US3842947A

US3842947A - Arresting device

Info

Publication number: US3842947A
Application number: US00297922A
Authority: US
Inventors: D Hofmann
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-08-01
Filing date: 1972-10-16
Publication date: 1974-10-22
Anticipated expiration: 1991-10-22

Abstract

A device for detachably arresting two elements moveable relative to each other, in which each of said elements at the arresting region has at least one passage preferably extending in a direction perpendicularly to the relative movement of said elements, each passageway having two angularly located opposite wall means adapted to engage a ball selectively insertable into the said passage means of said two elements for interlocking the same. The passage means and balls can be arranged to control, or to accomplish indexing of the two elements into predetermined positions and to lock the elements in the respective indexed positions thereof.

Description

0 United States Patent 1191 1111 3,842,947 Hofmann Oct. 22, 1974 ARRESTING DEVICE 2,772,586 12/1956 Jones 74/813 3,002,589 i l 1 1mm new Hofmann, Euunger Stress, 3,169,667 31132; $2226, 133123 7531 Kleselbron" bel Pforlhelm, 3,554,337 1/1971 Denkowski 192/71 Germany 3,589,213 6/1971 Gourley 74/826 22 F1 d: Oct. 16 1972 1 1e Primary Examiner-George E. A. Halvosa PP 297,922 Assistant Examiner-Edward R. Kazenske Related US Application Data Attorney, Agent, or Firm-Walter Becker [63] Continuation-impart of Ser. No. 59,451, July 30,

1970, abandoned. [57] ABSTRACT A device for detachably arresting two elements move- [30] Foreign Application Priority Data able relative to each other, in which each of said ele- Aug. l, 1969 Germany 1939207 ments at the arresting region has at least one passage preferably extending in a direction perpendicularly to [52] U.S. Cl 188/69, 188/31, 192/71, the relative movement of Said elements each P 74 3 3 L, 74 3 7 74 23 way having two angularly located opposite wall means [51 Int. Cl. B62c 7/02 adapted to engage a ball selectively insertable into the 53 Field f Search n 188/31, 6(), 19 7 said passage means of said two elements for interlock- 7 13 R, 7 3 L 323 2 29 5 A ing the same. The passage means and balls can be arranged to control, or to accomplish indexing of the 5 References Cited two elements into predetermined positions and to lock UNITED STATES PATENTS the elements in the respective indexed positions th f. 2,493,232 l/l950 Dodge 192/7] ereo 0 2,733,620 2/ 1956 Nanni 74/813 9 Claims, 7 Drawing Figures PAIENIEDmzzmu 3, 842,947

sum 1 or 3 lnrenzar:

PAIENTEU 22 I974 3, 842 947 sum 3 or a //2 V 0/2 far ARRESTING DEVICE RELATED APPLICATION This application is a continuation-in-part of my pending application, Ser. No. 59,451, filed July 30, 1970, now abandoned and entitled Arresting Device.

The present invention concerns a device for detachably arresting two structural elements adapted to move relative to each other, and especially concerns structural elements of the precision machine art. Further, the device can be arranged to index, or to control the indexing of, the elements into respective relative positions and arrest the elements in the respective indexed positions.

Especially in connection with the precision machine art, it is frequently necessary that two structural elements which are displaceable or rotatable, one with regard to the other, have to be arrested at least one certain predetermined and, if desired, selectable point, or area and have not only firmly to be arrested with regard to each other but also with a minimum possible tolerance. Generally, in this connection, one structural element is stationary whereas the other structural element is moveable relative to the said stationary structural element.

This requirement has to be met, for instance, in connection with indexing devices or indexing tables where a turntable is arranged above a stationary support, said turntable being adapted to be turned through preselectable angles. In each respective position of the turntable, it is necessary to arrest the turntable for purposes of machining operations, while the machining precision will depend on the correctness of the angles and, of course, also on the firm arresting.

With heretofore known designs of the type involved, racks or gear rings were provided on the structural elements which move relative to each other while the racks and gear rings engage each other in the arrested positions of the elements so that relative movement thereof is prevented. The tolerance of the relative displacement in the various positions of the elements is dependent on the precision of the aforesaid teeth and varies between the individual arresting points. Thus, for instance, with a turntable, the tolerance may be within limits when a rotation of 30 is involved, but may be outside limits at other indexing angles.

