GB2152410A

GB2152410A - Drilling and boring tool

Info

Publication number: GB2152410A
Application number: GB08430089A
Authority: GB
Inventors: Gunther Bach; Gerhard Scheer
Original assignee: Komet Praezisionswerkzeuge Robert Breuning GmbH
Current assignee: Komet Praezisionswerkzeuge Robert Breuning GmbH
Priority date: 1984-01-14
Filing date: 1984-11-28
Publication date: 1985-08-07
Also published as: IT8519077A0; IT1199630B; CH664312A5; FR2558088A1; DE8401019U1; GB8430089D0; JPS60167702A; GB2152410B; JPH0379123B2; IT8519077A1; FR2558088B1

Abstract

A drilling and boring tool has a housing (3) which is provided at the front end of a holder shaft (1), a slide member (4) which is radially displaceable in the housing (3) with respect to the axis (A) of the holder shaft (1) by means of a screwthreaded spindle (5) and which bears against the inside of a cover plate (7) closing the housing (B) in a forward direction. The slide member (4) has a cylindrical spigot (9) which projects through an opening (8) in the cover plate (7). The shank portion (10a) of the tool receives the spigot (9) in a fitting bore (11), and bears with an annular surface (12) against the face (7b) of the plate (7). Two diametrically oppositely disposed, radially extending female screwthreads (13,14) each have a clamping screw (15,16) provided with a conical projection (15a) or a conical depression (16a) which engages a clamping pin (8) radially displaceable in a transverse bore (17) in the spigot (9). The clamping pin has a conical depression (19a) or a conical projection (19b), respectively co-operating with the conical projection (15a) or depressions (16a) of the clamping screw (15,16). The axis (A1) of the female screwthreads (13,14) is further from the annular surface (12) than the axis (A2) of the transverse bore (17) is from the front face (7b), so that when one of the clamping screws (15,16) is tightened, it acts on the clamping pin (18) to press the annular surface (12) and the front face (7b) towards each other. <IMAGE>

Description

SPECIFICATION Drilling and boring tool The invention relates to a drilling and boring tool having a housing which is provided at the front end of a holder shaft, a slide member which is displaceable in the housing radially with respect to the axis of the holder shaft by means of a screwthreaded spindle and which bears against the inside of a cover plate closing the housing in a forward direction and which has a cylindrical spigot which projects forwardly through an opening in the cover plate, for receiving a tool shank portions, wherein a screw arrangement which acts radially with respect to the axis of the holder shaft is provided for clamping the tool shank portion.

In a known drilling and boring tool of that kind (Swiss patent specification No 593,749), the cylindrical spigot has a central bore into which the shank portion of the tool can be fitted. The shank portion of the tool can be clamped fast in the bore in the cylindrical spigot by means of two radially acting screws which are arranged at displaced positions relative to each other in the axial direction. That kind of connection is unstable and suffers from inaccuracies. The same also applies in regard to the connection between the slide member and the housing in which it is guided. Any play between the slide member and the housing has an effect on the accuracy of operation. Here too the connection between the slide member and the housing is less stable and strong so that the known tool can only be used for very fine machining operations.

The invention is based on the problem of providing a drilling and boring tool of the kind set forth in the opening part of this specification, wherein there is a very stable connection which is easy to release and re-make between the tool and the housing so that the tool can be used for carrying out coarse as well as very fine machining operations.

In accordance with the invention, that is achieved in that the cylindrical spigot is in the form of a fitting spigot and the shank portion of the tool receives the fitting spigot in a fitting bore, and bears with an annular surface around the fitting bore against the face of the plane-parallel cover plate, that the shank portion of the tool, in the region of the fitting bore, has two diametrically oppositely disposed, radially extending female screwthreads each having a clamping screw provided with a conical projection or a conical depression, that a clamping pin is radially displaceable in a transverse bore in the fitting spigot, the clamping pin being provided at each end with a conical depression or a conical projection cooperating with the conical projection or depression of the respective clamping screw, and that the spacing of the axis of the female screwthreads from the annular surface is somewhat larger than the spacing of the axis of the transverse bore from the front face, so that when one of the clamping screws is tightened, it acts on the clamping pin to press the annular surface and the front face towards each other.

