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Patent Searching and Data


Title:
DEVICE FOR FASTENING TURNING CUTTERS
Document Type and Number:
WIPO Patent Application WO/2003/086705
Kind Code:
A1
Abstract:
The present invention relates to a device (14) for fastening turning cutters (15) to be ground on a rotating grindstone (8). A shaft (1) is in one end rotatably engaged to a sleeve (2) that is slidingly attached to a support bar (9). The other end comprises fastening means for the turning cutters (15). The invention allows for proper grounding of turning cutters (15) with various fastening hole diameters with a minimum of work for the user.

Inventors:
JANSSON TORGNY (SE)
Application Number:
PCT/SE2003/000554
Publication Date:
October 23, 2003
Filing Date:
April 04, 2003
Export Citation:
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Assignee:
TJ UTVECKLING AB (SE)
JANSSON TORGNY (SE)
International Classes:
B24B3/34; B24B41/06; (IPC1-7): B24B3/34; B24B41/06
Foreign References:
SE510362C21999-05-17
DE1928210A11970-12-10
DE29514702U11995-11-16
US5291690A1994-03-08
US5941763A1999-08-24
Attorney, Agent or Firm:
STRÖM & GULLIKSSON (Intellectual Property Consulting AB P.O. Box 4188 Malmö, SE)
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Claims:
CLAIMS
1. A device (14) at a grinding jig for allowing a turning cutter (15) to be ground on a grindstone (8), said device (14) comprising a shaft (1), whose first end has fastening means for fastening the turning cutter (15) and whose second end is engaged to a sleeve (2), characterized in that the shaft (1) is prevented from escaping the sleeve (2) by means of withholding means and in that the turning cutter (15) is fastened by means of a hole or an opening in the turning cutter (15).
2. Device (14) according to claim 1, wherein the withholding means comprise a back screw (4) in the back portion of the shaft (1), engaged in the longitudinal axis of the shaft (1), with a larger head than the inner diameter of the sleeve (2).
3. Device (14) according to any of the claims 1 or 2, wherein the shaft (1) is elongated and have varying diameters.
4. Device (14) according to any of the preceding claims, wherein the shaft (1) is rotatably engaged with the sleeve (2).
5. Device (14) according to any of the preceding claims, wherein the fastening means accommodate turning cutters (15) with various fastening hole diameters.
6. Device (14) according to any of the preceding claims, wherein the fastening means comprise a shoulder (6), upon which a front end surface (10) supports turning cutters (15) with smaller fastening hole diameters than the shoulder (6), the shoulder (6) further having an outer circumferential surface (12) that guides turning cutters (15) with fastening holes larger than the diameter of the shoulder (6), and a surface (11) on the tip of the shaft (1) that support turning cutters (15) with larger fastening hole diameters than the outer diameter of the outer circumferential surface (12) of the shoulder (6); and that the turning cutters (15) are hold in place with a tip screw or other assembly (7).
7. Device (14) according to claim 6, wherein turning cutters (15) with smaller fastening hole diameters than the outer diameter of the shoulder (6) are guided by the tip screw or the other assembly (7).
8. Device (14) according to any of the preceding claims, wherein the shaft (1) is prevented from sliding in too deep in the sleeve (2) by means of a projection (5) provided at an appropriate distance from the tip (3) of the shaft (1).
9. Device (14) according to claim 8, wherein the projection (5) comprise a clamp ring in a circumferential groove.
10. Device (14) according to any of the claims 6 to 9, further comprising means to prevent the shaft (1) from rotating as the tip screw or back screw are tightened.
11. Device (14) according to any of the claims 2 to 10, wherein the head of the back screw (4) serves as a handle for the user to determine the rotation of the shaft (1).
12. Device (14) according to any of the claims 6 to 11, wherein a hole or throughbore (13) is provided to insert an optional tool in order to prevent the shaft (1) from turning as the tip screw (7) or the back screw (4) is tightened.
Description:
TJ UTVECKLING AB DEVICE FOR FASTENING TURNING CUTTERS Technical Field The present invention relates to a device for holding turning cutters as they are ground against a rotating grindstone.

