Tool support for tool machines

A tool support for a hand tool machine includes a housing surrounding a drive spindle having a recess to receive a tool-receiving sleeve. This recess accommodates a compression spring which biases an end portion of the sleeve. The sleeve is also provided with a tool-facing portion receiving a tool to be used and an intermediate shaped portion which is arranged for a possible slidable movement within an adapter rigidly mounted to the drive spindle. A second sleeve is provided in the tool support which is threadably mounted on the tool-facing portion of the tool-receiving sleeve and is arranged so that its axial position may be adjusted. Said end portion of the sleeve has such a length that the length of contact of this end portion with the recess should be relatively larger than the combined length of contact of the shaped portion of the tool-receiving sleeve with the inner surface of the adapter and a possible path of the second sleeve in the axial direction. Such a structure provides a quick change of a tool to be used without any potential danger to an operator.

BACKGROUND OF THE INVENTION 
The invention relates to tool supports for tool machines particularly for 
hand tool machines. 
It is known in the art that a tool drive operatively connected to a tool is 
switched on and off independently on contact of the tool with a workpiece. 
The locking-in connection between a drive and a tool is steadily 
maintained by a tool drive. When shut-down of the tool takes place the 
drive lags in the rotational movement from the tool and the whole energy 
of the moving masses in this lagging phase is applied to a tool. This may 
result in potential danger to an operator. Furthermore, this lagging 
effect obstructs the change of the tool unless the complete stopping of 
the tool is attained. The change of a tool during continuous tool driving 
is completely excluded since it is dangerous for an operator. It is 
therefore desirable to prevent the potential danger to an operator working 
with hand-operated tool machines. 
SUMMARY OF THE INVENTION 
It is an object of the invention to provide an improved tool support for a 
hand tool machine. 
Another object of the invention is to provide an improved tool support 
which prevents an operator from a potential danger when a tool to be used 
is changed in case the tool machine is not completely shut down. 
Still another object of the invention is to provide relatively quick change 
of a tool to be utilized. 
These and other objects of the invention are attained by a tool support for 
a tool machine having a tool drive and transmission means adapted to 
operate under working pressures acting in a direction of an axis of 
rotation, where the combination comprises a housing, a drive spindle 
having an end connected to the tool drive and a longitudinal axis recess, 
an inner tool-receiving sleeve having a first end portion received in said 
recess, an intermediate shaped portion connected to said first end portion 
for rotation therewith, and a second end portion adapted to receive a 
tool, biasing means located within said recess and adapted to bias said 
first end portion, an outer sleeve mounted on said second end portion and 
adapted for movement in said axial direction so that its position may be 
adjusted relatively to said spindle, and mounting means connected to said 
spindle and having an inner shaped surface corresponding to the surface of 
said shaped portion and adapted to receive said shaped portion for axial 
movement therethrough. The first end portion of the inner sleeve has in 
accordance with the invention, such a length that the length of coupling 
engagement between the first end portion and said spindle should be 
relatively larger than the combined length of contact of the shaped 
portion with the inner shaped surface of the mounting means and a possible 
path of the outer sleeve in said axial direction. 
The tool support may further comprise locking means mounted on said housing 
and adapted to be selectively positioned in a locking position where said 
locking means limit said movement of said outer sleeve or in a releasing 
position on said housing. 
The biasing means may be a compression spring. 
The mounting means may include an adapter rigidly connected to said spindle 
and a nut positioned within said adapter, said nut being provided with 
said inner shaped surface. 
The compression spring may be prestressed to bias said first end portion 
towards a tool to be used. 
The outer sleeve may extend in an axial direction towards said end of said 
drive spindle and adapted for overlapping an open portion of said spindle 
to thereby prevent the latter from pollution. 
The adapter may be threadedly mounted on the spindle. 
The second portion of said inner sleeve may have an outer thread and said 
outer sleeve has an inner thread so that said outer sleeve is threadably 
positioned on said second portion, said outer thread being relatively 
longer than said inner thread to thereby permit the adjustment of the 
length of contact of said shaped shaft portion with said inner shaped 
surface. 
The second end portion is formed with a recess to receive a tool to be 
used. 
