WO2006105951A1

WO2006105951A1 - Spindle unit for a boring machine

Info

Publication number: WO2006105951A1
Application number: PCT/EP2006/003101
Authority: WO
Inventors: Gabriele Piccolo
Original assignee: Hpt Sinergy S.R.L.
Priority date: 2005-04-07
Filing date: 2006-04-05
Publication date: 2006-10-12
Also published as: ITVE20050019A1

Abstract

A spindle unit for a boring machine, characterised by comprising, in Combination: a rototranslating member (6, 8; 32, 36) for supporting the tool, a support and guide head (2) for said rototranslating member (6, 8; 32, 36), means (10; 30, 34) for supporting and guiding the movements of said rototranslating member (6, 8; 32, 36) relative to said head (2), at least one motor (14) axially rigid with said rototranslating member (6, 8; 32, 36) for its rotation, means (24, 28) for axially translating said rototranslating member relative to said head (2), translation guide means, interposed between said rototranslating member (6, 8; 32, 36) and said head (2).

Description

SPINDLE UNIT FOR A BORING MACHINE

The present invention relates to a spindle unit for a boring machine. Boring machines with a rotary spindle are known, within which a tubular toolholder structure is disposed axially slidable relative to the spindle and rotating with it. The tubular structure is supported and guided within the spindle by pairs of slidable supports spaced apart in the direction of the spindle.

In these known machines the rotational motion of the tubular toolholder structure is obtained by a motor rigid with the machine structure and with speed reduction members interposed between this and the toolholder structure, whereas its axial translational motion is obtained by splined coupling systems, which ensure that they rotate together.

A drawback of these known machines is that the greater their performance, in the sense of the amount which the tubular toolholder structure penetrates into the workpiece, the greater has to be the axial length of this structure. The result is that with machine performance increase, the torsional rigidity of said tubular toolholder structure decreases and the overall machine dimensions increase.

Another drawback is that the presence of inevitable coupling clearances between sliding members and rotating members results in vibration, noise, wear and machining inaccuracies.

All these drawbacks are overcome according to the invention by a spindle unit for boring machines as claimed in claim 1.

Two preferred embodiments of the present invention are described hereinafter with reference to the accompanying drawings, in which: Figure 1 is a schematic longitudinal section through a spindle unit of the invention taken on the line l-l of Figure 2, Figure 2 is a cross-section therethrough on the line H-Il of Figure 1 , and Figure 3 shows a different embodiment thereof in the same view as Figure 1.

As can be seen from the figures, the boring machine spindle unit according to the invention comprises a spindle head 2, which is fixed by traditional systems to a boring machine.

The (rear) end of the spindle head 2 is open, while its other (front) end is provided with a headpiece 4 supporting a spindle 6, which in its turn supports and guides a tubular toolholder structure 8 is applied.

Rolling bearings 10 are applied to the headpiece 4 to ensure low friction between the head 2 and the spindle 6.

Within the head 2 the tubular toolholder structure 8 is secured to the rotor 13 of an electric motor 14, preferably of direct drive type, the stator 16 of which is fixed to the inner cylindrical wall of the casing 18.

Depending on requirements, the tubular toolholder structure 8 can be made in a single piece or in several parts connected together by joints.

Alternatively, an electric motor and speed reduction gear or an electric motor and gearbox can be applied to the tubular structure 8.

The casing 18 is provided with two pairs of shoes 20, by which it is slidably engaged in two parallel guide rails 22 disposed longitudinally within the upper inner wall of the spindle head 2.

A threaded shaft 24 is disposed between the two parallel rails 22, supported by supports fixed to the upper inner wall of the spindle head 2 and connected at its rear end (on the left in the drawings) to an electric motor 26, also fixed to the spindle head 2. The threaded shaft 24 is engaged in a threaded bush 28 fixed to the casing 18. As an alternative to the mover member formed by the threaded shaft 24 and threaded bush 28, any other type of actuator, for example a linear motor, can be advantageously used.

The operation of the spindle unit of the invention will be immediately apparent from the aforegoing description: the electric motor 26 which drives the threaded shaft 24 causes the tubular toolholder structure 8 to move axially, while still able to rotate supported by the spindle 6.

Whenever a greater torque is required at the tubular toolholder structure 8, instead of one motor, two motors 14 spaced apart axially but both housed within the casing 18 can be coupled to it.

From the aforegoing it is apparent that the machine tool spindle unit of the invention is particularly advantageous, in that it eliminates all drawbacks present jointly and separately in traditional spindle units, and in particular:

- it considerably reduces the axial length of the tubular toolholder structure 8, - it eliminates coupling clearances between said structure 8 and its drive,

- it increases the torsional rigidity of the structure.

