AU640541B2 - Drilling and chiselling device - Google Patents

Abstract

The drilling and chiselling tool has a percussion mechanism and a tool holder (10) for receiving tools. Impacts from the percussion mechanism are transmitted to the tool via a ram (4). The ram (4) can be connected to a switching member (7) by means of a locking element (6), this switching member (7) being axially displaceable via an actuating means (8). The axial displacement of the switching member (7) serves to shift the ram (4) into an impact-inoperative position. <IMAGE>

Description

-I 640541

AUSTRALIA

PATENTS ACT 1990 QC0M P LETER PE R rF T P rA T TOnM FOR A STANDARD PATENT OR IG I NALI 0 0 as9 9 0s90e9 ~ame of Applicant: Se 09 9 S

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*9 HILTI AKTIENGESELLSCHAFT Vinko Pacher SHELSTON WATERS Clarence Street SYDNEY NSW 2000 "DRILLING AND CHISELLING DEVICE" .:The following statement is a full description of this invention, including the best method of performing it known to us:- 2 Drilling and Chiselling Device The invention relates to a manually guided drilling and chiselling device with striking mechanism and with a tool holder, wherein the striking mechanism imparts axial impacts through an anvil to a tool mounted in a tool holder and the anvil has at least one recess in which a looking member can be engaged by means of a switching unit that can be controlled from the outside by an actuating mechanism.

For a hammer drill with pneumatic striking mechanism, as known from DE-PS 3 627 859, inhibition of impact is attained 10 by means of hook-shaped components arranged inside a recess of the striker. The striker is thus kept in its disabled end position, unable to deliver further axial impacts to the 9 tool.

These hook-shaped component8 can be displaced in the radial 15 direction. An actuating mechanism that can be operated from the outside displays in the region of its inner periphery an excentrical deformation in the radial direction, by means of which the axial travel of a pin-shaped component can be controlled. Thus, by means of turning the actuator mechanism

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20 tangentially, an axial displacema-nt of the pin-shaped component results; the pin-shaped component subsequently controlling the movement of the hook-shaped components.

-3 As the striker can only be locked in its foremost position, it must be so designed that it can press apart radially across a tilted plane the hook-shaped, spring-loaded components that are acting upon it in the radial direction so that these are able to latch into a recess in the striker adjoining the tilted plane. Locking the striker is therefore only possible if the striker is moved in the axial direction by the striking mechanism.

The object of the invention is to create a locking mechanism by means of which the anvil can be shifted into an impact inhibited position, without the necessity of having to put the device into operation.

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1 0 According to the invention, the problem is solved by having the actuator mechanism feature a means for imparting axial movement to the switching unit.

When the actuator mechanism is being operated, an axial displacement of the switching unit takes place inside the actuator mechanism. In this manner, the anvil, joined to the switching unit through the locking member, is placed in an impact-inhibited position. Thus, this position of the anvil can be attained by the operator exclusively by manipulation of the actuator mechanism, without the necessity of pLQI: ng the device into operation.

4 It is of advantage to have the device have specifically at least one control curve, arranged on the inner side of the actuator mechanism, as the relevant means. By means of a control curve the movements of the actuator mechanism are transmitted to the switching unit.

It is preferable to design the control curve as a helical slot. By turning the actuator mechanism tangentially, an axial displacement of the switching unit can be attained. The ratio of axial displacement of the switching unit to the angle of rotation of the actuator mechanism is given by the pitch of the helix.

A further advantage of the invention is to have parts of the switching unit engage in the helical slot. This imparts exact guidance and movement to the switching unit in the operating mechanism.

It is expedient to use cams arranged in the region of the periphery as parts of the switching device. These cams match 0* 0 in their shape the cross section and the pitch of the 0 helical slot. By arranging them in the region of the periphery, their production becomes simple and economical.

