, which is offset with respect to the first compensating bore along the cylinder in the direction of the striking member, 1 being less than 1;

12 the distance between the end face of the striking element and the compensating bore, which is offset with respect to the first compensating bore along the cylinder in the direction of the drive piston, lj being greater than 1;

a the point of the movement path Sii, in which the striking element covers the compensating hole, which is at a distance lt;

b the point of the movement path S22 at which the striking element opens the compensating hole which is at a distance Ii;

c the point of the movement path Si in which the drive piston opens the compensating bore which is at a distance Ii;

d the point of the movement path Sj at which the drive piston closes the compensating bore, which is located at a distance 12;

ti the time during which the striking element moving along the movement path S22 closes the compensating bore, which is located at a distance h;

t; the time during which the moving drive piston closes the compensating bore, which is at a distance of 12;

a Angle of rotation of the drive element. The percussion hammer works as follows: in the operating state of the impact, the percussion organ 6 (FIG. 1) executes a reciprocating movement in the cylinder 4 under the action of similar movements of the drive piston 5, which is connected to the percussion organ 6 via the air cushion 9 is. The striking element 6 periodically strikes the tool 3. The compensation bores 11 to 14 serve to compensate for air leakage losses from the air cushion 9 during the work of the rotary hammer.

The air cushion 9 is connected to the atmosphere via a compensating bore 11 in the cylinder 4 and via the bore 21 according to FIG. 2 in the bushing 17.

In order to prevent excessive wear of the piston seals 7 and 8, the diameter of the compensating bore 11 is made as small as possible. In order to achieve a stable function of the hammer drill when changing the path of movement of the striking member 6 while working with materials of different strength, the compensating bore 11 is made at a distance 1 from the end face 16 of the striking member 6.

This distance 1 is finally selected so that the maximum impact energy of the impact element 6 is ensured when it is displaced along the path S2 (FIG. 8).

When the piston 5 (FIG. 1) moves away from the striking element 6, a sufficiently high vacuum is formed in the air cushion 9, which ensures that the striking element 6 is lifted to the greatest possible height.

When the piston 5 moves in the direction of the striking member 6, a high pressure is generated in the air cushion 9, which ensures the movement of the striking member 6 in the direction of the tool 3 at a high speed during its collision (see the movement path S2 in FIG. 8). .

The bore 15 (FIG. 1), which lies next to the end face 16 of the striking element 6, has little effect on the work of the rotary hammer in the operating state of the impact, because the time during which it connects the air cushion 9 to the atmosphere is very short. The bore 15 ensures a reliable transition from the impact-free idle operation to the operating condition of the impact.

By turning the handle 20, the bushing 17 is rotated by an angle which is sufficient to bring bore 22 (FIG. 2) of the bushing 17 into alignment with the compensating bore 12. The rotatable arrangement of the bushing 17 allows the arrangement of the compensating bores 11, 12, 13, 14 in a plane perpendicular to the axis of the cylinder 4 in order to ensure their opening. Thus, the equalization bore 12 is opened and the air cushion 9 is connected to the atmosphere by means of two equalization bores 11 and 12. In this case, when the piston 5 (FIG. 1) moves away from the striking element 6 in the air cushion 9, a less high vacuum is generated, which ensures the stroke of the striking element 6 to a lower height than when the compensating bore 11 is open alone. When the piston 5 moves in the direction of the striking element 6, the speed of the striking element 6 decreases as it moves towards the tool 3.

In this case, the impact energy is reduced by an amount which is determined by the steepness of the movement path S21 (FIG. 8) of the impact member 6 (FIG. 1). With such a position of the compensating bore 12, a reduction in the impact energy of the impact member 6 is achieved. Any other position of the compensating bore 12 leads to a lower reduction in the impact energy of the impact member 6. If e.g. the compensating bore is at a distance Ii (FIG. 8) which is less than 1, this compensating bore is closed by this distance during the stroke of the striking element 6 (FIG. 1). During the further movement of the striking member 6 along the path S22 (FIG. 8) from point “a” to point “b”, only the compensating bore 11 (FIG. 1) is opened, which is at a distance 1 from the end face 16 of the striking member 6 is located. The movement of the striking element 6 along the path S22 (FIG. 8) during the time tj is accompanied by a higher pressure in the air cushion 9 (FIG. 1). The higher pressure in the air cushion 9 results in a faster change in the direction of movement of the striking member 6, which is given a higher speed of the collision with the tool 3 and a greater impact energy.

When another compensation bore is opened, which is at a distance from the striking element 6 that is smaller than II (FIG. 8), its influence on the reduction in the impact energy of the striking element 6 (FIG. 1) will be even smaller than the influence of the Distance Ii (Fig. 8) lying compensating hole.

If the compensating bore lies at a distance 12 which is greater than 1 (FIG. 1), it reaches the movement zone of the piston 5 along the path Si (FIG. 8) from point “d” to

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to point "c" during time t2. During the time t2 there are no air leakage losses from the air cushion 9 (FIG. 1) via the compensating hole mentioned (see S23 in FIG. 8), which consequently ensures a greater lifting height of the striking element 6 (FIG. 1) and a greater energy of its impact .

The greater the distance I2 (FIG. 8), the less the compensation hole located at this distance influences the reduction in the energy of its stroke.

The arrangement of the compensating bores along the axis of the cylinder 4 (FIG. 1) thus offers no possibility of reducing the impact energy to a required limit value, for example to zero, which reduces the control range of the impact energy of the impact member.