The novel features which are considered as characteristic for the invention 
are set forth in particular in the appended claims. The invention itself, 
however, both as to its construction and its method of operation, together 
with additional objects and advantages thereof, will be best understood 
from the following description of specific embodiments when read in 
connection with the accompanying drawing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to the drawings, and particularly to FIG. 1, a housing or front 
cap 1 of a drilling machine is illustrated. The part of the hand-operated 
machine at the right side of the cap 1 is not shown herein. The front cap 
1 surrounds a drive spindle 3 carrying a pinion 4 at one end thereof and 
supported within a ball bearing 2. The ball bearing is mounted in a bore 5 
provided in the front cap 1 and is axially secured in the cap from a 
slidable movement in a section 6 of the bore 5 by means of the 
corresponding step made in the spindle 3 at one side of the bearing, and 
by means of keys 7 and 8 arranged at the other side of the bearing. The 
drive spindle 3 is formed with an internal axial bore 9 which is vented by 
a radial opening 10 formed at the end thereof. A helical spring 11 is 
inserted into the bore 9. The drive spindle 3 has a threaded end portion 
12 which is normally adapted to receive a tool chuck. In the embodiment 
presented herein, an adapter 13 is threadedly mounted on the end portion 
12 of the spindle 3. A drill 22 or any other suitable tool is rigidly 
mounted in a tool shaft 21 which in turn is inserted into a recess 20 
formed in a tool-receiving sleeve or trunnion 16. The tool-receiving 
sleeve 16 is formed with a specially shaped intermediate portion 17 which 
is engaged in a prismatic half of a nut portion 14 in of the adapter 13. 
One end portion of the tool-receiving sleeve 16 is formed as a head 48 
having an outer thread 18. A radially extending bore 19 also passes 
through the tool shaft 21 and head 48. A cylindrical pin 23 is inserted 
into the bore 19 to interconnect the sleeve 16 with the tool shaft 21 and 
to prevent their rotation one relative to the other. An outer sleeve 24 is 
threadably mounted on the thread 18 of the sleeve 16 by means of an inner 
thread 25 provided in the sleeve 24. 
The thread 25 extends somewhat longer in the lengthwise direction than the 
length of head 48 of the tool-receiving sleeve 16 as is clearly seen in 
FIG. 1. The outer sleeve 24 extends in the axial direction so as to 
overlap adapter 13 and further extends towards the spindle 3 in order to 
protect the adapter 13 and the internal part of the spindle from 
contamination. The sleeve 24 is provided with a flange 26 which is formed 
at one of the ends of the sleeve and is extended outwardly radially from 
the outer surface of the sleeve. The length of the portion 15 is selected 
so that the length of coupling engagement between the portion 15 and the 
spindle 3 is larger than the combined length of contact of the shaped 
portion 17 with the nut portion 14 and a possible path of the outer sleeve 
24. A pin 27 is rigidly mounted in the cap 1 which has a ball-like front 
surface axially outwardly projected from the end face of the cap. The end 
face of the flange 26 is arranged at a predetermined distance from the 
ball-like surface of the pin 27. A longitudinal pin 28 is slidably mounted 
in the cap 1. The pin 28 is also formed with a ball-like end portion 
axially outwardly projected from the end face of the cap 1. The end face 
of the flange 26 bears against the end portion of the longitudinal pin 28 
which serves in the arrangement as a transmitter. The pin 28 is guided in 
an opening 29 formed in the cap 1 and extended parallel to the 
longitudinal axis of the spindle 3. The pin 28 extends within the interior 
of the cap 1 and carries at its second end a movable element 30 of a 
controller 31 which is also shown in FIG. 3. This movable element 30 is 
adapted to move in the axial direction via the longitudinal pin 28 which 
is connected to the element 30 by means of a connecting plate 32. As may 
be clearly seen in FIG. 1, a bearing opening 34 is formed in the cap 1 or 
in an element rigidly connected to the cap 1 to receive a compression 
spring 35 and a pin 33 rigidly secured to the element 30. This compression 
spring 35 constantly tends to slide out from the opening 34 in the 
direction towards the longitudinal pin 28. The controller 31 is so 
constructed that it can control loads exerted on the tool drive during the 
operation in the range from zero to the maximum possible loads. A switch 
36 is provided in the arrangement (FIG. 3) to supply an electric current 
to the tool drive, which switch also serves to supply the current to the 