Therefore, the invention is based on the idea of arranging that the shank portion of the tool bears with an annular surface which is comparatively large in diameter, directly against the front face of the cover plate and, after the fine setting has been carried out, is pressed against the front face of the cover plate by tightening one of the clamping screws. When the annular surface is pressed against the face of the cover plate in that way the slide member is at the same time pressed against the inside of the cover plate. That therefore forms a direct connection between the shank portion of the tool and the cover plate which is fixedly connected to the housing. That connection can be easily released and re-made by actuating one of the two clamping screws.By virtue of the direct connection between the shank portion of the tool and the cover plate and by virtue of the shank portion of the tool being supported on a comparatively wide base surface, the arrangement provides an extremely stable and rigid connection between the holder and the shank portion of the tool, which permits the drilling and boring tool according to the invention also to be used to carry out heavy operations in which high machining forces occur. Thus, the tool according to the invention can be used for drilling operations in solid material and also for heavy boring operations, and a very fine machining operation, with a high degree of accuracy, can then follow without a change of tool.

In particular, the tool according to the invention can also be used to produce accurate bores which are larger than the nominal diameter of the drill used.

An advantageous embodiment of the invention provides that one clamping screw has a conical projection and the other clamping screw has a conical depression and that accordingly, at its one end, the clamping pin is provided with a conical depression while at its other end it has a conical projection.

The invention is described in greater detail hereinafter with reference to an embodiment as illustrated in the drawing.

The drawing shows a side view, partly in axial section, of the drilling and boring tool.

The holder 1 has any shaft or shank 2 which is suitable for mounting to the spindle of a machine tool and which carries a housing 3 at its front end.

The slide member 4 is displaceable radially with respect to the axis of the holder shaft 2, in the housing 3. For the purposes of fine adjustment of the slide member 4 the arrangement has a screw spindle 5 which is axially immovably but rotatably mounted in the housing 3 and engages with a female screwthread 6 in the slide member 4. Further details of the construction and the mounting of the screw spindle 5 are described in Swiss patent specification No 593 749.

The housing 3 is closed forwardly by a cover plate 7 which is fixedly connected to the housing 3. The slide member 4 bears against the inside 7a of the cover plate 7. The cover plate 7 also has an opening 8 for a cylindrical fitting spigot 9 which is formed in one piece with the slide member 4, and passes through the cover plate 7. The tool 10, being for example a drilling tool, a boriing bar or a multipurpose tol, has a shank portion 1 0a having a central fitting bore 11 which fits the spigot 9. The shank portion 1 0a of the tool extends as far as the front face 7b of the cover plate 7 which is formed as a plane-parallel plate. The shank portion 10a of the tool bears against the face 7b with an annular surface 12 which is disposed around the bore 11.

In addition, in the region of the bore 11, the shank portion 10a of the tool has two diametrically oppositely disposed radially extending female screwthreads 13 and 14 each of which serves to receive a respective clamping screw 15, 16. The axis of the two screwthreads 13 and 14 is denoted by Al. One clamping screw 15 is provided with a conical projection 15a while the other clamping screw 16 has a conical depression 16a.

The sprigot 9 has a transverse bore 17 in which a clamping pin 18 is radially displaceably mounted. At its one end which is towards the clamping screw 15, the clamping pin 18 has a conical depression 19a while at its other end it has a conical projection 19b, wherein the apex angles of the conical depression 19a and the conical projection 19b correspond to the apex angles of the conical projections 15a and the conical depression 16a. The axis of the transverse bore is denoted by A2.

The arrangement is such that the spacing a1 of the axis Al of the female screwthreads 13 and 14from the annular surface 12 is somewhat larger than the spacing a2 of the axis A2 of the transverse bore 17 from the front face 7b. When one of the clamping screws, preferably the clamping screw 15, is tightened, the annular surface 12 is pressed firmly against the face 7b while at the same time the slide member 14 is pressed against the inside 7a of the cover plate 7. That therefore provides a direct and strong connection between the shank portion 1 0a of the tool and the cover plate 7. As the latter is fixedly connected to the housing 3, that provides an extremely strong and stable connection between the tool 10 and the holder 1.That connection can be easily released for radial fine adjustment by releasing only one of the clamping screws, whereupon fine adjustment may be made by means of the screwthreaded spindle 5. The released clamping screw is then re-tightened. As, in that connection, only axial forces act on the shank portion 10a of the tool and the spigot 9, the set position of the tool is not altered in the radial direction when the clamping screw 15 is tightened.