The further rotation of the handle 20 leads to the rotation of the bushing 17 until the bore 23 of the bushing 17 matches the compensating bore 13 (FIG. 2), two previous compensating bores 11 and 12 remaining open. This is ensured by the different position and configuration of the bores 21, 22, 23, 24 of the bushing 17 and accordingly by the position of the element which optionally opens the compensating bores 11, 12, 13, 14 of the cylinder 4 and in the form of parts 25 , 26, 27, 28 of the wall of the socket 17 is formed.

Opening the compensating bore 13, which is at a distance 1 (FIG. 1) from the end face 16 of the striking element 6, increases the air leakage losses from the air cushion 9 and accordingly reduces the impact energy of the striking element 6.

The further rotation of the handle 20 leads to the matching of all the bores 21 (FIG. 2), 22, 23, 24 of the bushing 17 with the compensating bores 11, 12, 13, 14 of the cylinder 14. Thus, all the compensating bores 11, 12, 13, 14 opened and this leads to an even greater reduction in the impact energy of the impact organ 6.

So in the arrangement of the compensating holes 11,

12.13, 14 in the plane perpendicular to the axis of the cylinder 4, the air cushion 9 during the successive opening of the compensating bores 11, 12, 13, 14 is connected to the atmosphere for a longer time during the period between two successive blows than is the case with the known rotary hammers Case is. This leads to greater air leakage losses from the air cushion 9 and to a lower reduction in the impact energy of the impact organ when the compensation bores 11, 12 are opened in succession.

13.14.

The further reduction in the impact energy when each compensating hole 11, 12, 13, 14 is opened can be brought to zero without increasing the number of compensating holes 11, 12, 13, 14, and in this way the control range of the impact energy of the impact member 6 ( Fig. 1) expand to the maximum.

In the fixed arrangement of the bushing 17 (FIG. 4) associated with the position of the compensating bores 11, 12, 13, 14 in the housing 1, the opening of the compensating bores 11, 12, 13, 14 is accomplished by rotating the cylinder 4 relative to the bushing 17 . The rotation of the cylinder 4 about its own axis is brought about by rotating the handle 20 with the aid of the eccentric lever 19, which cooperates with the groove 29 machined in the cylinder 4. The arrangement of the compensating bores 11 (FIG. 5), 12, 13, 14 in a plane perpendicular to the axis of the cylinder 4 allows the bushing 17 to be made in one piece with the housing 1. This makes it possible to simplify the construction of the hammer drill. In the housing 1, the grooves 30, 31, 32 ,. 33 and the element that optionally opens the compensating bores 11, 12, 13, 14 and is designed in the form of part of the wall of the housing 1 between the grooves 30, 31, 32, 33. With the help of the element that optionally opens the compensating bores 11, 12, 13, 14, the cylinder 4 is opened when the cylinder 4 rotates.

A variant is possible in which the bushing 17 (FIG. 6) is arranged to be longitudinally displaceable relative to the cylinder 4. This displacement is accomplished by rotating the handle 20 with the aid of the eccentric lever 19, which cooperates with the ring recess 35.

The said displacement is achieved by successively opening the compensating bores 11, 12, 13, 14 with the help of the inclined section 36 of the wall of the bushing 17 or with the aid of a series of the bores 37 (FIG. 7), 38, 39, 40 arranged on the circumference increasing size accompanied in the longitudinal direction with respect to the axis of the sleeve 17, which are provided at the location of the compensating holes 11, 12, 13, 14 of the cylinder 4.

Such a design of the bushing 17 ensures the technological simplicity of the production of the hammer drill.

Thus, the invention allows the energy of the single impact of the impact member 6 to be regulated over a wide range without changing the impact frequency. It is e.g. B. possible to compensate the performance in the destruction of the material to be processed and the performance in the removal of the destroyed small, which ensures a high drilling performance regardless of the strength of the material to be processed.

With such rotary hammers, jamming of the tool in the material to be destroyed is excluded, as a result of which the reliability of the tool and the rotary mechanism of the rotary hammer can be increased.

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3 sheets of drawings

Claims (6)

664 319 1. hammer drill with a housing (1) in which a drive member (2) and a cylinder (4) with compensating bores (11, 12, 13, 14) are arranged, in which a drive piston (5) connected to the drive member (2) ) and a percussion piston (6) which is separated from the drive piston (5) and acts on a tool (3) by means of an air cushion (9), the cylinder (4) being surrounded by a bushing (17) which has a control area to selectively open the compensating bores (11, 12, 13, 14) by means of a relative movement between the cylinder (4) and the bush (17), characterized in that the compensating bores (11, 12, 13, 14) in one for Axis of the cylinder (4) are arranged at right angles. 2. hammer drill according to claim 1, characterized in that the bushing (17) is rotatable relative to the cylinder (4) and that the control region is designed in the form of wall sections (25, 26, 27, 28) of the bushing (17). 2nd PATENT CLAIMS 3. hammer drill according to claim 1, characterized in that the bushing (17) is arranged fixedly relative to the housing (1), that the cylinder (4) is rotatable about its axis and that the control area in the form of wall sections (25, 26, 27,28) of the socket (17) is formed. 4. hammer drill according to claim 1, characterized in that the bush (17) is made in one piece with the housing (1) and that the control area in the form of a wall section of the housing (1) between control grooves (30, 31, 32, 33) arranged therein ) is trained. 5. hammer drill according to claim 1, characterized in that the bushing (17) is arranged to be longitudinally displaceable relative to the cylinder (4) and that the control region is designed in the form of an inclined wall section (36) of the bushing (17). 6. hammer drill according to claim 1, characterized in that the bushing (17) is arranged to be longitudinally displaceable relative to the cylinder (4) and that the control area in the form of a series of control bores (37, 38, 39, 40) arranged on the circumference with successively increasing Extension in the longitudinal direction to the socket (17) is formed.