GB2046145A

GB2046145A - Machine for Sharpening Cutting Tools or Grinding Other Materials

Info

Publication number: GB2046145A
Application number: GB8012245A
Authority: GB
Original assignee: Hanning Elektro Werke GmbH and Co KG
Current assignee: Hanning Elektro Werke GmbH and Co KG
Priority date: 1979-04-14
Filing date: 1980-04-14
Publication date: 1980-11-12
Also published as: GB2046145B; FR2453711A1; SE8002660L; FR2453711B1

Abstract

A machine for sharpening cutting tools or grinding other material comprises a wetted grinding disc (4) having a cylindrical peripheral surface and an electric motor (3) for driving the grinding disc (4) through a friction wheel (9) located on the rotor shaft (7) of the motor (3) and in engagement with the grinding disc (4). The machine includes a one-piece grinding rest (15) having a plurality of rest surfaces (16, 17). The rest is vertically adjustably mounted on the top of a water box (5) housing the grinding disc by resilient toothed tongues (21) engaging mating surfaces (22) on the water box. <IMAGE>

Description

SPECIFICATION Machine for Sharpening Cutting Tools or Grinding Other Materials The invention relates to a machine for sharpening cutting tools or grinding material and which has a grinding disc and having a cylindrical peripheral surface wetted with water and an electric motor driving the grinding disc. In machines such as this, the grinding disc may only rotate at low speed in order that the material for grinding which is to be processed may be sharpened perfectly. The water carried along by the grinding disc at its periphery should cool down the material for grinding and prevent it from softening without being centrifuged away by the grinding disc. Therefore the electric motor had in the past to be equipped with a reduction gearing reducing its rotary speed.

The invention seeks to create a construction which is more favourable in terms of cost and which does not require reduction gearing.

According to the invention, there is provided a machine for sharpening cutting tools or grinding other materials comprising a grinding disc defining a cylindrical peripheral surface, means for wetting said grinding disc, an electric motor, for driving the grinding disc wherein a friction wheel is mounted on the rotor shaft and is in driving engagement with the grinding disc.

Thus, in relation to the grinding disc, the friction wheel should have a diameter at which the rotary speed of the grinding disc required for grinding is achieved and at which a film of water forms on the periphery of the grinding disc.

The invention recommends two different methods of movable mounting of the grinding disc. According to these, the grinding disc axle should either slide in vertical guide slots in the machine casing or the movable mounting of the axle may be effected by a rocker hinged to the machine casing. In both cases it is advisable to fix the axle of the grinding disc in the guide slots of the machine casing or in the openings in the bearing of the rocker and/or to fix the mounting of the rocker in the machine casing in a lockable manner. Moreover, there are advantages in manufacture if the axle of the grinding disc and the tensioning flanges which serve to fix the grinding disc on its axle are manufactured as a one piece injection-moulded plastics member.

The grinding disc may rotate in a water box which is open at the top and accommodates water, a rest being placed on the water box and having several rest surfaces. It may be formed in one piece and may surround the region of the grinding disc projecting out of the water box.

These rest surfaces may be inclined tangentially to the peripheral surface of the grinding disc at various grinding angles. In addition, at least one rest surface may have transverse furrows arranged in steps. Moreover, it is advantageous if the grinding rest on the water box is displaceable with respect to the grinding disc in terms of height and this may be achieved by forming an adjustable mounting of the grinding rest on the water box of preferably toothed and resilient tongues arranged on the grinding rest and of matching elements which are also toothed and cause locking against the water box. In order to displace the grinding rest the toothed and resilient tongues may be provided with webs or projections actuable by finger pressure for movement of the resilient tongues.

The versatility of the grinding rest which at the same time constitutes a cover for the water box may be increased still further by arranging for the grinding rest to be removable from the water box and arranged to be locatable in two positions on the water box having been turned through 1800.

Thus the rest surfaces of the grinding rest can be used from both directions of rotation of the grinding disc whereby the position of the grinding disc can be matched to the respective material to be ground.

