WO2008097085A1

WO2008097085A1 - Coupling for connecting two elements in a manner restrained from rotation in one direction of rotation, and drilling machine equipped therewith

Info

Publication number: WO2008097085A1
Application number: PCT/NL2008/050064
Authority: WO
Inventors: Gerrit Cornelis Koese
Original assignee: Gerrit Cornelis Koese
Priority date: 2007-02-06
Filing date: 2008-02-05
Publication date: 2008-08-14
Also published as: EP2167261A1; NL1033343C2

Abstract

The invention relates to a coupling (l) for connecting two elements, for instance a drill (2) and a drive shaft (3), in a manner retrained from rotation in one direction of rotation. The coupling (1) comprises a conical coupling part (5) which is fixedly connected to one element, and a conical bore (7) which is provided in the other element. The coupling part (5) and the bore (7) are provided with a cooperating screw thread-like profile (10) with a smooth, undulating configuration, viewed in a central longitudinal plane of the coupling part (5) and the bore (7). The invention further relates to a drilling machine (15) equipped with at least one coupling according to the invention.

Description

P80231PC00

Title: Coupling for connecting two elements in a manner restrained from rotation in one direction of rotation, and drilling machine equipped therewith.

The invention relates to a coupling for connecting two elements in a manner restrained from rotation in one direction of rotation.

The coupling according to the invention is characterized by a conical coupling part which is fixedly connected to one element, and a conical bore which is provided in the other element, wherein the coupling part and the bore are provided with a cooperating screw-thread like profile with a smooth, undulating configuration, viewed in a central plane of the coupling part and the bore.

Such a coupling according to the invention has a number of surprising advantages. For instance, owing to the conical and undulating configuration of the screw thread like profile, a relatively high torque can be transmitted in a first direction of rotation, while the coupling can be detached with a relatively low torque (in the opposite direction of rotation). Further, owing to the above-mentioned design, only approximately one third of a revolution is required for coupling or uncoupling, respectively, the respective elements, so that these operations can be carried out very rapidly. This is of course particularly advantageous in uses wherein large amounts of elements are to be regularly coupled and uncoupled, such as, for instance, the drills of a multi-spindle drilling machine. By providing the coupling part with a conical configuration (instead of a cylindrical reduction, as is typically done with known couplings of this type) the coupling part maintains a large operative surface, which is favourable for the clamping force and the maximum torque to be transmitted, while still, a very slim coupling can be obtained, wherein the diameter of the element with the bore needs hardly be greater than that of the element with the coupling part. As a result, a coupling according to the invention is eminently suitable for coupling of elements that both have substantially the same diameter, or for coupling of elements on locations with little space. An example of such a use is, for instance, again, a multi-spindle drilling machine. Naturally, a coupling according to the invention is also suitable for other uses, wherein the diameters or dimensions of the elements to be coupled can vary and/or can differ from each other. For instance, in the conical bore, drills with different diameters can be placed. When two elements to be coupled are of substantially equal diameter, the conical coupling part will be included substantially entirely in the conical bore upon connection of the elements. However, if the element provided with the conical coupling part has a greater diameter than the element provided with the conical bore, upon connection of the elements, the coupling part will be included only partly in the conical bore. Logically, a part of the first element and the conical coupling portion provided thereon will be included completely in the conical bore upon connection of the elements, when the diameter of the first element is smaller than the diameter of the second element.

Further, according to a further elaboration of the invention, it can be favourable that the pitch of the screw thread-like profile varies, for instance decreases in the direction of the nose angle of the coupling.

Owing to the smooth, undulating configuration of the screw thread- like profile, at least the absence of sharp, angular transitions, the chance of notches being formed is reduced so that a coupling according to the invention is less susceptible to fatigue and its total life span can increase.

A coupling according to the invention can further be manufactured at relatively limited costs, by means of, for instance, grinding, pressing or rolling. This is particularly favourable in a use wherein drills are used, as they wear and must be regularly replaced.