In addition thereto, it is necessary that the structural elements, when disengaging the arresting means, have to be lifted off in a direction perpendicular to the direc- 'tion of the relative movement of said elements and have to be displaced relative to each other and then have again to be moved toward each other until a firm engagement with the rack or gear ring has again been established. The wear which is unavoidable with these operations of movement naturally increases the tolerance at the arresting points so that structural elements arrested in this manner will, after a relatively short period of use, no longer be usable for the precision machine art.

Moreover, on indexing devices of the type mentioned, machining in a direction perpendicular to the direction of relative movement of the structural elements cannot be carried out because the height of the surface of a workpiece to be machined thereon is dependent on the interengagement of the two racks or gear rings.

In addition thereto, devices of the just mentioned type require considerable adjusting time in view of the moving-in and moving-out of the moveable elements into engagement, and, since the time required for these operations represents idle time, such devices considerably increase the cost of a workpiece machined on a turntable, or structural element, having such an arresting arrangement.

It is, therefore, an object of the present invention to provide a device for detachably arresting two structural elements which move relative to each other, especially structural elements of the precision machine art, which will overcome the above mentioned drawbacks.

It is another object of this invention to provide a device as set forth in the preceding paragraph, in which the structural elements to be moved relative to each other will be firmly and precisely arrested in precise relative positions without the necessity of lifting the same off relative to each other.

A still further object of the invention is the arrangement of an arresting device of the nature referred to which can also accomplish, or control, indexing of the structural elements from one arrested position thereof to the next.

These and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawings, in which:

FIG. 1 illustrates, in a diagrammatic isometric view, a device according to the present invention.

FIGS. 2 and 3 are sectional views respectively illustrating unlocked and locked positions of a locking or arresting device similar to that of FIG. 1.

FIG. 4 is a view of the device of FIGS. 2 and 3 in locked position as seen in the direction of the arrow X on FIG. 3.

FIGS. 5 and 6 illustrate a locking device according to the invention with curved control passages so that the arresting device can also accomplish indexing of the pertaining elements.

FIG. 7 shows a further modification of the device according to the invention, also for both indexing and arresting the pertaining elements.

BRIEF SUMMARY OF THE INVENTION The device according to the present invention is characterized primarily in that the structural elements to be moved relative to each other are at each arresting point provided with at least one passage, or groove, which preferably is located perpendicularly with regard to the direction of relative movement of the elements and has walls which diverge toward the other passage, or groove, said device furthermore being characterized in that a ball is provided which is adapted to be inserted into the two oppositely located passages, or grooves, said ball contacting each wall of each of the passages at one point, whereby the ball makes four points of contact in all.

DETAILED DESCRIPTION OF THE INVENTION ment 1 is chamfered at 3 at an angle of approximately 30.

On inclined edge 3, a second structural element slides which is likewise provided with a milled-in passage 4 of which, however, for the sake of clarity, merely the mantle lines are illustrated in FIG. 1.

Passage 4 has a flank angle which is uniform over its entire length but which continuously decreases in depth so that the open edges of the passages define an angle B of approximately 60. The bottoms of the passages are disposed at an angle y relative to each other. The two elements may be so disposed as to define with each other an angle of approximately 90.

Insertable into the passages 2, 4 is a ball 5. When ball 5 is inserted into the passages, the ball is under the load of a force P (arrow 6 in FIG. 1) and is urged in the direction of the bisector of the angle y. As a result of thrusting ball 5 as described, the walls 7 of passage 2, and the walls 8 of passage 4 are engaged by the ball 5 and are contacted at the four points indicated at 9 and 10.

In the described manner, a rigid connection between the two structural elements is established and thereby a reliable arresting of the elements relatively is brought about. Depending on the steepness of the flank angles a, and or, of the

passage walls

7, 8, a self-locking effect is produced so that the arresting will also be resistant against high lateral pressure forces, or with greater flank angles 01,, a, the arresting will be made ineffective at a certain force exerted between the elements in the direction of relative movement thereof because ball 5 will be pressed out of the passages 2, 4.

