Gripper arrangement for a hoisting apparatus

A gripper arrangement for a lifting or hoisting apparatus serves to transport workpieces having a journal or plug-like end. This gripper arrangement or gripper contains a housing in which two slides are essentially symmetrically arranged and radially displaceably guided with respect to a primary or main axis. At each of the slides there is supported a respective clamping or chucking jaw by means of a related guide device which is connected with the related clamping jaw by means of a radial inner hinge joint and with the related slide by means of a radial outer hinge joint which is arranged further towards the outside in axial direction than the radial inner hinge joint. Within the housing there is rotatably mounted a control body member which is operatively coupled with a drive motor. At the control body member there are formed control cams which, during rotation of the control body member, displace the slides. The axial symmetrically displaceable slides render possible, on the one hand, an accommodation of the gripper to workpieces having different journal or plug diameters and, on the other hand, a rapid, rigid or firm and exactly central clamping or chucking of the journal or plug-like end of each individual workpiece which is handled.

BACKGROUND OF THE INVENTION 
The present invention relates to a new and improved construction of a 
gripper arrangement or gripper for a lifting or hoisting apparatus for 
handling, and especially for transporting workpieces having a plug or 
journal-like end. 
Such workpieces, for instance essentially vertically arranged shafts, which 
are provided at their upper end with a respective journal or plug, also 
king pins or the like, during the course of their machining operation or 
assembly frequently must be removed from one machine or a supply magazine 
and deposited in an exact position at a different location. There is known 
to the art for this purpose hoisting or lifting equipment which is capable 
of accomplishing such type of transport operations with exactly controlled 
movements, for instance along the three axes of a spatial coordinate 
system. 
SUMMARY OF THE INVENTION 
It is a primary object of the present invention to provide a new and 
improved construction of a gripper arrangement or gripper for a hoisting 
or lifting apparatus which enables rapidly and positively seizing, 
transporting and exactly depositing workpieces of the aforementioned type 
at predetermined locations. 
Still a further significant object of the present invention is directed to 
a new and improved construction of gripper arrangement for a lifting or 
hoisting apparatus, which is relatively simple in construction and design, 
quite economical to manufacture, extremely reliable in operation, not 
readily subject to breakdown or malfunction, and requires a minimum of 
maintenance and servicing. 
Yet a further important object of the present invention is directed to a 
novel construction of gripper arrangement or assembly for a hoisting or 
lifting apparatus which enables seizing in a rapid, reliable and positive 
fashion workpieces having a protruding or plug-like portion, and 
maneuvering them to a desired location or site where they can again be 
deposited. 
A further noteworthy object of the present invention is directed to a new 
and improved construction of gripper arrangement for a hoisting apparatus 
which enables reliably, safely, protectively and positively seizing and 
transporting workpieces between various locations and again depositing 
such workpieces at a defined site. 
Now in order to implement these and still further objects of the invention, 
which will become more readily apparent as the description proceeds, the 
gripper arrangement or gripper of the present development is manifested by 
the features that, within a housing connected with the hoisting or lifting 
apparatus there are provided two or more slides or carriages which are 
radially displaceably guided symmetrically with respect to a primary or 
main axis. Each of the slides is provided with a clamping or chucking jaw, 
and a control body member drivingly coupled with a drive motor is 
rotatable about the primary axis. Control cams are formed or provided at 
the control body member, these control cams displacing the slides during 
rotation of the control body member. 
The axially symmetrically displaceable slides or slide members render 
possible, on the one hand, an adaptation of the gripper assembly to 
workpieces having different plug or journal diameters and, on the other 
hand, allows for a rapid, firm or positive and exact central clamping or 
chucking of the plug or journal-like portion of each individual workpiece. 
According to a preferred embodiment constructional embodiment of the 
invention, at least one of the clamping jaws or jaw members is hingedly 
supported at the related slide member or slide, so that it can deviate 
away from or so to speak "side step" the end of the workpiece penetrating 
between the clamping or chucking jaws and it then automatically prevents 
slipping or sliding out of the workpiece of exerting a clamping action 
thereat. This construction of the invention is particularly suitable for 
an elevationally displaceable, i.e. up-and-down movable gripper having a 
vertical primary or main axis. In this case the weight of the workpiece 
itself strives to intensify the clamping action. The slide members or 
slides therefore need only be moved apart to such an extent that the 
clamping jaws now opposingly apply a moderate frictional resistance at the 
plug or journal-like end of the workpiece which penetrates therebetween. 