According as, furthermore, the undulating pattern is of finer design, less material will have to be removed and manufacture will therefore take place more rapidly and at more reduced costs. In the further subclaims, further advantageous embodiments of a coupling according to the invention and a drilling machine equipped therewith are described. In clarification of the invention, an exemplary embodiment of a coupling according to the invention, and a use therefor will be explained in further detail on the basis of the drawing. In the drawing:

Fig. 1 shows a coupling according to the invention; Fig. 2 shows a coupling according to a further embodiment of the invention; and

Fig. 3 shows a multi-spindle drilling machine, provided with several couplings according to Fig. 1, for coupling drills to respective drive shafts.

Fig. 1 shows a possible embodiment of a coupling 1 according to the invention for connecting two elements, in the example shown a drill 2 and a drive shaft 3, in a manner restrained from rotation in one direction of rotation. The coupling 1 comprises a conical coupling part 5 and a conical bore 7, which, in the example shown, are provided on a shaft 4 of the drill 2, or in an end piece 6 at the end of the drive shaft 3, respectively. However, in alternative embodiments, the above-mentioned configuration can be reversed, i.e., the coupling part 5 can be provided on the drive shaft 3 and the bore 7 can be provided in the shaft 4 of the drill 2 or an end piece. The bore 7 can be further provided in the drive shaft 3 itself instead of in a separate end piece 6 as shown in Fig. 2. However, use of an end piece 6 offers the advantage that the bore 7 can easily be replaced without this requiring the entire drive shaft 3 to be replaced.

The coupling part 5 and the bore 7 are provided with an external or internal, respectively, screw thread-like profile 10 according to the invention. This profile 10 has a smooth, undulating configuration, without angular, abrupt and/or sharp transitions. Such a screw thread-like profile 10 can be manufactured in a simple manner, for instance by means of grinding. As the profile 10 is smooth and undulating, firstly, the grinding stone will wear little. Secondly, wear of the grinding stone will have relatively little influence on the operation of the screw thread-like profile 10. When the grinding stone levels off, the undulating form of the screw thread-like profile 10 will also become more level. This has no particular influence on the operation of the screw thread-like profile 10 as, upon attachment in the conical bore 7, the screw thread-like profile 10 only requires two contact lines for a solid coupling. It is not required that the conical coupling part 5 contacts the conical bore 7 over the entire surface. Therefore, such a manufacture of the screw thread-like profile 10 leads to little spoilage, which is favourable for the manufacturing costs. Furthermore, the profile 10 shown has a slight undercut so that, in coupled condition, the coupling 1 can absorb axial tensile forces (in the direction of the arrow A). Only a very slight undercut is required for absorbing the axial forces. Upon manufacture therefore, little material is to be removed, so that the manufacturing process, for instance the grinding, has a short time cycle. Preferably, the screw thread-like profile 10 of the conical coupling part 5 has a pitch that is substantially 0.25 times - 0.5 times, more particularly substantially 0.33 times the size of the diameter of the drill 2. It is also favourable when the nose angle α of the conical coupling part 5 is 20° - 60°, more particularly 25° - 40°. The screw thread-like profile 10 of the coupling part 5 and the bore 7 effects the tightening of the coupling 1 and the rigidity of the coupling 1. As a result, it is not required for the coupling 1 to comprise a stop, for instance on a side of the conical bore 7 remote from the conical coupling part 5 or on a side of the conical coupling part 5 remote from the conical bore 7.