Referrence may be had to FIGS. 2 to 6 for further views of the described arresting device. FIGS. 2't0 4 show the control means 12 for the ball 5. The control means includes a resilient jaw 13 engaging the outer circumference of ball 5. FIG. 2 shows the guiding means 12 pulled downwardly as indicated by the arrow 14, so that ball 5 is disposed outside the range of passages 2, 4. The device is thus unlocked, and moveable part is freely displaceable along part 1.

In contrast thereto, according to FIG. 3, the control means 12 has been displaced upwardly, as indicated by arrow 14a so that ball 5 is pressed into passages 2, 4 with the result that the moveable part 15 is safely arrested with regard to the stationary part 1. FIG. 4 is a view looking in the direction of the arrow X on FIG. 3 with the control means 12 in the position of FIG. 3.

Resilient jaw 13 has a hook portion 13a which will move ball 5 downwardly when control means 12 moves downwardly. Jaw 13 also has a portion 13b which engages ball 5 substantially at the point where the aforementioned bisector of the angle between passages 2 and 4 intersects the surface of the ball. Portion 13b is yieldable and will, therefore, press ball 5 into engagement with the passages, or grooves, while permitting the ball to adjust into engagement with each wall of each groove.

From the above, it will be evident that in contrast to heretofore known designs, it is no longer necessary to lift the respective two structural elements off from each other in order to make the arresting ineffective but, instead, merely the arresting member, namely, the ball entering the two passages, is displaced whereby the structural elements may retain their fixed distance from each other also during relative displacement. The advantage is thereby obtained that also the location as to the height of the moveable element can always be retained uniform and it will also be possible, for instance,

to machine a workpiece on the moveable element also in this direction without any problems.

Also, wear will be reduced to a minimum in view of the fact that no bearings with two degrees of movement are required, and machine elements have to be employed for lifting the structural elements off with regard to each other. Further, a considerable saving in time is realized inasmuch as the removal of the relatively light balls from the passages naturally takes less time than the lifting off of heavy structural elements from each other. In addition thereto, the relative movement can practically start with the return movement of the balls, and also prior to the end of the movement, the balls can be moved to the arresting area.

The most important feature of the device according to the invention is seen in the fact that, independent of the machining of the passages, the ball will adjust itself in the passages always so that it will at any rate in each passage engage two points whereby the arresting area is definitely fixed and a rigid but nevertheless detachable connection of the two structural elements is obtained through the intervention of the ball.

If the passages are so arranged that respective central planes thereof define an angle which is different from zero or 180, the flank angle as well as the depth of the passages will remain constant over the entire length thereof. With an angle 180, in other words, when the passages at the arresting areas are located one above the other, at least one of the passages must narrow, for instance, by decreasing at least one flank angle of a passage wall, or by reducing the depth of the passage. This step may, of course, also be taken when the central planes of the passages define an angle which is different from 180.

In order, during the manufacture of the device according to the invention, to save material, it is suggested so to design the passages that the passage walls will extend far enough to effect tangential contact with the ball. Such tangential contact is important in order to be able to convey definite pressure forces to the passage walls. Material which extends beyond the points of contact with the ball is, however, aids the rigidity of the passage walls.

While only one ball has been shown, several may be employed distributed along the structural elements, or parts. Thus, several passages 2 may be provided in part 1 and a ball 5 associated with each passage. In part 15, the passages 4 are then so arranged that in each indexed position of part 15, at least one passage 4 registers with a passage 2 of part 1 so the respective ball 5 can be moved into locking position.

According to the present invention, the central planes of the oppositely located passages may define with each other substantially any desired angle, such as for example, or may be designed so as to follow a curve, preferably a sine curve ending toward the point of reversal. With this shape of the curve, it will be appreciated that movement of the balls will cause with the balls engaging the passage walls, movement of the balls will cause a relative displacement of the structural elements so that, in this way, indexing of the elements under controlled conditions can be obtained. It is understood that there is preferably a further force exerted on the elements so that the device of the present invention will control the indexing and effect the arresting of the elements.