Background of the invention Grinding and sharpening of cutting and scraping tools have for long times been performed on grindstones. One major problem with grinding cutting and scraping tools is that the edge angle preferably should be kept the same during a tool's lifespan. It is also preferable that the bevels are as straight as possible.

The grindstone is driven by-an electrical motor, which has its rotational speed geared down to a lower rotational speed. Usually, the grindstone is wetted during operation by lowering a portion of it into a drum of water or any other suitable liquid. The wetting of the grindstone reduces the risk that any portion of the object that is to be ground overheats, with resulting losses of hardening properties. The rotational speed of the grindstone is adapted so that the liquid on the grindstone does not get thrown off by the centrifugal force, but still is high enough to allow proper grinding.

In order to make it easier to obtain an appropriate edge angle with straight bevels, several different holders have been used to hold the object that is to be ground.

Swedish Patent 510 362 is one example of such an assembly to correctly hold objects that are to be ground.

Not all edges on cutting tools are straight. Such non-straight edges are generally more difficult to grind, while they must be continuously moved during the grinding operation, since the edge otherwise will alter in shape

compared to the original shape. The assembly in the afore- mentioned Swedish patent largely overcomes several of the difficulties with grinding curved surfaces.

One major problem remains however: although the in- vention has proven excellent for grinding large objects, it is not possible to properly grind small objects, such as interchangeable turning cutters.

The Invention The present invention aims to make it possible to fasten objects too small for an ordinary grinding jig. The invention should be used in conjunction with a sleeve of the type described in Swedish patent 510 362, and it com- prises a shaft with a front end and an opposite back end.

On the front end, there is fastening means for turning cutters with various fastening hole sizes. During opera- - tibn ; the-back end of the shaft--shoul-d be rotatably engaged with the sleeve from the aforementioned Swedish patent or any corresponding device. Withholding means may be used to prevent the shaft from escaping the sleeve after the two pieces have been combined.

The rotatable connection with the sleeve makes it possible to grind not only straight edges, but also curved edges by turning the shaft with the attached cutter accord- ing to the curvature of the edge. The rotatability also makes it possible to regrind a turning cutter to a new edge shape.

The fastening means makes it possible to fasten turning cutters with various fastening hole diameters, without any inserts. Instead, only a tip screw is used to press the turning cutter towards the surface on a shoulder or the tip of the shaft, depending on the fastening hole diameter on the turning cutter.

A grinding operation starts with the user setting the distance between the support bar and the grindstone. This

is done to ensure that the bevel angle is set to an appro- priate amount. After the correct distance is set, the bevel angle is fix, which allows the user to concentrate on the grinding itself, and not to hold the object to be ground at the correct angle during the grinding.

Brief description of the attached figures.

The attached figures show one at present preferred embodiment of the present invention. The figures are at- tached with the sole purpose of making the invention more understandable, and are not limiting the scope of the in- vention.

Fig. 1 is a side view showing a grinding jig with a device according to the present invention Fig. 2 is a side view of parts of the device of Fig.

1 showing mounting of a shaft in a sleeve.

Fig. 3 and 4 are side views showing how turning cutters with small (Fig. 3) and large (Fig. 4) fastening holes, respectively, are mounted on the device of Fig. 1 and 2.

Detailed description of a preferred embodiment Fig. 1 shows a conventional grindstone 8 with a sup- port bar 9 rigidly placed in front of it. On the support bar 9 there is a sleeve 2 slidingly engaged to the support bar 9. The sleeve 2 is slidable along the longitudinal axis of the support bar 9. The support bar 9 is positioned at a predetermined distance from the grindstone 8 before the grinding operation commences, hence determining the correct bevel angle. The two arrows in figure 1 shows how the position of the support bar is set before the grinding commences.

The sliding engagement to the support bar 9 makes it possible to move the object to be ground back and forth during the operation, which makes it possible to wear the

grindstone evenly. In the sleeve 2, a shaft 1 according to the present invention is rotatably mounted. On the tip 3 of the shaft 1 are fastening means for receiving a turning cutter that is to be ground provided. On an appropriate distance from the tip 3, there is a circumferential pro- jection 5 that restricts the shaft 1 from sliding too far into the sleeve 2. The appropriate distance in this case means the distance that leaves enough shaft length that is inserted in the sleeve 2. The means for preventing the shaft from sliding too deep in the sleeve 2 can also be embodied in other ways without deviating from the scope of this invention, e. g. the sleeve 2 may contain a projection that projects inwards to narrow the inner diameter.