controller 31. A gripping handle 37 is mounted on a collar 38 of the cap 1 
to which this handle is clamped. A longitudinal bolt 39 with a butterfly 
nut 40 mounted at the end thereof serves as clamping means to connect the 
gripping handle 37 to the cap 1 as clearly seen in FIG. 2. The gripping 
handle 37 is provided with a pin 41 extending parallel to the longitudinal 
axis of the tool drive. A locking plate 42 encircling the upper portion of 
the handle 37 is pivotally supported on the pin 41 and may be pivoted 
about the collar 38 by means of a handle 50. A spring 43 surrounding the 
pin 41 is arranged between the handle 37 and the locking plate 42. This 
spring is prestressed so that the locking plate 42 constantly tends to 
pivot relatively to the collar 38 of the cap 1. A locking ring 44 provided 
in the assembly ensures the position of the plate 42 and the spring 43 on 
the pin 41. The locking plate 42 is provided with a radially inwardly 
projected flange 45. The plate 42 in its turned or pivoted position when 
it is clamped near the collar 38 and the handle 37 can overlap the sleeve 
24. It is to be understood that the flange 45 is placed in the region of 
axial movement of flange 26 of the outer sleeve 24. Therefore, the pin 27 
and the flange 45 in the locking position of the plate 42 limit the 
maximum axial play of the sleeve 24. After the sleeve 24 has been adjusted 
on the tool-receiving sleeve 16 this maximum play is more or less 
utilized. When the axial position of the sleeve 24 is selected relatively 
to the sleeve 16, in other words when the sleeve 16 is so positioned 
relatively to the adapter 13, the maximum axial play is not completely 
taken up before the flange 26 reaches the ball-like surface of the pin 27. 
This means that the front face of the flange 26 of the sleeve 24 is 
adjacent the pin 28 communicated with the controller 31 at relatively low 
speed of rotations of the drive spindle 3. 
As was mentioned above, various machine tools such as a drill or any other 
suitable tools may be preliminarily installed into the tool-receiving 
sleeve 16 of the outer sleeve 24. The sleeve 24 may be moved into such 
axial position on the sleeve 16 that a standard number of revolutions may 
be adjusted by means of the pin 28 when the latter is in contact with the 
front face of the flange 26. In order to change a tool to be used in the 
arrangement of the foregoing type the locking plate 42 is pivoted against 
the action of the spring 43 relatively to the collar 38 of the cap 1. When 
the flange 45 is moved away from the region of axial movement of the 
flange 26, the tool 22 with the sleeve 24 may be taken out. When the above 
mentioned movement of the sleeve 24 to its contacting position with pin 28 
begins the helical spring 11 biases the end portion 15 of the sleeve 16. 
In order to insert a new tool (drill or the like) into the sleeve 16 the 
locking plate 42 must be placed into the corresponding position. The end 
guiding portion 15 is installed into the bore 9 of the drive spindle 3 and 
pressed against the action of the helical spring 11 unless the flange 45 
of the plate 42 engages the flange 26 of the sleeve 24. The released 
locking plate 42 pivots by action of the spring 43 into its locking 
position. At this time a number of revolutions of the tool drive for the 
installed tool is limited by the control arrangement in the range from 
zero to the optimum number. The length of coupling between the nut portion 
14 of the adapter 13 and the shaft portion 17 of the tool receiving sleeve 
16 is so adjusted that when the controller 31 is set up to zero number of 
revolutions both elements being coupled become to move out of the 
engagement. Independently, such adjustment may be obtained when the tool 
is released from the sleeve 16 before the controller 31 reaches its zero 
position. This may be attained by means of selection of the respective 
length of the shaft portion 17 which may be different for each individual 
tool. 
It will be understood that each of the elements described above, or two or 
more together, may also find a useful application in other types of tool 
supports differing from the types described above. 
While the invention has been illustrated and described as embodied in a 
tool support, it is not intended to be limited to the details shown, since 
various modifications and structural changes may be made without departing 
in any way from the spirit of the present invention. 
Without further analysis, the foregoing will so fully reveal the gist of 
the present invention that others can, by applying current knowledge, 
readily adapt it for various applications without omitting features that, 
from the standpoint of prior art, fairly constitute essential 
characteristics of the generic or specific aspects of this invention.