FIGS. 5 and 6 show an index controlling and locking arrangement according to the present invention with curved passages 17 in the fixed part 1 while moveable element has straight passages 18 therein. Inserted between the fixed or stationary part 1 and the moveable part 15 is a control plate 16 which serves for actuating and guiding balls 5. When control plate 16 moves laterally to the direction of movement of part 15, balls 5 will be forced to carry out a kind of single-shaped movement along passages 17 whereby also the moveable part 15, due to with straight passages 18 therein is displaced in the direction of the arrow 19. The part 15 is preferably biased in the direction in which it is to move by a motor (not shown).

During a return movement of the control plate 16, the moveable part 15 is again permitted to index in the same direction as before by one step. At the completion of each indexing step, the balls are disposed in an extreme end position in passages 17, and the moveable part 15 is arrested in a definite position by engagement of balls 5 with the flanks of the respective passages 17 and 18. In this way there has been provided a device which is a most simple manner not only controls the indexing of two structural members relative to each other but also arrests the same relative to each other at the end of each indexing step.

FIG. 7 illustrates a possible modification of a combined indexing-arresting device according to the invention in which the power for indexing may be supplied by the balls. The stationary part 21 is provided with four parallel prismatic passages 22 disposed at an angle in the indexing direction. In the same region, moveable part has five prismatic passages 27 parallel to each other and to passages 22 of part 21. The balls can be moved in the respective passages 22 into and out of the range of passages 27 in part 20.

Balls

23, 2 1, 25 and 26 are disposed in the respective passages 22 and are individually moveable along the respective passages. Ball 23 engages a respective passage 27 of the moveable part 20 and thus locks the moveable part 20 in the illustrated position.

For purposes of indexing the moveable part 211 in the direction of the arrow 28, ball 23 is pulled out of the respective said passage 27 while simultaneously ball 24 is pressed into the adjacent passage 27. Since the moveable part 20 in the illustrated example over the same length of the said four passages 22 of stationary part 21, has five passages 27, the aforementioned ball movement causes part 20 to be advanced by one-fifth of this length. At the same time the moveable part 20 is again arrested or locked in this position. The arresting of the moveable part is precise because when a ball is disposed in a passage in each part, the ball will engage a point on each flank of each passage.

If desired, also a plurality of this arrangement may be employed distributed along two oppositely located structural elements so that a multiple locking will be effected by a simultaneous engagement of a plurality of balls. Furthermore, the invention is not limited to a subdivision of four-fifths of the said length, but any desired pitch or division, e.g., one with a vernier pitch, may be employed. For purposes of a better illustration, the

parts

20 and 21 have been shown in FIG. 7 tilted open at an angle of 6. In actuality,

parts

20 and 21 are so disposed that the passages thereof are parallel to each other.

The pressing of a ball into the passage walls can be effected in various ways. The simplest device to this end would be a manually operable eccentric lever, especially when only one or two pairs of passages are provided for the arresting operation. This may, for instance, be the case with a vise which is to be turned on a supporting plate and is to be arrested by a device ac cording to the invention.

If, however, a plurality of pairs of such passages is provided, it is advisable to press the balls in a yieldable manner against the passage walls either by spring force, centrifugal force, force of gravity or pneumatic or bydraulic means. In this way a ball will be able to adapt itself to the respective passage walls in an optimum manner so that the desired rigid connection between the two structural elements through the intervention of the ball will be realized. The machining precision within a certain tolerance is in this way compensated for.

For returning the ball from its arresting position, the ball may, according to the invention, be engaged by a hook-shaped returning device or may be mounted on an actuating rod. It is also possible to press the ball out of its arresting position by any standard hydraulic or pneumatic means.

It will be appreciated that whenever the relative moveable parts or elements are in an arrested position, the ball, or balls, which serve precisely to locate the said elements relatively engage a point on each of the opposed walls of each passage, or groove, pertaining thereto. Where the function to be carried out by a ball and a pair of passages is solely for the purpose of arresting the elements in a predetermined relative position, the passages, or grooves, can taper inwardly so as to converge in the direction in which the ball is moved into arresting, or locking, position.

Furthermore, the two walls of each such passage, or groove, are so disposed as to converge in a direction away from the center of the ball.