During lifting of the gripper assembly or gripper arrangement the same 
frictional resistance causes a relative movement between the or each, as 
the case may be, hingedly supported clamping jaw and the related slide 
member, so that the spacing between the clamping or chucking jaws is 
reduced and the end of the workpiece is positively fixedly clamped. 
Advantageously, the or each, as the case may be, hingedly supported 
clamping jaw is supported by means of a guide device at the related slide 
member. The guide device is connected with the clamping jaw by a radial 
inner hinge joint and with the related slide member or slide by a radial 
outer hinge joint, which also in axial direction is arranged further 
towards the outside than the radial inner hinge joint.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Turning attention now to FIG. 1 of the drawings, the hoisting or lifting 
apparatus 10 disclosed therein is assigned the task of transporting or 
conveying workpieces 12, here illustrated as substantially vertically 
arranged shafts by way of example and not limitation, each of which have a 
plug or journal-like upper end 14, from a supply magazine 16 to a machine 
tool 18, here illustrated by way of example as a gear shaper. 
Belonging to the workpiece hoisting or lifting apparatus 10 is a stationary 
vertical column member or beam 20 which is attached to a substantially 
horizontal rail member 22. Displaceable along the rail member 22 is a 
lifting and travel mechanism or unit 24 in which there is vertically 
displaceably guided a vertical tube member or pipe-like element 26. At the 
outer side or surface of the tube member 26 there is formed or provided a 
gear rack 28 with which meshes a rotatably drivable pinion 30 arranged at 
the lifting and travel mechanism 24. At the lower end of the tubular 
member 26 there is arranged a gripper assembly or gripper arrangement 32 
and at the upper end thereof a suitable drive motor 34. 
The gripper assembly or gripper arrangement 32 is symmetrically constructed 
in relation to a vertical primary or main axis A which coincides with that 
of the tubular member 26 and the drive motor 34. Belonging to the gripper 
arrangement 32 is a housing 36 which, as shown in FIG. 2, is bolted to a 
flange 38 secured at the lower end of the tubular member 26. Within the 
housing 36 there are arranged diametrically opposite to one another, in 
relation to the primary or main axis A, two slides or carriages 40 which 
are guided to be radially displaceable. At each slide or slide member 40 
there is supported a clamping or chucking jaw 42 or equivalent structure 
which is structured so as to possess a substantially prismatic 
configuration at its radial inner side or surface, as best seen by 
referring to FIG. 5. 
For the purpose of supporting each clamping or chucking jaw 42 at the 
related slide member or slide 40 there is provided a lower guide device or 
guide link 44 or equivalent structure which is connected by a radial inner 
hinge joint or pivot 46 with the appertaining clamping jaw 42 and by means 
of a radial outer hinge joint or pivot 48 with the related slide member or 
slide 40. The radial outer hinge joint 48 is located somewhat lower, and 
therefore, somewhat closer to the outwardly open lower end of the housing 
36, than the radial inner hinge joint 46. Consequently, each of the guide 
devices or guide links 44 is arranged at an inclination so as to ascend 
radially towards the inside. The ascent of each of the guide devices or 
guide links 44, in the depicted rest position of such guide devices 44 as 
shown in FIGS. 2 and 3, amounts to about 6.degree. with respect to the 
horizontal. 
For the purpose of supporting each of both clamping jaws 42 at the related 
slide member or slide 40 there is provided an upper guide device or guide 
link 44' which is arranged above the guide device or guide link 44 and 
essentially in parallelism therewith. Each guide link 44' is provided with 
appropriate pivots or hinge joints 46' and 48'. The hinge joints or pivots 
46, 48, 46' and 48' are located at the four corners of a parallelogram. 
Both of the guide links or guide devices 44 and 44' thus form in 
conjunction with the related slide members or slides 40 and the related 
clamping jaws 42 a parallelogram link or linkage arrangement which ensures 
that the clamping or chucking jaws or jaw members 42, during each relative 
movement in relation to the related slide member 40, remain parallel to 
themselves. Each of these parallelogram link arrangements is pre-biased 
upwardly by a related spring member 50 or equivalent structure supported 
at the lower guide device 44, and thus is urged against an appropriate 
stop or impact member 52 formed at the corresponding slide member or slide 
40. 
