GRINDING DEVICE FOR GRINDING SCISSORS

Abstract: Grinding fixture for grinding scissors by means of a ro­ tatable grindstone (1) using an adjustable support arm (3) arranged at the grindstone base and extending transversely of the grindstone (1) in parallel with the axis thereof. Accord­ ing to the invention the grinding fixture comprises a support plate (4) movably and rotatably fixable to the support arm (3), a first clamping plate (7) abutting on the support plate (4) freely movably as well as at least one second clamping plate (10) having a clamping edge. One blade (15) of a pair of scissors to be ground can be clamped between the clamping edge and the first clamping plate (7) be means of one or more screws (12, 13).

Description: This invention relates to a grinding fixture for grind­ ing scissors in accordance with the preamble of claim 1 and is for instance intended for use in grinding machines provided with a grindstone and equipped with a fixed support of the type described in Swedish Patent Application No. 8306325-5. So far there has been no good aid for grinding scissors by means of a grindstone. The blades of the scissors can be plane, be straight or arcuately tapering longitudinally, have a cross section that is plane or like a partial circle, and have an edge which is straight or convex lengthwise of the blade. In addition, the cutting angle is very sharp in scissors. However, it is possible by means of this invention, as it is apparent from the characterizing portions of the claims, to adjust and move the edges of the scissors - one at a time -­ across the grindstone by means of a holder or grinding fixture so that the best possible result is obtained independently of the form of the blades of the scissors. Also an unexperienced person can grind all types of scissors simply and quickly by means of the grinding fixture of the invention. The invention will be described in greater detail in the form of an example with reference to the drawing wherein Fig. 1 is a schematic partial view of a pair of scissors clamped in a fixture according to the invention, Fig. 2 shows a cross section of the fixture according to Fig. 1 and Fig. 3 shows a longitudinal section of the fixture shown in Fig. 1. In the figures 1 denotes a grindstone and 2 a support fixedly secured to the grinding machine in the form of a yoke with an arm 3 extending in parallel with the axis of the grindstone 1. The grinding machine with support and arm is known per se and is no part of the invention, and therefore this will not be described more closely but it is referred to said Swedish Application 8306325-5 in this connection. The grinding fixture consists of a support plate 4 which is bent at right angles and carries a welded pipe or a bushing 5, by means of which the support plate is supported by the arm 3 so that it can be moved and turned. A threaded, through hole is made in the wall of the bushing 5 in which a screw provided with a knob is threaded. The knob has the reference numeral 6. By means of the knob and the screw attached to this the sup­ port plate 4 can be fixed in a suitable position along the arm 3 and at the intended angle defined by the edge angle of the pair of scissors to be ground. A first clamping plate 7 which in the example shown has a layer of low-friction material 8, for example teflon®, on the side facing the support plate 4, abuts on the support plate 4 freely movably. Moreover, the first clamping plate 7 has two threaded holes 9 in the example shown. Two other clamping plates 10 have through holes 11 corresponding to the threaded holes 9, through which set screws 12 pass. In the respective second clamping plate 10 a locking screw 13 provid­ ed with a wheel is arranged to be screwed into the plate at some distance from the set screws 12. In the example shown the threads of the screw 13 are made in a threaded bushing 14 ar­ ranged in the respective plate 10. The head of the respective set screw 12 has a partly spherical inside resting in a corresponding partly spherical seat of the second clamping plate 10. The distance between the second clamping plates 10 and the first clamping plate 7 can be optionally adjusted in dependence on the thickness of the blade 15 of the scissors to be ground by means of the screws 12. In Fig. 3 there is shown a blade of a pair of scissors, the thickness of which decreases towards the tip and it is clearly apparent from the figure how different an adjustment is required of the distance of the second clamping plates 10 from the first clamping plate 7 is required. By the partly spherical head form of the screw 12 and its coacting seat of the respective clamping plate 10 these can adjust themselves obliquely and independently of one another relative to the first clamping plate 7. Consequently there is a possibility for a complete adaptation of the clamping plates to the form of the blade of the pair of scissors, the edge of which is to be ground. As is clearly apparent from Fig. 2 the free end of the locking screw 13 engages the first clamping plate 7 and due to the fact that the set screw 12 at the respective second clamp­ ing plate 10 is arranged in the vicinity of the region where the blade of the pair of scissors is adapted and the locking screw 13 is arranged on the opposite side relative to the blade and spaced from the set screw 12, the locking screw 13, when turned, will swing the second clamping plate 10 from the first clamping plate 7 with the set screw 12 as turning point and consequently lock the blade 15 placed between the edge portions of the clamping plates 10 and 7. By this "lever principle" it is possible to attain very great locking forces for the blade of the pair of scissors. In order to achieve defined locking ranges of the blade of the pair of scissors the respective second clamping plate 10 at each end of the locking edge area is provided with a downwardly directed flange 16 (see Fig. 3). These flanges can be simply obtained by for instance milling the central area in the respective plate. In order to control the second clamping plates 10 relative to the first clamping plate 7 a pair of guide pins shematically shown in Fig. 1 and designated by 17 are attached to the respective plate 10. These pins extend freely movably through the corresponding holes or openings in the first clamping plate 7. Moreover, helical compression springs can be arranged around the respective pin 17 between the plates 10 and the plate 7, which springs tend to separate the plates 10 and the plate 7 automatically which makes it easier to place the blade of the pair of scissors between the edge portions of the plates. Thus, by adjusting the screws 12 the fixture can be ad­ apted to the thickness of the current blade of the pair of scissors and said blade is clamped in the fixture when tight­ ening the locking screws 13. Thus, the clamping plates 10 will adapt themselves automatically to the form of the relative blade independently of whether its cross section is conical or in the form of a partial circle or if it is conical longitud­ inally. The support plate 4 is locked by means of the screw 6 at the arm 3 with the current edge angle of the pair of scis­ sors, and the part of the fixture formed by the clamping plates 7 and 10 can now be moved backwards and forwards sup­ porting against the plate 5 while the edge of the pair of scissors is being ground. In this way the motion can be simply adapted so that the possibly arcuate edge of the pair of scis­ sors is in contact with the screw all the time. The low fric­ tion material 8 makes this motion easier. However, it is to be understood that this low friction material is not necessary but can be omitted. A fixture with two other clamping plates 10 has been de­ scribed above, but of course more than two such clamping plates can be used. Of course it is possible, for example when grinding only small pairs of scissors, to use a fixture having only one second clamping plate 10. The shapes of the support plate 4, the first clamping plate 7 and the second clamping plates 10 can of course vary and deviate from the shapes shown here. Moreover, the guide pins 17 can be attached to the first clamping plate 7 instead of the plates 10.