The tool 10 shown in the drawing has two main cutter plates 20 which together have a working diameter D of for example 30 mm. The tool 10 has also an additional cutting plate 21 which is disposed at a displaced position in the axial direction towards the shank portion 10a of the tool, with respect to the two main cutting plates 20. The additional cutting plate 21 is so arranged that its effective cutting edge 21 a has a somewhat larger working diameter of for example 30.4 mm. The precise working diameter which is actually required can be set by means of the spindle 5. When using a tool 10 of that kind, in one working operation, it is possible to produce a bore of initially 30 mm by means of the main cutting plates 2O, which can then be finely bored out to a diameter of 30.4 mm by the following additional cutting plate 21. Previously, such a machining operation required two working operations with two machine spindles or two working operations with one machine spindle and an intermediate change of tool.

With the novel drilling and boring tool however, it is also possible to produce and finely machine a somewhat larger bore, using the same tool 10. For that purpose, the slide member 4 is set by means of the screw spindle 5 in such a way that for example the axis of the tool 10 is displaced by 0.8 mm with respect to the axis A of the holder shaft. When a tool 10 is set in that way, it is possible to drill a bore of 31.6 mm into solid material, which in turn is finely bored out to a diameter of 32 mm by the following additional cutting plate 21.

Claims

1. A drilling and boring tool having a housing which is provided at the front end of a holder shaft, a slide member which is displaceable in the housing radially with respect to the axis of the holder shaft by means of a screwthreaded spindle and which bears against the inside of a cover plate closing the housing in a forward direction and which has a cylindricl spigot which projects forwardly through an opening in the cover plate, for receiving a tool shank portion, wherein a screw arrangement which acts radially with respect to the axis of the holder shaft is provided for clamping the tool shank portion, characterised in that the cylindrical spigot is in the form of a fitting spigot (9) and the shank portion (1 0a) of the tool receives the fitting spigot (9) in a fitting bore (11), and bears with an annular surface (12) around the fitting bore (11) against the face (7b) of the plane-parallel cover plate (7), that the shank portion (10a) of the tool, in the region of the fitting bore (11), has two diametrically oppositely disposed, radially extending female screwthreads (13, 14) each having a clamping screw (15, 16) provided with a conical projection (15a) or a conical depression (16a), that a clamping pin (8) is radially displaceable in a transverse bore (17) in the fitting spigot (9), the clamping pin being provided at each end with a conical depression (19a) or a conical projection (19b) cooperating with the conical projection (15a) or depression (16a) of the respective clamping screws (15, 16), and that the spacing (a1) of the axis (Al) of the female screwthreads (13, 14)from the annular surface (12) is somewhat larger than the spacing (a2) of the axis (A2) of the transverse bore (17) from the front face (7b), so that when one of the clamping screws (15, 16) is tightened, it acts on the clamping pin (18) to press the annular surface (12) and the front face (7b) towards each other.

2. Atool according to claim 1 characterised in that the one clamping screw (15) has a conical projection (15a) and the other clamping screw (16) has a conical depression (16a) and that correspondingly the clamping pin (19) is provided at its one end with a conical depression (19a) and at its other end with a conical projection (19b).

3. Atool according to claim 1 or claim 2 characterised in that an additional cutting plate (21) is provided on a drilling tool (10) in addition to the main cutting plates (20) for drilling purposes, the additional cutting plate being displaced in the axial direction rearwardly towards the shank portion (1 0a) of the tool with respect to the main cutting plates (20) and the effective cutting edge (21) thereof being of somewhat larger working diameter (D1) than the main cutting plates (20) and extending is the direction of movement of the slide member (4).

4. A drilling and boring tool substantially as described hereinbefore with reference to the accompanying drawing.