As can be seen in Fig.2, the coupling 1 has a slender form, with a total diameter D which is substantially equal to the diameter d of the drill 2 to be connected or, as can be seen in Fig. 1, with a total diameter D which is only slightly greater than the diameter d of the drill 2 to be connected. The coupling 1 according to the invention is further particularly suitable for use with drills with small diameter, for instance from 0.5 tolO mm. As a result, a coupling 1 according to the invention is highly suitable for use in a multi- spindle drilling machine 15 as shown in Fig. 3. Such a drilling machine 15 can be used, for instance, for providing unique patterns of holes in workpieces. Such unique patterns of holes can serve as identification code with which the respective workpieces can be traced. Especially with such a use, the space between the holes is often limited (for limiting the total dimensions of the drill pattern) so that also the space for clamping the drills 2 is limited. In that case, a coupling 1 according to the invention brings relief. Furthermore, with this, the drills 2 can be replaced in a very simple manner, with relatively little force and, furthermore, in a rapid manner (owing to the one-third revolution). For a more detailed description of such a drilling machine 15, the operation and possibilities of use thereof, reference is made to EP 0 251 388 and to the Dutch patent application entitled "Multi-spindle drilling machine" of the same applicant and with the same filing date as the present application. The content of both above-mentioned documents is understood to be incorporated herein by reference.

Naturally, a coupling 1 according to the invention can also be advantageously used in other applications, for instance in a drill press. As a rule, known couplings for such drill presses utilize a cylindrical screw thread connection. However, this can become ever tighter during drilling, so that after use, unscrewing of the coupling can be very difficult. With a coupling 1 according to the invention, the tool can simply be tightened and loosened through an approximately one-third revolution without this requiring a large loosening moment and without special tools.

The invention is not limited in any manner to the exemplary embodiment represented in the description and the drawing. All combinations of (parts of) the described and/or shown embodiment are understood to fall within the inventive concept. Furthermore, many variations thereon are possible within the framework of the invention outlined by the claims.

The undulating configuration of the screw thread-like profile for instance can be a substantially randomly undulating (yet smooth) configuration. Alternatively, the undulating form can be built up completely or partly from predetermined geometric figures, such as arcs of circles, sinuses, clothoids and/or the like. The screw thread can be of single-thread or multi- thread design, for instance be double-threaded. The pitch can be constant or can vary, for instance decrease towards the nose angle of the coupling. The nose angle can be varied in order to influence the magnitude of the required unscrewing torque. This unscrewing torque will therefore be greater according as the nose angle is smaller. The pitch of the screw thread-like profile can be chosen to be relatively fine or, conversely, relatively coarse, for influencing the clamping force of the coupling. This clamping force will therefore increase according as the pitch is chosen to be smaller. The undulating profile in combination with the nose angle can be chosen such that the coupling comprises or does not comprise undercuts. In the first case, the coupling will be able to absorb axial (tensile) forces, in the second case it will not. These and many variations are understood to fall within the framework of the invention as set forth in the following claims.

Claims

1. Coupling for connecting two elements in a manner restrained from rotation in one direction of rotation, comprising a conical coupling part which is fixedly connected to one element, and a conical bore which is provided in the other element, wherein the coupling part and the bore are provided with cooperating screw thread-like profiles with a smooth, undulating configuration, viewed in a central longitudinal plane of the coupling part and the bore.

2. A coupling according to claim 1, wherein the undulating configuration of the screw thread-like profile is at least partly sinusoidal.

3. A coupling according to claim 1 or 2, wherein the undulating configuration of the screw thread-like profile is at least partly formed from arcs of circles.

4. A coupling according to any one of the preceding claims, wherein the undulating configuration of the screw thread-like profile is at least partly formed from quadrants.

5. A coupling according to any one of the preceding claims, wherein the pitch of the screw thread-like profile varies, for instance decreases in the direction of the nose angle of the coupling.

6. A coupling according to any one of the preceding claims, wherein an unscrewing torque for detaching the coupling is adjustable by varying the nose angle of the conical coupling part and/or the pitch of the screw thread.

7. A coupling according to any one of the preceding claims, wherein the screw thread-like profile comprises undercuts, for absorbing axial forces in coupled condition.

8. A drilling machine comprising at least one drill, one drive shaft and one coupling according to any one of the preceding claims, wherein the at least one drill is detachably coupled to the respective drive shaft by means of the respective at least one coupling.