Means for attaching a tool receiving sleeve to a concave slide of a machine tool

A clamping mechanism for mounting a tool holder or receiving sleeve having a cylindrical outer contour to a machine tool having a bed, the clamping mechanism comprising a slide mounted for sliding movement on the bed and having a concave surface for supporting the cylindrical outer contour of the tool holder sleeve, an apparatus for securing the slide on the bed, and a clamp assembly including a clamping bracket circumferentiallyspanning the tool holder sleeve, an arrangement for detachably securing the clamping bracket to the slide, and a threaded structure for tightening the clamping bracket around the tool holder sleeve.

The invention relates to means for attaching a sleeve receiving a tool 
holder, tool shank or the like to a so-called concave slide of a machine 
tool, i.e. a slide having a concave mounting surface. 
Concave slides of this type which are common in multiple-spindle lathes 
have, when seen transversely to the direction of guidance, a cross section 
corresponding to part of a circular ring. The face having the smaller 
radius of curvature forms a concave support surface for a tool receiving 
sleeve and is provided with a plurality of threaded bores designed as 
blind holes. The tool receiving sleeve has through bores in its wall area 
which is to rest against the concave slide. These bores are arranged in 
accordance with the threaded bores. Fastening screws are inserted into the 
through bores from the interior of the sleeve in order to secure the 
sleeve to the concave slide. To enable these fastening screws to be 
tightened, the tool receiving sleeve has second through bores located 
diagonally opposite the first through bores. These second through bores 
are designed as threaded bores and may be sealed by plug screws. This 
known construction has a number of disadvantages. In order to mount the 
tool receiving sleeve on the concave slide or dismount it again, the tool 
receiving sleeve must be empty, i.e. the tool holders, drive spindles for 
driven tools and the like cannot be inserted into the sleeve until the 
tool receiving sleeve has been mounted on the concave slide. Prior to the 
sleeve being dismounted, the tool drive spindle, tool holder or the like 
must be removed. Practical experience has also shown that the interior of 
the tool receiving sleeve is not reliably sealed against cooling medium by 
the fastening and plug screws. Cooling medium penetrating into the 
interior of the tool receiving sleeve does, however, cause corrosion 
damage. 
The object of the invention was therefore to provide a means for attaching 
a tool receiving sleeve to a concave slide, which enables a unit which is 
completely assembled, i.e. consists in a tool receiving sleeve as well as 
the parts held thereby, such as a tool drive spindle, tool holder or the 
like, to be mounted on a concave slide and dismounted therefrom. 
Accordingly, the present invention provides a clamping mechanism for 
mounting a tool holder sleeve having a cylindrical outer contour to a 
machine tool having a bed. The clamping mechanism comprises a slide 
mounted for sliding movement on the bed and having a concave surface for 
supporting the cylindrical outer contour of the tool holder sleeve, an 
apparatus for securing the slide on the bed, and a clamp assembly 
including a clamping bracket circumferentially spanning the tool holder 
sleeve, an arrangement for detachably securing the clamping bracket to the 
slide, and a threaded structure for tightening the clamping bracket around 
the tool holder sleeve. The invention therefore provides an attachment 
means similar to a pipe clamp or clip which does not require any through 
bores or other openings in the tool receiving sleeve. The tool receiving 
sleeve can therefore be mounted and dismounted when fully equipped and the 
risk of cooling medium penetrating into the interior of the tool receiving 
sleeve is eliminated. Furthermore, the tool receiving sleeve can be 
mounted on the concave slide in any axial and radial position, as 
required, since it is no longer necessary to take the pattern and position 
of threaded bores and through bores into account. The inventive solution 
also takes narrow space conditions into consideration and guarantees a 
favourable runoff of turnings or chips resulting from machining of a 
workpiece. 
In order to ensure that the attachment of the tool receiving sleeve to the 
concave slide is absolutely reliable and rigid, clamping brackets are 
recommended which have an inner contour adapted to the outer contour of 
the tool receiving sleeve or are adjustable like a tension strap. 
One end of the clamping bracket could be hinged to the concave slide and 
the other end tightened against the slide by means of a fastening screw. 
It is also possible to secure both ends of the clamping bracket to the 
concave slide by means of fastening screws. In any case, at least one of 
the fastening elements is a tightening screw mounted on one end of the 
clamping bracket while the corresponding anchoring element is designed as 
a threaded bore in the concave slide. 
The clamping bracket may be anchored to the concave slide particularly 
quickly and easily when at least one of the fastening elements is designed 
as a hook adapted to be hooked onto a projection of the concave slide, the 
hook forming one end of the clamping bracket. The clamping bracket must 
then be provided at some spot with a tightening element, for example a 
tightening screw, so that it can be tightened down. A clamping bracket 
which is divided into parts, at least two of which may be drawn together 
by a tightening screw provided therebetween, may also be advantageous for 
different reasons, for example when the tightening screw is located in a 
predetermined place on the attachment means for reasons of accessibility. 
Additional features, advantages and details of the invention are given in 
the attached claims and/or the attached drawings as well as the following 
description of several, particularly favourable embodiments of the 
inventive attachment means.

FIGS. 1 and 2 show a guide bed 10 for a concave slide 12 which is 
displaceable along the guide bed at right angles to the plane of drawing 
of FIG. 2 and is held on the guide bed by retaining blocks 14 mounted on 
the guide bed 10. Along its longitudinal edges the concave slide 12 has 
batten-like anchoring noses 16, to which the hook parts 18 of a clamping 
bracket designated as a whole as 20 may be attached. These hook parts are 
provided with threaded bores 22 while a rigid fastening member 24 has 
stepped through bores 26 at its ends. The fastening member may therefore 
be drawn towards the concave slide 12 by tightening screws 28 and 
tightened against a tool receiving sleeve 30 which may be fitted onto a 
support surface 12a of the concave slide 12. In addition, the inner 
contour 24c of the fastening member 24 is adapted to the outer contour 30a 
of the tool receiving sleeve 30, all these contours thereby appropriately 
being parts of circular-cylindrical surfaces. 
As shown in FIG. 1, a plurality of clamping brackets 20 is advantageously 
provided although it would also be conceivable to have a single clamping 
bracket which would then be correspondingly wider. 
The embodiment according to FIG. 3 differs from that of FIGS. 1 and 2 only 
in that the anchoring elements on the concave slide have the form of 
threaded bores 22'. A fastening member 24' of a clamping bracket 
designated as a whole as 20' can therefore be mounted directly onto the 
concave slide 12' by means of tightening screws 28'. This embodiment does 
not have the hook parts 18 of the first embodiment, i.e. the clamping 
bracket 20' comprises only three parts, namely the fastening member 24' 
and two tightening screws 28'. 
In the embodiment of FIG. 4, the clamping bracket 20" consists of a 
two-piece tension strap having parts 40a and 40b. Their lower ends form 
hooks 18" and so the concave slide 12 used can be the same as that of the 
embodiment according to FIGS. 1 and 2. The upper ends of the two tension 
straps form two abutments 42 and 44 for a tightening screw 46, a threaded 
bore 42a being provided in the abutment 42. 
In the embodiments of FIGS. 3 and 4, it is of course possible to use a 
plurality of clamping brackets 20' or 20" situated one behind the other 
for mounting the tool receiving sleeve 30. 
It is obvious that the tool receiving sleeve need not be 
circular-cylindrical in shape although this is normally the case.