Machine tool and chucking attachment and tool head therefor

A machine tool has chuck means defining a geometric axis for holding a workpiece and turret means rotatable about an axis of rotation. The turret means includes at least one end surface, a peripheral surface and first fastening means distributed along a circle within a plane extending normally to the axis of the rotation and being adapted to fasten a tool by means of its fastening surface. At least one tool chucking attachment has a fastening surface to be fastened by the first fastening means instead of a tool head. The tool chucking attachment includes at least one second fastening means having fast-locking means for receiving the fastening surface of a tool head.

The invention relates to a machine tool, and in particular to a turning 
machine for machining workpieces by means of at least one of a plurality 
of headed tools having a fastening surface on the tool head and to a 
chucking attachment and a tool head therefor. 
BACKGROUND OF THE INVENTION 
For the purposes of the present invention, "fastening means" are 
"connections", "chucking attachments" are "tool head holders" and "tool 
heads" are "tool holders". 
Many turning machines which have a fast-action lock for rapid change of 
tools are available on the market. Many different designs have also been 
proposed for this purpose, of which one designated as VDI chucking system 
has become particularly widespread. The term "turning machine" is now 
understood as meaning processing machine in which there is a relative 
rotation of workpiece and/or tool to achieve machining. It is known per se 
that the tools can e arranged on a turret, so that change can be effected 
more rapidly. The disadvantage of all these designs, however, is that the 
number of tools to be connected is generally limited. 
PRIOR ART 
Although German Auslegeschrift 2,341,999 discloses a multiple tool holder, 
this is intended for only a very limited field of use, namely for 
plunge-cutting of circular grooves with the aid of two tools which 
essentially point in the same direction and are intended to act on a 
workpiece in succession. 
U.S. Pat. No. Re 29,612 describes a turret on whose peripheral surface tool 
holders can be fastened by means of a plurality of screws (generally 
four). Here, it is not possible either to remove the tool holders rapidly 
or to mount a number of tools over and above the number of fastening 
points for tool holders. 
For many tools, a tool head is provided which is either fastened to the 
tool or detachably connected to it, and which is fastened to the tool 
holder. 
German Offenlegungsschrift 3,430,380 describes an interchangeable tool head 
having a plurality of chucks for detachable fastening of a plurality of 
tools. However, the chucks are unsuitable for rapid changing of tools 
because the correct position of the tool and its projecting length must be 
adjusted by a tedious procedure in the chuck itself, which is 
correspondingly labor-intensive. Particularly for NC machines which have 
numerical control for automatic machining, tools having predetermined 
masses and dimensions are therefore generally used, as well as the stated 
fast-action locks. German Offenlegungsschrift 3,202,042 describes a 
similar situation. The tool head there is inserted directly into the 
turret head and has a chuck for holding a tool. 
Nevertheless, in many cases a "0" production pass is necessary to permit 
the correct tool setting or machine setting for a special workpiece. 
Finally, FR-A-2 486 848 discloses that a turret head can be provided with 
reception holes running continuously from one face to the other for 
fastening tools. However, it is only possible to fasten a tool alternately 
at one end face or the other but not to equip both end faces 
simultaneously with tools, for example to machine two opposite end faces 
of a groove immediately after one another without change-over time. 
Another problem in machine tools is the precision which is generally 
present but not very great. If, however, it is desired to machine pieces 
with relatively high dimensional stability, special machines which are 
expensive to acquire and are generally little used are required. 
Alternatively, such deficiencies can be eliminated only by expensive 
computer programs which cannot be used for many NC machines. 
OBJECT AND STATEMENT OF THE INVENTION 
It is therefore the object of the invention to improve a machine tool of 
the type stated at the outset in such a way that, on the one hand, tool 
change can be carried out rapidly, and either a larger number of tools can 
be kept in readiness, avoiding a long change-over time and furthermore 
machining time, and/or to increase the machining precision--even in 
existing machine tools--without higher capital costs being necessary for 
this purpose. 