In the embodiment shown in Figure 3, the headpiece 4 of the spindle head 2 supports a fixed support 30 for guiding a tubular spindle carrier structure 32.

This fixed support 30 is essentially of annular shape and is provided on its inner surface with a rolling bearing or a hydrostatic bearing 34 ensuring low friction between the support 30 and the tubular spindle carrier structure 32.

In the interior of the head 2 the tubular spindle carrier structure 32 extends into a widened portion 18 forming the casing of the electric motor 14, of which the stator 16 is fixed to the inner cylindrical wall of the casing 18 and the rotor 13 is fixed to the shaft 36 of a toolholder spindle, itself supported on the frame 18 and on the tubular spindle carrier structure 32 via rolling bearings 38. Again in this case the casing 18 of the electric motor 14 is slidabie within the spindle head 2 in the manner already described in relation to the preceding embodiment.

Claims

C L A I M S

1. A spindle unit for a boring machine, characterised by comprising, in combination:

- a rototranslating member (6, 8; 32, 36) for supporting the tool, - a support and guide head (2) for said rototranslating member (6, 8; 32, 36),

- means (10; 30, 34) for supporting and guiding the movements of said rototranslating member (6, 8; 32, 36) relative to said head (2),

- at least one motor (14) axially rigid with said rototranslating member (6, 8; 32, 36) for its rotation, - means (24, 28) for axially translating said rototranslating member relative to said head (2),

- translation guide means, interposed between said rototranslating member (6, 8; 32, 36) and said head (2).

2. A unit as claimed in claim 1 , characterised in that the rototranslating member (6, 8) comprises a spindle (6) rotationally supported by said head (2), and a tubular toolholder structure (8) rigidly rotatable with said spindle (6) but axially slidable relative thereto.

3. A unit as claimed in claim 2, characterised in that the spindle (2) presents a front portion supporting said rototranslating unit (6, 8) in an axially slidable and rotatable manner, and a front portion (18) housing said motor (14).

4. A unit as claimed in claim 3, characterised by comprising rolling bearings (10) interposed between the front portion of said spindle head (2) and said spindle (6).

5. A unit as claimed in claim 3, characterised in that the frame (18) of said motor (14) is provided with shoes (20) cooperating with guide rails (22) rigid with said spindle head (2).

6. A unit as claimed in claim 5, characterised in that the frame (18) of said motor (14) comprises pairs of shoes (20) aligned along the longitudinal axis of said rototranslating unit (6, 8) and cooperating with guide rails (22) rigid with said spindle head (2).

7. A unit as claimed in claim 1 , characterised by comprising a threaded shaft (24) with threaded bush (28) for longitudinally moving said rototranslating unit (6, 8; 32, 36) along said spindle head (2).

8. A unit as claimed in claim 1 , characterised by comprising a linear motor interposed between said rototranslating member (6, 8; 32, 36) and said spindle head (2).

9. A unit as claimed in claim 1, characterised in that at least one direct drive motor is associated with the rotating part (8, 36) of said rototranslating member.

10. A unit as claimed in claim 1 , characterised in that a motor and a speed reduction gear are associated with the rotating part (8, 36) of said rototranslating member.

11. A unit as claimed in claim 1 , characterised in that a motor and a gearbox are associated with the rotating part (8, 36) of said rototranslating member.

12. A unit as claimed in claim 1, characterised in that the rotating part (8, 36) of said rototranslating member is constructed in several parts connected together by joints.

13. A unit as claimed in claim 1 , characterised in that the rototranslating member comprises:

- a toolholder spindle (36),

- a tubular support structure (32) for said spindle (36), which is translationally rigid therewith but is free to rotate, - at least one motor (14) housed inside said spindle head (2), and having its rotor (13) mechanically secured to said spindle (36) and its stator (16) mechanically secured to said tubular structure (32).

14. A unit as claimed in claim 13, characterised in that the tubular spindle carrier structure (32) presents a front portion which slides within the support means (30) provided in the spindle head (2), and a rear portion (18) which always remains housed within the spindle head (2) and has a greater transverse dimension, said rear portion housing said motor (14).

15. A unit as claimed in claim 13, characterised in that said support and guide means consist of an annular support (30) which is provided with a hydrostatic bearing (34) on that surface cooperating with said tubular structure (32).

16. A unit as claimed in claim 13, characterised in that said support and guide means consist of an annular support (30) which is provided with a bush with rolling elements on that surface cooperating with said tubular structure (32).

17. A unit as claimed in claim 13, characterised in that the rear portion (18) of said tubular spindle carrier structure (32) forms the casing of said electric motor (14).