The present disclosure relates a grinding jig for a blade tool. The present disclosure also relates to a grinding machine with a grinding jig for a blade tool.
Grinding of blade tool, such as knives, which has edges with opposite edge bevels is typically made by clamping the blade tool in a grinding jig and moving the tool across a revolving grindstone. When the edge bevel on the first side of the tool has been sharpened, the grinding jig is turned over and moved in opposite direction across the grindstone so that edge bevel on the second side of the blade tool is sharpened.
While proven reliable in grinding operations, the conventional grinding jig has a drawback in that blade tool is not centered in the grinding jig. This has the effect that the angle between the blade and the grinding stone changes when the grinding jig (after completed grinding the first edge bevel) is turned over to grind the second edge bevel of the blade. The deviation of the edge bevel angles appears to increase with increasing blade thickness.
A further drawback with the conventional grinding jig is that it has shown to produce convex edges. The strength of the edge of the blade is reduced with increasing convexity.
Thus, there is a need for an improved grinding jig for blade tools.
Consequently, it is an object of the present disclosure to provide a grinding jig for blade tool that solves at least one of the problems of the prior-art.
In particular, it is an object of the present disclosure to provide a grinding jig which achieves a strong edge of a blade tool after grinding.
In addition, it is an object of the present disclosure to provide a grinding jig for a blade tool which achieves a minimum of difference between the angles of the edge bevels of the blade tool after grinding.
A further object of the present disclosure is to achieve a simple, yet robust, and easy to handle grinding jig for blade tools providing a minimum of difference between the angles of the edges of the blade tool after grinding.
According to the present disclosure, at least one of these objects is met by a grinding jig for holding a blade tool having an edge in a grinding machine, said grinding machine having a grindstone and a support bar for supporting a grinding jig, said grinding jig comprising:
The front end and rear end abutment surfaces allows the grinding jig to be moved in a controlled manner back and forth relative the support bar during grinding of the blade. Practical trials have shown that this controlled movement, limited between the front and rear abutment parts, results in that a convex bevel is achieved on the edges of the blade tool during grinding. Such convex edges are proven to be very strong.
It is appreciated that the grinding jig also may be moved back and forth along the support bar, in direction traverse to the longitudinal center axis Y of the grinding jig.
According to an alternative, the grinding jig may comprise a first and a second separate grinding jig half which are mutually facing each other and respectively comprises a clamp half and an elongate support portion half The grinding jig may thereby be arranged such that the first and the second grinding jig half may be releasably forced towards each other to hold a tool blade between the first and a second clamp half. The first and second grinding jig half comprise a respective front abutment half and a respective rear abutment part, wherein the front abutment halves and the rear abutment halves are arranged spaced apart from each other on the respective support portion half and configured for abutment with a support bar of a grinding machine.
Thus, the grinding jig according to this alternative comprises two separate jig halves which each include a clamp half and a support portion half. This has the effect that when a blade tool is clamped between the jig halves, both jig halves will be on the same distance from the center of the blade tool regardless the thickness of the blade. In particular, the first and the clamp will be on the same distance from the center of the blade and the first and second support portion will be on the same distance from the center of blade. Therefore, in a grinding operation there will be no, or negligible, change in angle between the blade and the grind stone regardless whether the first edge bevel or the second edge bevel of the blade is ground.
Further alternatives and advantages are disclosed in the appended claims and the following description.
The grinding jig according to the present disclosure will now be described more fully hereinafter. The grinding jig according to the present disclosure may however be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those persons skilled in the art. Same reference numbers refer to same elements throughout the description.
In a grinding operation, as schematically indicated in
The first and the second grinding jig half are arranged mutually facing each other. That is, such that the contact portion 111, 121 of the respective grinding jig half 101, 102 faces each other.
The grinding jig 100 may further comprises an actuator 130 which is arranged to releasably force the first and the second grinding jig half 101, 102 towards each other. The clamping halves 110, 120 of the respective first and second grinding jig half may thereby be brought together with sufficient force to securely hold a portion of blade tool. The actuator 130 is coupled to the first and the second grinding jig half such that it may bring and hold the first and second grinding jig half together and may release the first and second grinding jig half from each other. In the disclosed embodiment, the actuator 130 may be a screw which extends through an opening 131 in the first jig half 101. The screw may have a ring-shaped shoulder 132 that rests on the first grinding jig half 101. The end of the screw 133 has a threaded portion which engages a threaded opening 122 in the second grinding jig half 102. Turning of the actuator 130 in one direction forces the first and second grinding jig half 101, 102 towards each other. Turning of the actuator 130 in opposite direction releases the tension between the first and second grinding jig half 101, 102 and allows them to move away from each other.