In order to be able to fasten turning cutters 15 with various fastening hole diameters, there is a shoulder 6 provided on the tip 3 of the shaft 1. For cutters 15 with small diameters, the cutter-15 rests upon the front end surface 10 of the shoulder 6 and is guided by the tip screw 7. For cutters 15 with large hole diameters, the cutter 15 is guided by the circumferential outer surface 12 of the shoulder 6 and rests upon the flat surface 11 on the tip 3 of the shaft 1.

As mentioned, the support bar 9 and the sleeve 2 are parts already known. Their basic function are to hold an object that is to be ground rigidly, so that the user can concentrate on grinding the object evenly and not have to concentrate on getting the correct bevel angle.

Usually, the object that is to be ground is held by a tool support member, but this member does not allow turning cutters 15 to be properly fastened. To allow for the grind- ing of turning cutters 15, the shaft 1 of the present in- vention is inserted in the sleeve 2 and axially locked in the sleeve 2 by tightening the back screw 4 on the back end of the shaft 1 (see Fig. 2). The turning cutter 15 can then

be fastened on the tip 3 of the shaft 1 by the fastening means provided on the tip 3 of the shaft 1.

The back screw 4 has a further task, except from withholding the shaft in the sleeve 2; when tightened, the head of the back screw 4 works as a handle to let the user determine the rotation of the shaft 1.

Different types of turning cutters 15 with various fastening hole diameters can be fastened by the fastening means in accordance with the present invention as follows, with reference to figures 3 and 4: 1. Turning cutters 15 with small fastening hole dia- meter (e. g. below 8 mm) rests upon the front end surface 10 of the shoulder 6 and are guided by the tip screw 7.

2. Turning cutters 15 with large fastening hole dia- meters (e. g. 8-10 mm) rests upon the front end surface 11 of the-tip 3 of the shaft 1 and are guided by the outer circumferential surface 12 on the shoulder 6.

For both the turning cutters 15 with small and large diameter fastening holes, the cutter 15 is fastened by means of tightening the tip screw 7 firmly. The fastening means can however be varied without falling out from the scope of the present invention. For example, the turning cutter 15 can be fastened by a nut engaging a threaded rod extending from the shaft.

To avoid that the shaft 1 turns as the back screw 4 or the tip screw 7 is tightened, there is a hole or throughbore 13 provided on the shaft 1 to insert an optional elongate tool, with a diameter smaller than the hole or throughbore 13, in the hole or troughbore 13, to be able to keep the shaft 1 from rotating as the tip and back screws 7,4 are tightened. The avoiding of shaft 1 turning can be provided in numerous ways without deviation from the scope of the present invention, e. g. it can be accomplished

by providing flattened surfaces on the shaft 1, allowing for a wrench to keep the shaft 1 in a non-rotated position.

Further, the inner diameter of the sleeve 2 can be tight- ened to let the internal friction between the sleeve 2 and the shaft 1 prevent rotation.

The circumferential projection 5 is slidingly engaged to one end of the sleeve 2, and prevents the shaft 1 from sliding in too deep in the sleeve 2. In the preferred em- bodiment, the circumferential projection 5 is in form of a clamp ring in a circumferential groove, but any kind of projection that prevents the shaft 1 from sliding too far into the sleeve 2 can be used without deviating from the scope of the present invention.

The back end of the shaft 1 is provided with means to prevent the shaft 1 from escaping the sleeve 2 once it is inserted. In the preferred embodiment, an internal thread at the longitudinal axis of the shaft 1 is engaging a back screw 4 with a like external thread. The head of the back screw 4 has a larger diameter than the portion of the shaft 1 that is rotatably engaged with sleeve 2, and the inner diameter of the sleeve 2, thereby preventing the shaft 1 to slide out from the sleeve 2. The shaft 1 can be prevented from sliding out from the sleeve 2 in a variety of ways, e. g. by means of spring locks, barbs, clamp rings etc, without deviating from the scope of this invention.