Patent Application
20070084320
This application claims priority under 35 U.S.C. § 119 to German Patent Application No. 10 2005 045 752.5, filed on Sep. 23, 2005, the disclosure of which is incorporated by reference herein in its entirety.
The present invention relates generally to a cutting tool including a main tool body and a tool carrier which is movable relative thereto for accommodating a cutting bit, wherein the tool carrier has a screwthreaded bore co-operating with a screwthread on a drive shaft in such a way that the tool carrier can be moved relative to the main tool body by rotation of the drive shaft.
Cutting tools of the type described above have long been known. For example, a boring-out tool is known which has a main tool body, at the end of which there is provided a tool carrier which is adjustable relative to the main tool body, the tool carrier being movable in the radial direction. Here the tool carrier comes into engagement with a drive shaft mounted in the main tool body, by way of a screwthread, so that the tool carrier can be reciprocated in the radial direction by rotation of the drive shaft. As the tool carrier in use carries a suitable cutting bit, the boring radius of the boring-out tool can be adjusted by means of the drive shaft.
For many situations of use, there is a desire to provide for a highly accurate setting of the tool carrier relative to the main tool body. In the case of the known cutting tools, the screwthread of the drive shaft and the corresponding screwthread on the main tool body are frequently in the form of fine screwthreads.
However, fine screwthreads are correspondingly more expensive to produce, in proportion to their respective fineness. In addition, pitches of more than 0.25 mm per revolution are usual. Finer screwthreads can scarcely be produced in practice and are to be implemented at all only with a high level of complication and expenditure.
For many situations of use therefore, the provision of a fine screwthread with a pitch of only 0.25 mm per revolution is still too coarse to easily ensure precise setting of the tool carrier relative to the main tool body.
Therefore, based on that state of the art, an object of the invention is to provide a cutting tool whose tool carrier can be very precisely adjusted relative to the main tool body and which in addition is inexpensive to manufacture.
In accordance with an embodiment of the invention, an object is attained in that the drive shaft has a second screwthread which co-operates with a corresponding screwthread in the main tool body, wherein the two screwthreads of the drive shaft differ in respect of their pitch and/or direction of rotation.
By virtue of such an arrangement, rotation of the drive shaft involves a translatory movement of the drive shaft with respect to the main tool body. The relative movement of the tool carrier with respect to the main tool body is therefore determined by the addition of the relative movements between the tool carrier and the drive shaft, on the one hand, and between the drive shaft and the main tool body, on the other hand. If, for example, the first screwthread of the drive shaft has a pitch of 0.35 mm per revolution and the second screwthread has a pitch of 0.5 mm per revolution, then, with the same direction of rotation of the two screwthreads, the effective relative movement of the tool carrier with respect to the main tool body is 0.15 mm (0.5-0.35) per revolution. The reason for this is that the drive shaft moves relative to the main body by 0.5 mm per revolution; the tool carrier however moves relative to the drive shaft by 0.35 mm per revolution in the opposite direction.
Although the two screwthreads are not of the finest possible configuration, nonetheless a markedly finer adjustable positioning of the tool carrier relative to the main tool body is achieved.
The first screwthread and/or the second screwthread advantageously has a pitch of between 0.15 mm and 0.5 mm per revolution, wherein the relative movement between the main tool body and the tool carrier is established with the same rotational movement by the difference between the two pitches.
In principle, the screwthreads on the drive shaft can be in the form of female or male screwthreads. It has been found however that an embodiment in which the tool carrier has a slider sleeve, wherein the slider sleeve is accommodated in a bore in the main tool body and has a female screwthread which is in engagement with the first screwthread of the drive shaft is simpler to manufacture. In other words, the first screwthread of the drive shaft is advantageously a male screwthread.
A rotation-preventing means may be provided to prevent rotation of the slider sleeve within the bore in the main tool body. For that purpose, the bore could have, for example, a rib-shaped projection which extends axially with respect to the axis of the bore and which enters a corresponding groove in the slider sleeve.
In a further embodiment, the drive shaft has a polygonal socket, preferably a hexagonal socket, for rotating the drive shaft about its axis.
Furthermore in another embodiment, it is provided that the drive shaft has a spindle element and the main tool body has a guide surface, wherein the spindle element has at least two recesses and the guide surface has a projection which upon suitable setting of the spindle element engages into a recess and thereby establishes a position. In that case the spindle element is fixedly connected to the drive shaft so that rotation of the drive shaft causes rotation of the spindle element. An exact position for the drive shaft in relation to the main tool body can be established by the recesses. The drive shaft is moved together with the spindle element until the projection of the guide surface of the main tool body latches into the recess in the spindle element. The recess and the projection are advantageously of such a configuration that upon manual actuation of the drive shaft, latching engagement is noticed, that is to say “felt.”
It will be appreciated that recesses and projection can also exchange their positions so that the recesses are provided in the guide surface while the spindle element has a corresponding projection.
In another embodiment, the projection is formed by a resiliently biased pressure portion.
It has further been found that the spindle element may include a spindle wheel, at the outer edge of which are provided a plurality of grooves forming the recesses.
The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate the presently preferred embodiments of the invention, and together with the general description given above and the detailed description given below, serve to explain features of the invention.
The slider sleeve 9 also has a bush 14 with a female screwthread. In the same manner, a bush 13 within the main tool body 1 is also provided with a female screwthread. The spindle wheel 3 is connected to a drive shaft 15, 16 which here includes two portions of different outside diameters 15, 16. The portion 15 of the drive shaft has a male screwthread which comes into engagement with the female screwthread in the bush 14. Similarly, the portion 16 of the drive shaft has a male screwthread which comes into engagement with the female screwthread of the bush 13.
The drive shaft 15, 16 has two different screwthreads which differ in respect of their pitch and/or their direction of rotation. If, for example, the spindle wheel 3 is rotated in the clockwise direction, the entire drive shaft 15, 16 moves from left to right, that is to say into the tool, by virtue of the engagement with the female screwthread of the bush 13. As at the same time the slider sleeve 9 is connected to the drive shaft by way of the screwthread between the bush 14 and the portion 15 of the drive shaft, the slider sleeve 9 moves relative to the drive shaft 15, 16 towards the left, that is to say into the tool. If, for example, the screwthread on the bush 13 of the main tool body 1 has a pitch of 0.3 mm per revolution and the screwthread on the bush 14 of the slider sleeve 9 has a pitch of 0.25 mm per revolution, then a full revolution of the spindle wheel 3 or the drive shaft 15, 16 causes a relative movement between the slider sleeve 9 and the main body 1 by only 0.05 mm.
As illustrated in
The cutting bit can be highly accurately adjusted by virtue of the configuration of the drive shaft according to the invention.
While the invention has been disclosed with reference to certain preferred embodiments, numerous modifications, alterations, and changes to the described embodiments are possible without departing from the sphere and scope of the invention, as defined in the appended claims and their equivalents thereof. Accordingly, it is intended that the invention not be limited to the described embodiments, but that it have the full scope defined by the language of the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2005 045 752.5 | Sep 2005 | DE | national |