The invention is especially suitable for a drilling and chiselling device with a removable tool holder. Changing the machine over from impacting operation, or switching it off, is not required. Advantages arise especially when repetitive 5 operations have to be carried out over a lengthy time period, for there is no need to check whether the machine has been set correctly.

The invention an example of Fig.1 is to be explained in greater detail by way of implementation. It is shown in: the front part of the device in partial section, with the tool holder in the unlocked position; the front part of the device in partial section, with the tool holder in the locked position.

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CC 0 10 Fig.2 The drilling and chiselling device, with its front part as shown in Fig. 1, is equipped with a guide sleeve 1. This guide sleeve 1 is supported, free to revolve, by two ball 15 bearings 2 inside a device casing 3. The shoulder stop for one of the ball bearings 2 in the device casing 3 is formed by a retaining ring 3a. In the rear portion of the guide sleeve 1 a pneumatic striking mechanism complete with impactor butt is situated, which as such is well known and 20 has not been illustrated in the drawing.

In the frontal region of the guide sleeve 1, a movable anvil 4 is situated. This anvil 4a features a toothing 4a that transmits any rotating drive or torsional couple. At the rear 6 end of the toothing 4a the anvil 4 has a slot surrounding it. The profile of the slot is preferably semi circular and it matches the profile of the locking member 6, represented in this example of application by a sphere.

A tool holder 10, designed specifically for pure rotary motion, has a recess lla at its rear zone. This recess 1la is equipped with an internal toothing that is complementary to the toothing 4a on the anvil 4. The central region of the recess in the shaft of the tool holder 11 contains the unlocked locking member 6. In the event, several locking members 6 may be considered here. It is preferred to arrange three locking members 6, mutually displaced by 120° with respect to each other, around the region of the periphery of the shaft 11 of the toolholder.

4 A radial bore 11b, in which the sphere may be moved in the radial direction, serves as the guide for the locking member 6. This bore is situated at the rear zone of the tool holder 4 o 11. The diameter of the sphere exceeds the wall thickness of the shaft 11 of the tool holder in the region of the recess 20 lla at the rear. The switching unit 7 has means of control 7b, by which the locking member 6 may be engaged radially and, on the ;ther hand, the locking member 6 may be 4* disengaged. In view of the possibility of placing several locking members 6 along the periphery, it is also possible to control several locking members 6 by the switching unit 7.

The switching unit 7 can be controlled from the outside 7 through the actuator 8.

The shape of the switching unit 7 is essentially cylindrical; it can be displaced principally in the axial direction inside the actuator mechanism 8. Minimally one cam 7a is arranged at the region of the periphery of the switching unit 7.

The actuator 8 features at its inside helical slots 9 that have an essentially rectangular cross section. The cams 7a are shaped to complement this cross section and they engage in the helical slots 9. At the beginning and at the end of each of these slots 9 there is a zone 9a of zero e** pitch. These zones 9a constitute a means of self-locking 4 against rotation of the actuator mechanism 8 with respect of sob the switching unit when axial loading is present.

o 09 Two recesses, not shown, into which a setting member can engage, are situated at the peripheral region at the rear end of the shaft 11 of the tool holder. By means of this setting wrPsmber the actuator mechanism is held in the locked or in the unlocked position, respectively.

oo Figure 2 shows the locking member 6, that is engaged in the 20 slot 5 surrounding the anvil 4. By turning the actuator mechanism 8, the switching unit 7 is displaced axially. In view of the switching unit 7 being linked through the locking member 6 with the shaft 11 of the tool holder and with the anvil 4, a rotation of the actuator mechanism 8 brings about 8 an axial displacement of all these components. The anvil 4 is pulled into its impact-inhibited end position and is held fast there. Accordingly, an operation requiring rotary movement only may thus be carried out with the drilling and chiselling device.