Threadably connected into each slide member 40 from above is a vertically 
extending bolt member 54 upon which there is rotatably mounted a follower 
roll or roller member 56 in such a manner that the free end 58 of the bolt 
member 54 protrudes upwardly past the roll or roller member 56. A 
substantially bell-shaped control body member 60 engages over the bolt 
members 54 and the rolls 56. This bell-shaped control body or control body 
member 60 is mounted in the housing 36 by means of a ball bearing 62 and 
is connected with the drive motor 34 by means of a shaft 64 mounted within 
the tubular member 26. At the inside of the bell-shaped control body 60 
there are formed diametrically opposite one another two identical control 
cams 66 along which travel the follower rolls 56. Two grooves or channels 
68 or the like are machined above the control cam 66 in the control body 
member 60, likewise so as to be located essentially diametrically opposite 
one another, and the course or contour of such two grooves 68 corresponds 
to that of the control cams 66. The upper ends 58 of the threaded bolts 54 
engage with radial play in a respective one of the grooves 68. 
At the underside of the housing 36 there is attached a pre-centering 
bushing 70, the internal space of which widens downwardly in a 
funnel-shaped fashion, as best seen by referring to FIGS. 2 and 3. 
Having now had the benefit of the foregoing description of the hoisting or 
lifting apparatus 10 equipped with a gripper arrangement or gripper 
assembly as contemplated by the invention, its mode of operation will be 
described in detail in conjunction with FIG. 1 and is as follows: 
The lifting and travel mechanism or unit 24 is located above the workpiece 
supply magazine 16 or the like in such a manner that the primary or main 
axis A of the gripper assembly or gripper arrangement 32 is at least 
approximately in alignment with the lengthwise axis of a workpiece 12 
which is to be handled. The tubular member 26 along with the gripper 
arrangement 32 is lowered onto the workpiece 12, so that its journal or 
plug-like upper end 14 is centered by the pre-centering bushing or sleeve 
70, and to the extent still needed, in relation to the clamping or 
chucking jaws 42. Consequently, the journal or plug-end 14 of the shaft 
12, during the further lowering of the gripper arrangement 32, readily 
moves between the clamping jaws 42, even if the intermediate space between 
such clamping jaws 42 is hardly larger than the diameter of the journal or 
plug-like end 14. Now the drive motor 34, which in the illustrated 
exemplary embodiment may be constituted by a transmission-rotating field 
magnet, has its polarity reversed, so that it rotates the control body 
member 60 through a small angle by means of the shaft 64. The housing 36 
is prevented from co-rotating because of the tubular member 26 which is 
displaceably guided within the lifting and travel mechanism 24 but, 
however, non-rotatably. Consequently, the rotation of the control body 
member 60, through the action of the follower rolls 56, causes a radial 
inwardly directed displacement of the slides or slide members 40. 
Participating in such displacement are the clamping or chucking jaws 42, 
since they are prevented by the stop or impact members 52 from upwardly 
deviating or moving. Therefore, the plug or journal-like upper end 14 of 
the workpiece 12 is now fixedly retained with a certain starting force by 
the clamping or chucking jaws 42. 
If the gripper arrangement or gripper assembly 32 is upwardly retracted by 
the lifting and travel mechanism 24, then the workpiece 12 downwardly 
depends, under the action of its inherent weight, between the clamping 
jaws 42. Because of the inclined position of the guide devices 44 and 44' 
the inherent weight of the workpiece 12 generates radial force components 
which are beneficially effective as additional clamping or chucking forces 
between the clamping jaws 42 and the plug or journal-like end 14 of the 
workpiece 12, since the slide members or slides 40 are prevented by the 
rolls 56 supported at the control cams 66 from deviating or shifting 
radially towards the outside. The control cams 66 are constructed or 
configured such that they support in a self-locking fashion the rolls or 
roller members 56. This means that the described radial clamping or 
chucking forces are not capable of causing a rotation of the control body 
member 60. The clamping action therefore also remains reliably intact as a 
result of the foregoing even if the drive motor 34 is without current. 
If the workpiece 12, following its transport to the machine tool 18, should 
be released, then the drive motor 34 has its polarity reversed, so that it 
rotates the control body member 60 in the reverse direction. Consequently, 
the upper ends 58 of the threaded bolts 54 or equivalent structure come 
into contact with the radial inner wall of the related groove or channel 
68 and, during the progressive rotation of the control body member 60, are 
retracted outwardly away from the primary or main axis A. Consequently, 
the clamping jaws or jaw members 42 are released from the end 14 of the 
workpiece 12, so that the gripper arrangement or assembly 32 now can be 
upwardly moved without entraining the workpiece 12. 
While there are shown and described present preferred embodiments of the 
invention, it is to be distinctly understood that the invention is not 
limited thereto, but may be otherwise variously embodied and practiced 
within the scope of the following claims. Accordingly,