The most essential advantage of the design in accordance with the invention lies in that the very expensive reduction gearing which was previously usual is no longer essential. This saving is not only advantageous in terms of the manufacturing costs of the machine but also permits a reduction in the construction size so that the machine which is intended more particularly for domestic use or for the handyman is more compact. The simple mounting of the grinding disc furthermore makes it possible to dispense with expensive tensioning means for the grinding disc by producing the axle of the grinding disc and the tensioning flanges as a common injection-moulded plastics member and this is favourable in cost.

Similarly several advantages may be achieved for the application of the newly developed machine. With a friction wheel used to drive the grinding disc and the movable mounting of the grinding disc in a vertical direction, constant force transmission from the electric motor to the grinding disc can be guaranteed which is true even in the case of uneven wear. When grinding objects, an increase in pressure occurs and so does a correspondingly better drive action; on the other hand the grinding disc can slip on the friction wheel if it should be blocked for any reason. This last feature constitutes a reduction in the danger of an accident.

In addition it is to the advantage of the user of the machine that the preferred grinding disc which does not require lubrication or maintenance as regards its mounting may be exchanged without auxiliary means because its axle and/or the rocker retaining it only rests in place in each case. Cleaning of the water box of any grit or dirt may be very much easier by taking out the grinding disc easily from the water box or pivoting it out of the water box with the aid of the rocker. Finally, the mode of construction in accordance with the invention may provide further savings in energy since previous gearing losses which were particularly high because of the use of worm gears are removed and the degree of efficiency of the machine is also considerably improved.

The invention will now be described in greater detail, by way of example, with reference lo the drawings, in which.

Figure 1 shows a longitudinal section through a machine in accordance with the invention for sharpening cutting tools; Figure 2 shows an end elevation of the machine of Figure 1; Figure 3 shows an end elevation of a modified machine; Figure 4 shows an end elevation similar to Figure 2 but having a grinding rest located on the water box of the machine; Figure 5 shows the grinding rest of Figure 4 during adjustment in height, and Figure 6 shows the grinding rest when locked onto the water box.

In accordance, with Figure 1, the machine illustrated therein comprises a machine casing 2 equipped with a base plate 1, an electric motor 3 housed inside the machine casing 2 and a grinding disc 4 which rotates in water 6 accommodated in a water box 5 of the machine casing 2. The grinding disc 4 is driven by the electric motor 3 whose rotor shaft 7 projects into the water 6 through a seal 8 and carries a friction wheel 9 of small diameter at that end thereof. The grinding disc 4 is supported on this friction wheel 9 and is mounted for movement in a vertical direction, the-rocket 10 which can be seen from Figure 2 serving for this purpose. However vertical guide slots 11 may be provided in the water box 5 (Figure 3) for this purpose and the grinding disc axle 12 then slides in these slots.

Lateral tilting of the grinding disc 4 is prevented by the rocket 10 which is pivoted on the water box 5 of the machine casing 2 as is apparent from Figure 2. Moreover, with the aid of the rocker, the grinding disc 4 may be pivoted out of the water 6, in the manner shown, thus facilitating easy cleaning of the water box 5.

Both in the embodiment of Figures 1 and 2 and in the simplified construction of Figure 3 the axle 12 of the grinding disc is located in a retainable manner in the bearing openings 13 of the rocker 10 retaining it or in the guide slots 1 The same is true for mounting of the rocker 10 on the water box 5 of Figure 2. These measures make it possible to exchange the grinding disc 4 easily.

Since the axle 12 of the grinding disc does not have any drive forces to be transmitted to the grinding disc 4, then it may be manufactured, together with the tensioning flanges 14 serving to fix the grinding disc 4 to the grinding disc axle 12 as a single piece injection-moulded member of plastics material. This simplified method of manufacture has an advantageous effect on the manufacturing costs of the machine as does the omission of the reduction gearing which was previously usual.

According to Figure 4 a grinding rest 15 in one piece and manufactured preferably from plastics is placed on the water box 5 of the machine casing 2 and the grinding disc 4 is surrounded by this grinding rest 15 in its region projecting out of the water box 5. The grinding rest 15 which at the same time forms a cover for the water box 5 should serve as an aid to grinding for guiding the material which is to be ground to the grinding disc 4. Thus its rest surfaces 16 and 17 are inclined at an angle a orb which is matched to the respective materials to be ground for example a knife 18.

tangentially of the cylindrical peripheral surface 19 of the grinding disc 4. An additional aid to grinding are the transverse furrows 20 arranged like steps in the rest surface 16.