This object is achieved, according to the invention, by the following 
features: 
chuck means for defining a geometric access for holding a workpiece; 
turret means rotatable about an axis of rotation, said turret means 
including 
at least one end surface, and 
a peripheral surface, 
first fastening means distributed along a circle within a plane extending 
normally to said axis of rotation and being adapted to fasten one of a 
plurality of headed tools by means of its fastening surface; 
at least one tool chucking attachment having a fastening surface to be 
fastened by said first fastening means instead of a tool, said tool 
chucking attachment including 
at least one second fastening means having fast-locking means for receiving 
the fastening surface of said tool head. 
These features allow each chucking attachment coordinated with a fastening 
means to be adjusted individually with respect to the fastening means and 
the turret head acid so that its individual fastening means, namely the 
further fastening means of the chucking attachment, lies precisely on a 
circle through which all tools pass on rotation of the turret head. This 
means that its geometric dimensions with respect to the machining axis (5, 
5') can each be positioned at an exactly defined point. The chucking 
attachment thus serves as an adapter between a conventional turret head 
and a conventional tool head and compensates for any lack of precision of 
the turret head. In the simplest case, adjustment can be carried out with 
the aid of shims; however, it is also possible to adopt an arrangement 
such that the fastening parts for fastening to the turret head, which are 
present on the chucking attachment, are equipped with adjustment cams to 
permit exact alignment. The entire chucking attachment can of course also 
be produced individually, in particular according to the following 
features: 
an elongated body of at least approximately prismatic shape, the body 
having first and second ends in a sufficient distance from each other to 
extend said first end beyond the peripheral surface of a tool turret when 
mounted on it, said body comprising 
a support surface portion to be applied against the end surface of the tool 
turret, and 
a further surface portion facing away from said support surface portion, 
first and second tool bearing surface portions within the region of said 
first end of said elongated body, said tool bearing surface portions 
facing away from each other and extending parallel to or flush with said 
support surface portion, 
a peg-like extension projecting at right angles from said support surface 
portion within the region of said second end, and having at least one 
fastening surface to be inserted into one of said tool receiving holes; 
first and second tool holding means on said first and second tool bearing 
surface portions, respectively, to connect a headed tool onto each of said 
tool bearing surface portions, said tool holding means each including 
fast-locking means; and 
at least one means forming a fluid line on said elongated body, said means 
extending from the region of said first end to the region of said second 
end, and including line coupling means within the region of said second 
end. 
Said fluid line is a lubricating line. 
Said fluid line comprises a feed section and a return section. 
The chucking attachment further comprises fluidic drive means on said fluid 
line. 
Said fluidic drive means are to actuate said fast-locking means. 
Said fluid line comprises at least one control valve for controlling the 
rate of fluid flow. 
The above advantages also apply to the following embodiment where the 
essential feature is that power transmission is also possible via the 
chucking attachment: 
first tool drive means within the region of said first fastening means, 
said tool chucking attachment comprising second tool drive means extending 
to the region of said second fastening means, and 
coupling means for coupling said first and second tool drive means. 
Even when the following features are implemented, the advantages of greater 
precision can be realized, and also the provision of a larger number of 
tools, which can be used without change-over time; 
said chucking attachment extends radially beyond said peripheral surface of 
said turret means and comprises a radially inner and an outer end, 
first and second surfaces extending from one end to the other in opposite 
relationship so as to face away from one another, 
said fastening surface of the chucking attachment being arranged within the 
region of said radially inner end on the first surface, while said second 
fastening means together with said fast-locking means are on the radially 
outer end and are arranged on said second surface to hold one of said 
tools substantially parallely to said axis of rotation. 
