EP0072811A1

EP0072811A1 - Tool grinding machine

Info

Publication number: EP0072811A1
Application number: EP19820900397
Authority: EP
Inventors: Hans Frederik Birger HÖGFORS
Original assignee: Estate Of Hogfors Hans Frederik Birger (deceased)
Current assignee: Estate Of Hogfors Hans Frederik Birger (deceased)
Priority date: 1981-01-26
Filing date: 1982-01-26
Publication date: 1983-03-02
Also published as: SE8100442L; SE432216B; WO1982002507A1

Abstract

Machine a aiguiser servant a l'aiguisage de meches, d'outils de tour et de tarauds filetes ou analogues possedant une plaque support (8) tournant un plan parallele au plan d'une roue d'aiguisage (3) et reglable dans plusieurs inclinaisons variables par rapport a un plan perpendiculaire au plan du mouvement de pivotement. La plaque de support possede une rainure de guidage (9) dans laquelle coulissent sur des guides des patins mobiles et interchangeables servant a saisir les outils en question. La plaque support est reglable et les differents patins sont concus de maniere a pouvoir etre regles respectivement pour executer l'aiguisage desire de meches, d'outils de tour, de tarauds ou analogues.Sharpening machine for sharpening bits, lathe tools and threaded taps or the like having a support plate (8) rotating a plane parallel to the plane of a sharpening wheel (3) and adjustable in several inclinations variables with respect to a plane perpendicular to the plane of the pivoting movement. The support plate has a guide groove (9) in which movable and interchangeable pads slide on guides for gripping the tools in question. The support plate is adjustable and the different pads are designed so that they can be adjusted respectively to execute the desired sharpening of bits, lathe tools, taps or the like.

Description

Tool grinding machine BACKGROUND OF THE INVENTION AND PRIOR ART

Twist drills are ground either with cone mantle shaped clearance surfaces or with planar clearance surfaces. During grinding, they are normally clamped in a chuck which holds the drill during grinding so that the drill after rotation for half a revolution may be ground on the other edge. It is also known to clamp the drill between two jaws which are tightened by a yoke and a clamp screw. Machines are also known, wherein the drill is put into a V-block and rotated into a grinding position, in which a shoulder in the V-block abuts the margin of the drill. After grinding the edge so defined, the drill is once again rotated so that the other margin abuts the shoulder for grinding of the other edge. Regardless of the type of the clamping member used for the drill, it must be possible to advance the drill towards a grinding wheel to grind the drill. The most normal procedure is to make the drill chuck displaceable in a chuck housing. In drill chucks having jaws formed by V-blocks, the guidance for advancement is obtained either by wedges on a support plate for the chuck, said wedges being located in grooves in the jaws. It has also been proposed to provide the V-blocks with guide ribs received in guide grooves in the support plate. In that case, the guide grooves and the wedges are inclined towards the working surface of the grinding wheel in an extent corresponsing to half the drill point angle. A machine for such grinding with a guide groove in the support plate is illustrated in the Swedish patent 334 308. Other exainples of prior art may be obtained by the US patents 970 351 and 1 230 111 and the German publication 2 252 549.

Drills, lathe-tools and thread taps form together one of the largest expenses of mechanical work shops since zhey are normally sharpened by hand, for what reason the sizes of clearance and rake angles established by research and standarcization are seldom obtained. Thus, it would be desirable to provide a machine suitable for grinding such tools and being so non-expensive that every mechanical workshop possessing a lathe and a boring machine may be assumed to be a buyer of the machine.

BRIEF DISCLOSURE OF THE INVENTION Thus, the object of the invention is to develope the machine according to the preamble of claim 1 so as to fulfil the desire indicated hereinabove. This object is obtained by the features defined in the characterizing portion of claim 1.

BRIEF DISCLOSURE OF THE DRAWINGS An embodiment of the invention is described hereinbelow with reference to the appended drawings, in which fig 1 illustrate a front view of the machine, fig 2 a plan view of fig 1, fig 3 a view from the left of fig 1, fig 4 a view of a drill tip, fig 5 a plan view of a tool holder, fig 6 a view from the right of fig 5, fig 7 a side view of a thread tap holder clamped on the support plate, fig 8 a view from the right of fig 7, fig 9 a section along the line X-X in fig 8 and fig 10 a plan view of fig 7 .