The compatibility of the grinding overlay 1 5 to the respective material to be ground is increased still further by making the grinding rest 15 on the water box 5 adjustable in height with respect to the grinding disc 4. The adjustability of the grinding overlay 15 is achieved by forming its mounting in accordance with Figure 5 and 6 from toothed and resilient tongues 21 arranged on the narrow sides of the grinding rest 1 5 and from mating elements 22 which are also toothed and cause the mounting to lock on the water box 5.

Thus the resilient tongues 21 located on the grinding rest 15 have ridges 23 susceptible to finger pressure at their surface by means of which the resilient tongues 21 may be moved with respect to each other in accordance with Figure 5 and thus may be released from their locked position against the toothed mating elements 22.

According to whether the grinding rest 1 5 is to be raised or lowered, the resilient tongues 21 may lock higher or lower into the mating elements 22 as is apparent from Figure 6.

Similarly it is possible in the manner described previously to remove the grinding rest 15 from the water box 5, as necessary in order to fill it with water 6 or to enable the rest to be turned through 1800 and replaced on the water box 5.

Thus the position of the overlay surface 1 6 and 17 with respect to the grinding disc 4 has been changed again so that they may be used in reverse to the direction of rotation of the grinding disc 4 as is advisable in many cases.

It will be understood that the above description of the present invention is susceptible to various modification changes and adaptations.

Claims

1. A machine for sharpening cutting tools or grinding other materials comprising a grinding disc defining a cylindrical peripheral surface, means for wetting said grinding disc, an electric motor, for driving the grinding disc wherein a friction wheel is mounted on the rotor shaft and is in driving engagement with the grinding disc.

2. A machine as claimed in Claim 1, wherein the diameter of the friction wheel is so related to the diameter of the grinding disc that the rotary speed of the grinding disc required for grinding and at which a film of water is formed on its periphery is achieved.

3. A machine as claimed in Claim 1, or 2, wherein the axle of the grinding disc is mounted in vertical guide slots of a machine casing for guiding vertical movement of the grinding disc.

4. A machine as claimed in Claim 1 or 2, wherein the axle of the grinding disc is mounted on a rocker pivotably mounted on a machine casing to permit movement of the grinding disc.

5. A machine as claimed in Claim 3, wherein the axle of the grinding disc is fixed in lockable manner in the guide slots of the machine casing.

6. A machine as claimed in Claim 4, wherein the axle of the grinding disc is fixed in lockable manner in bearing openings of the rocker.

7. A machine as claimed in Claim 4 or 6, wherein the mounting of the rocker is fixed in lockable manner in the machine casing.

8. A machine as claimed in any one of Claims 1 to 7, wherein the axle for the grinding disc and tensioning flanges serving to fix the grinding disc on the grinding disc axle are formed as a single piece injection-moulded plastics member.

9. A machine as claimed in Claim 1, wherein a water box open at the top, accommodating water and in which the grinding disc rotates is provided, a one piece grinding rest having several rest surfaces being located on the water box to surround a region of the grinding disc projecting out of the water box, the rest surfaces being inclined tangentially to the peripheral surface of the grinding disc at various grinding angles.

10. A machine as claimed in Claim 9, wherein at least one rest surface of the grinding rest has transverse furrow arranged like steps.

1 A machine as claimed in Claim 9 or 10, wherein the said grinding rest is displaceable in terms of height with respect to the grinding disc.

12. A machine as claimed in Claim 1 wherein the displacing means comprises resilient tongues arranged on grinding rest and mating elements on the water box.

13. A machine as claimed in Claim 12, wherein the resilient tongues and the mating elements each have a plurality of teeth.

14. A machine as claimed in Claim 12 or 13, wherein webs or projection are provided on the resilient tongues and movable by finger pressure for movement of the resilient tongues.

15. A machine as claimed in any one of Claims 9 to 14, wherein the grinding rest is removable from the water box and is locatable on the water box in two positions turned through 1 800.

16. A machine for sharpening cutting tools or grinding other materials substantially as described herein with reference to the drawings.