The above mentioned features thus have in common the fact that an 
additional chucking attachment can be fastened to the fastening means on 
the turret head, which additional chucking attachment in turn carries 
fastening means for a tool holder or a tool head and by means of which the 
tool can be positioned more exactly at a preselected point. This is 
particularly advantageous in the conversion of existing machine tools, for 
example including grinding or planing machines with reciprocating 
movement, but generally turning machines, which can now be converted to 
greater precision and cost-efficiency without high capital costs. Through 
the last mentioned features, furthermore, the number of tools to be 
carried by a turret is increased in that its existing fastening means are 
multiplied by the chucking attachment, and, owing to the embodiment with 
fast-acting locks, rapid tool change is possible here too. Thus, a 
chucking attachment can be fully equipped during operation of the machine 
and then need only be connected to the fastening means of the turret. It 
is not at all necessary for the chucking attachment to have only the two 
fast-acting locks; for example, it may itself be in the form of a turret, 
which then fits into a larger turret. Machining operations which are 
carried out in succession with a plurality of tools can thus be carried 
out more rapidly since a small (additional) turret is of course more 
convenient to handle. With an appropriate embodiment of the control, it is 
even possible to process two workpieces simultaneously, or at least 
rapidly in succession. 
Machining in two opposite directions is also possible. 
However, the precision and speed is also increased as a result of the 
following features, with simultaneous reduction in the change-over time as 
a result of dispensing with tedious adjustment and dimensioning: 
numerical control means for automatically controlling a relative movement 
of one of said tools and one of said workpieces, 
code means on said tool head for indicating at least one particular tool 
dimension, and 
code reading means for determining the exact position of the tool when 
considering said tool dimension, said code reading means being connected 
to said numerical control means. 
By means of three features, the tool dimensions, which finally specify the 
position of the tool relative to the workpiece, can be automatically 
communicated to the control without manual input being necessary for this 
purpose. 
A chucking attachment according to the invention is characterized by the 
following features: 
an elongated body of at least approximately prismatic shape, the body 
having two ends in a sufficient distance from each other to extend beyond 
said peripheral surface of said tool turret when mounted on it, said body 
comprising a support surface portion to be applied against said end 
surface, and 
a further surface portion facing away from said support surface portion, 
first and second tool bearing surface portions within the region of one of 
said ends of said elongated body, said tool bearing surface portions 
facing away from each other and extending parallely to or flushing with 
said support surface portion, 
a peg-like extension projecting at right angles from said support surface 
portion within the region of the other one of said ends, and having at 
least one fastening surface to be inserted into one of said tool receiving 
holes; 
first and second tool holding means on said first and second tool bearing 
surface portions, respectively, to connect a headed tool onto each of said 
tool bearing surface portions, said tool holding means each including 
fast-locking means. 
A tool head according to the invention is characterized by the following 
features: 
at least one tool receiving orifice and a clamping member on it, said head 
comprising 
a projecting insertion means for insertion into said tool receiving 
orifice, said projecting insertion means including an annular neck groove 
for engagement with said clamping member. 
By inserting an additional part in between, namely the chucking attachment, 
in addition to the tool head, those skilled in the art presume that noise 
would be produced through vibrations in the course of machining and in 
this connection there were also some reservations about the practical use 
of the invention. It is surprising that the invention has, on the 
contrary, even led to a reduction in operating noise. In retrospect, the 
only explanation for this is that the individual connections via the 
fastening means are rigid enough to combine the individual parts into an 
overall integral part; however, since each of the individual parts has its 
own different frequency, the tendency for vibration noise decreases.

A turning machine 1 (FIG. 1) has a conventional chuck 2, in which a 
workpiece can be clamped, and tools 3, 4 which serve for machining such a 
workpiece. The workpiece is rotatable via the chuck 2 with the aid of a 
drive shaft 5, for example, to permit execution of a plunge cut by means 
of the tool 4. The drive shaft 5, which is indicated merely by a dash-dot 
line, carries at its other end a drive wheel 6 which is driven by a wheel 
8 on a hollow shaft 7. The wheel 8 is connected to a drive motor 9 via a 
switchable coupling 10, whose switch lever 11 can be brought into three 
different positions, the hollow shaft 7 being coupled in the uppermost 
position shown, a shaft 7' passing through the shaft 7 also being 
connected in a middle position and only the said shaft 7' being connected 
in the lowermost switch.