The ball is thus precisely located with reference to the passage, or groove, in one part, usually a stationary part, and the other part, usually the moveable part, is precisely located relative to the ball. In this manner, precise location of the parts relative to each other is thereby obtained.

When the ball is utilized not only for arresting and locating purposes, but also for controlling the indexing movement of the parts relatively, the ball is substantially confined within the passages in the parts and the passages do not, in this case, taper :inwardly in the manner described above, although each such passage has a pair of opposed walls which coverge in a direction away from the center of the ball so that the ball will always have four points engagement with the two parts.

In the case where the ball accomplishes the indexing movement as by force a pair of passages in the respective members into registration, the passage may be substantially uniform in cross section and, as before, each passage is made up of opposed walls which converge in a direction away from the center of the ball so that the ball engaged in each of a pair of opposed passages will have four point engagement with the two parts containing the passages, or grooves.

As has been mentioned, a single pair of grooves and a single ball will provide for one located position of the parts relatively, but as many grooves as desired could be provided in each part and the grooves of one part may register singly or in multiple with grooves in the other part for arresting and locating or for controlling indexing movements between the parts or for causing the said indexing movement.

It is, of course, to be understood that the present invention is, by no means, limited to the particular showing in the drawing but also comprises any modifications within the scope of the appended claims.

What is claimed is:

1. In combination on an arresting device; first and second members which are relatively moveable in a predetermined direction, said members having portions in adjacent parallel relation and parallel to the direction of relative movement of said members, each said portion having at least one groove means therein opening toward the other of said portions and extending at an angle to said direction, a groove means in one of said portions registering with a groove means in the other of said portions when said members are in a predetermined relative position, each groove means having side walls which converge in a direction away from the other said groove means, said groove means when in registration defining a passage having four angularly related walls all extending at an angle to said direction, ball means of predetermined diameter receivable in said passage in simultaneous engagement with all of said four angularly related walls to arrest said members in said positions, said ball means being insertable into and withdrawable from said passage at one end of the passage, and a ball control element on one of said members located for movement thereof in the longitudinal direction of the groove means in the said portion of the respective member, said ball control element including means engaging said ball means and being movable for inserting the ball means into said passage and for withdrawing the ball means from said passage, said groove means being inclined relative to each other to cause said passage to diminish in cross section in a direction away from said one end thereof, said ball means engaging on the side thereof which faces directly away from the said one end of the passage.

2. A device in combination according to claim 1 in which said side walls of said groove means are substantially perpendicular to said predetermined direction of relative movement of said members.

3. A device in combination according to claim 1 in which said ball means is insertable into and removable from said passage at one end of the passage, and at least two of said side walls coverge in a direction away from said one end of the passage.

4-. A device in combination according to claim 1 in which each said side wall extends into full tangential engagement with said ball.

5. A device in combination according to claim 1 in which said means resiliently engages said ball means.

6. A device in combination according to claim 1 in which the groove means in one of said portions is disposed at an angle to the groove means in the other of said portions said ball means upon moving longitudinally in said passage causing relative movement of said members in said predetermined direction.

7. A device in combination according to claim 6 in which the groove means in one of said portions is in substantially zig-zag form said ball means upon moving from one reversing point of the zig-zag groove means controlling to the next relative movement of said members while the ball means when disposed at a said reversing point arrest the members in a respective predetermined relative position.

8. A device in combination according to claim 7 in which each leg of said zig-zag groove means is substantially sine shaped.

9. A device in combination according to claim 1 in which the groove means in each of said portions is in the form of a plurality of adjacent parallel grooves each of uniform cross section from end to end, the grooves in one portion being parallel to those in the other portion, the number of said grooves in a predetermined length of one portion differing from the number of said grooves in the other portion in the same said length, the grooves in said portions registering in successive respective pairs during relative movement of said members in said predetermined direction, a said ball means disposed in a registering pair of grooves arresting said members while removal of a ball means from a registering pair of grooves and insertion of a ball means into another pair of the said grooves which are near a condition of registration will cause relative movement of said members to bring said other pair of grooves into registration.

Claims

4. A device in combination according to claim 1 in which each said side wall extends into full tangential engagement with said ball.