DETAILED DISCLOSURE OF A PREFERRED EMBODIMENT On a base plate 1, a bench grinder 2 is attached and provided with a grinding wheel 3 which in a known manner is attached to the motor shaft 4.

On one side of the bench grinder, a drill holder stand 5 is located, said stand consisting of a guide plate 6 with a frame 7 carrying a support plate 8. This plate is designed with a guide groove 9 for guide rails 11 and 12 secured on a drill holder 10. By means of a feed screw 13 actuating a feed rail 14, the chuck 10 is displaceable towards the grinding wheel so that when the support plate is pivoted upwardly about a lower shaft 15, which is generally parallell to the axis of rotation of the grinding wheel, on the guide plate 6 the drill is moved adjacent the annular working surface 3 of the grinding wheel and receives the planar relief surface e₁ (fig 4), whereafter the support plate in a known manner is lowered about a shaft 150 generally perpendicular to the axis of rotation of the support plate into a greater inclination relative to the horizontal plane so that the clearance surface t₁ is formed when the support plate is pivoted upwardly once again. Thereafter, the drill holder is lifted out of its engagement: with the guide groove 9 and turned half a revolution so that the other guide rail 12 is introduced into the guide groove and the other edge gets into position for grinding. When, the support plate is pivoted upwardly along the grinding wheel, the other clearance surface t₂ is formed, whereafter the support plate is lifted to the upper position and once again moved along the grinding wheel so as to form the relief surface e₂.

When the drill is still clamped in the chuck, it is lifted, if required, to a correction stand 17, wherein the drill is correction ground. This correction grinding does not form part of the present invention.

For grinding lathe tools and thread taps, it is according to the present invention preferable that the support plate 8 may be adjusted also entirely horizontally, which occurs by means of a clearance link 20 (fig 3) on the lower side of the support plate. The link is rotatable on a pin 21 and held in engagement with a stationary clearance disc 23 on the frame by means of a spring 22, so that a stop pin 24 secured at the lower end of the clearance link is received in a step 25 in the clearance disc. The clearance link 20 may with a finger be moved out of the step 25 so that the support plate is lowered to a lower step 26 for the clearance surfaces e₁ and e₂ while the surfaces t₁ and t₂ are obtained if the pin 24 is released in the slot 27.

The holder for grinding lathe tools or other similar tools having edges according to figs 5 and 6 consists of a planar plate 29, which on its lower side is provided with a guide rail 30, which. fits into the oblique guide grove 9 in the upper side of the support plate 8. The tool holder plate 29 is provided with walls 3 1 , 32 and 33 serving as abutments for the tools to be ground. The walls 31 and 32 are related to grinding of straight roughing tools according to SMS 2760 and the wall 33 is used for cutting-off tools and are located in different angles corresponding to the setting angles and clearing angles of the tools. For grinding, the support plate 8 is first adjusted for a clearance angle of 7 , whereafter a tool 34 is put against a wall 31 and clamped against the same, whereupon the support plate 8 is pivoted upwardly so that the tool is ground. By the inclination of the support plate relative to the horisontal, the tool gets a clearance angle of 7 during the grinding. If the tool is ground is this manner previously and only requires a sharpening , this is normally obtained by advancing the tool by hand. When a setting angle c is ready, the tool is moved over to the wall 32 and during pivotal movement upwardly of the support plate, the clearing angle d is formed as setting angle.

The wall 33 is at right angles to the side plane of the grinding wheel and is intended for grinding of cutting-off tools, which during grinding are held against the wall. Due to the wedge shape of the cutting-off tools, at least one side of the wall 33 is correspondingly shaped, whereby the cutting-off tool will be at right angles to the plate 29 and the edge of the tool will be horizontal so that also the clearance surface originates from a correct edge.