In its basic position, the switching unit 7 is situated at the rear end of the actuator mechanism 8. The locking member 6, of the shape of a sphere, is unlocked. Now the shaft 11 of the tool holder is inserted into the front part of the anvil 4, thus engaging both toothings, 4a, lla in each other. At the rear zone of the actuator mechanism 8, inside an extended circular recess 17 a separator disc 16 is situated that is kept in position by retaining rings 16a inside the recess 17.

The separator disc 16 has a collar stop 16b pressing O 15 against the front side of the guide sleeve 1.

Turning the actuator mechanism 8 initially in the tangential direction causes the switching unit 7 to rotate together with the actuator mechanism 8. The position of the switching unit 7 reached thereby corresponds at the same time to the 20 locked position of the locking member 6. The looking member 0 6, also of the shape of a sphere, engages in a recess surrounding the anvil 4.

00 e *0 In the zone of zero pitch at the beginning of the helical slot 9, a recess 12, in which a rotation securing member 13 in the switching unit 7 can engage, is situated at the 9 helical base of the slot. The rotation securing member 13 is a spring-loaded sphere, situated in a recess 14 in the cam 7a of the switching unit 7. The recess 14 is arranged in the radial direction. The sphere is guided inside this recess 14 and presses against a spring 15 placed inside the recess 14 and supported by the base of the recess 14. In the course of further rotation by the actuator mechanism 8 the sphere is squeezed out from the recess 12 at the base of the helical slot 9 and pressed into the recess 14 situated at the cam.

A further rotation of the actuator mechanism 8 will cause the S* cam 7a to leave the zone of zero pitch 9a of the slot 9 and to reach the helically shaped region. This implies a relative displacement in the axial direction of the switching unit 7 with respect to the actuator mechanism 8.

At the end of the helical region there is again a zone 9a of zero pitch of the slot 9, with the aim of again vouchsafing self-locking against rotation of the actuator mechanism 8.

S Once this position is reached, the anvil 4 is locked in its

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S impact inhibited end position. A rotary motion created by the drive transmitted by the anvil 4, is thus transmitted by the anvil 4 through the shaft 11 of the tool holder to a tool fastened in the tool holder Unlocking the anvil 4 is accomplished by reversing the sequence described above.

Claims (3)

1. A manually operated drilling and chipping tool comprising a holder for a tool bit, said drilling and chipping tool arranged to operate as a rotary drill with only rotary movement of the holder or as a hammer drill with combined rotary and percussive movement of the holder, a tool housing having a leading end with said holder mounted in the leading end, an axially extending anvil located within said housing and arranged to deliver axially directed blows to said holder, said anvil has at least one recess therein, a locking element is displaceable into the recess in said anvil by a shifting member, an actuation member mounted on said housing and accessible on the leading end thereof and in engagement with said shifting member, wherein said actuating member includes tneans for producing axial movement of said shifting member within said housing.

2. A manually operated drilling and chipping tool, as 0: set forth in claim 1, wherein said means comprises at least one control cam or curve located on an inside surface of the actuation member.

3. A manually operated drilling and chipping tool, as set forth in claim 2, wherein said control cam or curve is a helically shaped groove. 3. A manually operated drilling and chipping tool, as set forth in claim 3, wherein said shifting member has at leat one part thereon engageable within the helically shaped groove. A manually operated drilling and chipping tool, as set forth in claim 4, werein the at least one part of the shifting member comprises cams located in an outer circumferentially extending region of said shifting memeber. DATED this 7th day of May 1993 HILTI AKTIENGESELLSCHAFT Attorney: PETER HEATHCOTE Fellow Institute of Patent Attorneys of Australia of SHELSTON WATERS 11 ABSTRACT The drilling and chiselling device features a striking mechanism and a tool holder (10) to accommodate tools. Impacts are transmitted from the striking mechanism to the tool through an anvil By means of a locking member the anvil can be linked to a switching unit such that this switching unit can be axially displaced through the agency of an actuator mechanism. The axial displacement of the switching unit serves the purpose of placing the *Oe anvil into an impact-inhibited position. 0* 6 0 *0 o 0 S