WO1998032562B1

WO1998032562B1 - Hydraulic precision mandrel

Info

Publication number: WO1998032562B1
Application number: PCT/SE1997/002195
Authority: WO
Filing date: 1997-12-19
Publication date: 1999-02-18

Abstract

A hydraulic precision mandrel for use in rotary machine tools and comprising a transition part (1) and a clamp body (3) which is fixedly connected thereto, onto which clamp body one or more tools can be slided and can be secured, and in which the clamp body (3) is formed as a hydraulic clamp bushing having a radially outwards expandable outer wall (9) and, radially inside said outer wall (9), an all around extending gap (10) which is filled with a hydraulic pressure medium (12), and in which the clamp body (3) is formed with an axial, central bore (13) provided in the clamp body (3), one or more cross channels (14) opening in the pressure medium gap (10), a piston (15) defining a pressure medium chamber (16) which is filled with pressure medium (12) and which is located at or adjacent the inner end of the clamp body bore (13), and a pusher means (17), for instance a threaded pusher piston which is within reach through the free end of the clamp body, for instance by means of a wrench (19) and which is adapted to move the piston inwards or outwards in the mandrel body bore (13) for pressurization and pressure releasing, respectively, of the pressure medium in the all around extending pressure medium gap (10). The mandrel comprises a rubber spring (20, 22) for resiliently pressing and radially straightening up the tool or tools (4) against a radial flange (5) of the transition part.

Claims

8 AMENDED CLAIMS[received by the International Bureau on 28 May 1998 (28.05.98); original claims 1-7 replaced by amended claims 1-7 (2 pages)]

1 . Mandrel apparatus for making it possible to clamp connecting tools (4) in rotary machine tools and comprising an integral unit formed with means for mounting of the apparatus in the machine tool, a transition part (1 ) and a clamp body (3) for clamp connecting said tool (4), characterized

- in that the apparatus is formed as a mandrel, in which the clamp body (3) is formed as a hydraulic clamp bushing having a thin, smooth outer wall (9) onto the outer surface of which one or more tools can be slided and can be secured, and an inner solid mandrel body (1 1 ), and a gap (1 0) provided between said thin outer wall (9) and the mandrel body ( 1 1 ), which gap is filled with a hydraulic pressure medium ( 1 2) which, when pressurized, makes the outer wall (9) expand radially outwards thereby clamp connecting said tool or tools (4),

- in that the mandrel body (1 1 ) at the interior thereof is formed with means ( 1 5, 1 7) for pressurization of the pressure medium ( 1 2) in the pressure medium gap (1 0) and comprising an axial, central bore (1 3) in the mandrel body ( 1 1 ), which can be reached from the free end of the apparatus and which contains a pressure piston (1 5) defining a pressure medium chamber (1 6) which is filled with pressure medium (1 2), and which communicates which the pressure medium gap ( 10) of the clamp body (3) over one or more cross channels (14) at a place close to the mandrel body bore (1 3),

- and in that the pressure piston (1 5) is arranged for being actuated by a pusher means (1 7) which can be reached from outside the apparatus through the free end of the clamp body (3), and which is arranged for displacing the piston (1 5) inwards or outwards in the mandrel body bore (1 3) for pressurizing and for releasing the pressure, respectively, of the pressure medium in the all around extending pressure medium gap (10).

2. Mandrel apparatus according to claim 1 , characterized in that the pusher means is a rotatable piston (1 5, 1 7) which is threaded and engages inner threads ( 1 8) of the mandrel body bore (1 3) and which is formed with a coupling bore for engagement of a wrench (1 9) adapted to be introduced through the end of mandrel body bore (1 3) and used for tightening an untightening, respectively, of the piston (1 5, 1 7).

3. Mandrel apparatus according to claim 1 or 2, characterized in that the transition part ( 1 ) has a radial flange (5) at the connection end for the clamp body (3), and in that the mandrel, at the free end of the clamp body (3), has a pressure ring (20) adapted to provide a press engagement and to straighten up the tool or tools (4) against the flange (5) before the tools are clamp connected by pressurization of the pressure medium gap (10) of the clamp body (3).

4. Mandrel apparatus according to claim 3, characterized in that the pressure ring (20) is secured to the mandrel by means of a central tap screw (21 ) which is connected to the threaded bore ( 1 8) of the clamp body (1 1 ) by means of screw threads.

5. Mandrel apparatus according to claim 3, characterized in that the pressure ring (20) is secured to the mandrel by means of a pair of screws extending through the tool or tools (4), which screws are threaded into the transition part (1 ).

6. Mandrel apparatus according to claim 3, 4 or 5, characterized in that the tool (4), or the tool located closest to the transition part ( 1 ) is formed with a pair of follower pins (7) arranged to engage corresponding follower bores (6) of the transition part.

7. Mandrel apparatus according to any of claims 3 - 6, characterized in that the pressure ring (20) is formed with a rubber ring (22) which is partly embedded in said pressure ring (20) and which acts as a rubber spring when the tool or tools is/are pressed against the flange (5) of the transition part (1 ) .