A resilient member 150 may be arranged between the first and second grinding jig half 101,102 for biasing the grinding jig halves away from each other.
The actuator 130 for releasably forcing the first and the second grinding jig half 101, 102 towards each other may be realized in other modes. For example, the actuator may be cam-lever arrangement or a ratchet arrangement.
Each grinding jig half 101, 102 may further comprise a respective front abutment half 163, 164 and a respective rear abutment part 165, 166. The front abutment halves 163, 164 and the rear abutment halves 165, 166 are arranged spaced apart from each other on the respective support portion half 161, 162. The front and rear abutment halves protrude perpendicular from the respective support portion half 161 and 162 and may be in the form of half discs.
The elongated support portion 160 comprises a front end abutment surface 170 and a rear end abutment surface 180. The front and rear end abutment surfaces 170, 180 are spaced apart such that a portion of a support bar of a grinding machine may be received there between. The front and rear end abutment surfaces 170, 180 are thereby spaced apart sufficiently to allow the operator to move the grinding jig 100 back and forth relative the support bar 350.
In detail, the front and rear end abutment surfaces 170, 180 are aligned along a longitudinal center axis Y of the grinding jig 100. The axis Y extends through the front end of the grinding jig, the clamp halves 110, 120, the support portion 160 and the rear end of the grinding jig. The rear end abutment surface 180 is thereby arranged after the rear end 190 of the grinding jig and the front end abutment surface 170 is arranged after the rear end abutment surface 180 and the clamp halves 110, 120 are arranged after the front end abutment surface 170.
The front and rear end abutment surfaces may extend perpendicular from the support portion 160 and around its circumferential and may thereby have the form of discs. The distance, by which the front and the rear end abutment surfaces are spaced apart is selected such that the distance is greater than the diameter of the support bar of a grinding machine and such that it allows a slight movement back and forth of the grinding jig 100 when it is supported on the support bar. For example, the distance between the front and rear end abutment surfaces is 2-5 cm. The height of the front and rear end abutment surfaces 170, 180 is selected such the support bar of a grinding machine is prevented from passing beyond the front and rear end abutment surfaces 170, 180 when the grinding jig is 100 is moved back and forth relative the support bar. For example, the height is 1-2 cm.
The rear end of the support portion 160 may terminate in a handle portion 190 which is configured to be griped by an operator of the grinding jig.
The grinding jig may be split into two separate halves that are on opposite sides of a central plane x extending through the center of the grinding jig.
The advantage of the spaced apart front and rear abutment surfaces 170, 180 is that they make possible to achieve convex edge bevels during grinding of bladed tools.
The function of the grinding jig 100 according to the present disclosure is in the following described with reference to
Simultaneously, the operator may move the grinding jig 100 relative the support bar 350 back and forth in direction parallel with the longitudinal axis Y of the grinding jig 100 as indicated by arrow B. In other words, parallel with the rotation direction R of grindstone 310.
The movement back and forth of the grinding jig 100 relative the support bar 350 in direction parallel with its longitudinal axis Y is restricted by the front and rear end abutment surfaces 170, 180 of the grinding jig 10. The rear end abutment surface 180 there by restricts movement of the grinding jig in one direction, e.g. away from the support bar 350, The front end abutment surface 170 restricts movement in opposite direction, e.g. towards the support bar 350.
The movement back and forth of the grinding jig 100 in direction parallel with its longitudinal axis Y results in an edge with convex edge bevels after grinding. Edges with convex edge bevels are stronger than edges with concave or straight edge bevels.
The front and rear end abutments surfaces 170, 180 thereby assists the operator to control the movement of the grinding jig 100 such that a beveled edge 210 is achieved on the bladed tool 220. The distance between the front and rear abutment surfaces 170, 180 controls the shape of the final edge and may be selected on basis of practical trials.
Although a particular embodiment has been disclosed in detail this has been done for purpose of illustration only, and is not intended to be limiting. In particular, it is contemplated that various substitutions, alterations and modifications may be made within the scope of the appended claims.
Number | Date | Country | Kind |
---|---|---|---|
1950422-4 | Apr 2019 | SE | national |