Claims: 1. Grinding fixture for grinding scissors by means of a rotatable grindstone (1) using an adjustable support arm (3) arranged at the grindstone base and extending transversely of the grindstone (1) in parallel with the axis thereof as well as a support plate (4) movably and rotatably fixable to the support arm (3), characterized by a first clamping plate (7) abutting on the support plate (4) freely movably and at least one second clamping plate (10) having a clamping edge, one blade (15) of a pair of scissors to be ground being clampable between the clamping edge and the first clamping plate (7) by means of one or more screws (12, 13). 2. The grinding fixture of claim 1, character­ ized in that the clamping edge of the second clamping plate (10) has flanges (16) arranged in spaced relationship, facing the blade (15) of the pair of scissors and extending transversely of the blade. 3. The grinding fixture of claim 1 or 2, char­ acterized in that two or more second clamping plates (10) are arranged beside each other on the first clamping plate (7) in order to adapt themselves each and clamp their part of the blade (15) against the first clamping plate (7). 4. The grinding fixture of any one of the preceding claims, characterized in that the first clamp­ ing plate (7) and the second clamping plate (10) are connected to each other by means of a set screw (12) immediately at the pair of scissors adjusting the mutual distance of the plates (7, 10). 5. The grinding fixture of claim 4, character­ ized in that a locking screw (13) is arranged to be screwed into a threaded hole (14) extending through the first or second clamping plate (7 and 10, respectively), said hole being located on the opposite side of the set screw (12) re­ lative to the blade (15) of the pair of scissors to be ground, and that one end of the locking screw (13) engages the second and first clamping plate (7, 10), respectively. 6. The grinding fixture of any one of the preceding claims, characterized in that the first or the second clamping plate (7 and 10, respectively) has at least one fixed guide pin (17) coacting with an aperture arranged in the coacting clamping plate (7, 10) and that a compression spring is arranged between the plates in connection with the guide pin (17).

Inventors: JANSSON, TORGNY
Applicants: TORMEK AB
Application year: 1987
Main classification: B24B3
IPC codes: B24B3