At its edge located most close to the grinding wheel, the plate 29 is bent downwardly in an angle e corresponding to the rake angle for the tool. On the forward edge of the plate 29, a guide edge 35 is bent upwardly and forms a guide for the cutting tool to be ground with rake angle. The edge 35 does not, however, extend all the way to the right hand edge of the plate (fig 5) but terminates at a suitable distance therefrom so that the grinding wheel will have space to grind as much as needed for the rake angle.

Normal rake angles are 7 or 15 , for what reason the angle in this case preferably is made to be 15 which fits for the most materials. If the support plate 8 is horizontal, the rake angle will be 15 , but if the plate is adjusted for a clearance angle of 7 , the rake angle will be only 5° which is suitable for such materials as normal carbon steels, cast iron or bronze. On grinding of the rake angle, the tool is laid down into the e-channel with the tip turned towards the grinding wheel. On pivotal .movement upwardly of the support plate 8, the grinding wheel will cut a vertical plane 36 on the side of the tool facing towards the grinding wheel. Thus, said plane will be in an angle of 15 or 8 from the edge. Greater rake angles may be obtained by increasing the angle e.

On the right hand side of the plate 29, it is on its lower side provided with an attachment 37 for a diamond with a shaft 38, which is introduced into the attachment and clamped by means of a screw 39. The attachment is secured onto the plate 29 in such a position, that the diamond will be directed somewhat obliquely so as to slope at an angle of 15-30 relative to the direction of rotation of the plate. When the diamond has been clamped, the plate 29 is moved towards the grinding wheel so far that it almost contacts the grinding wheel, whereafter the feed screw 13 is rotated and moves the tool holder 29 until the diamond cuts, whereupon the diamond is moved stepwise in a suitable manner for the abrasion until the wheel is clean.

Thread taps are normally delivered with a rake angle of 7º. This causes defective threads in easy to work material such as drawn brass and aluminium, which normally requires a rake angle of 15º, and copper, silumin and magnesium, which require a rake angle of up to 35º. Since the taps are abraded mostly at the leading edges of the lands, it is more rapid and reliable to sharpen at that location instead of on the back side of the clearance bevel. The thread tap holder illustrated in figs 7-10 is adjustable for a rake angle of 0, 7, 15 and 35º. The holder is intended to operate with the support plate 8 adjusted horizontally and has a feed slide 40, which on the lower side is provided with a guide rail 41 (fig 10) which is attached to the slide and may be received in the same guide groove 9 used both for the drill holder 10 and the tool holder 29. The slide 40 is in its rear part designed with an oblique edge, which is perpendicular to the guide groove and forms an abutment surface for the cuide rail 14 of the feed screw. On top of the feed slide 40, an adjustment slide 42 is located and provided with two slots 43 for pins 44 in the feed slide so that the holder may be displaced parallell to the grinding path 3 of the grinding wheel but maintained in a fixed position by tightening a nut

45 for each pin 44. The adjustment slide 42 carrys two brackets 46, which in turn carry a pair of paraliell outer tubes 47, which each receives an inner tube 48 which is easily siidable in the outer tube. The lower ends of the inner tubes are held together by a clamp 49 which is tightened about one of the tubes with the screw 50 and the clamp itself is screwed or otherwise secured to a lower wall 51. The upper ends of the inner tubes are. rigidly connected to an upper wall 52 so that they form a slide displaceable in the outer tubes 47. In that end of the upper wall which is located close to the grinding wheel, a center pin 53 is attached for guiding the thread taps 59 to be ground. An opposite center pin 54 is screwed onto an index plate 55 rotatable on the lower wall 51. The hub 56 of the index plate passes through the lower wall and is retained by a groove ring 57. The pin 54 is completely threaded and may be received in a corresponding inner thread in the hub. By means of a head 58 of the pin, it may be rotated towards and away from the upper pin for clamping or releasing the thread tap. The index plate 55 is maintained in position relative to the carrier 60 by a latch 61, which is received in one of four grooves 65 on the index plate under the influence of the spring 63. The upper end 64 thereof is bent so that it is received in a step 62 on the latch and prevents the same from being lifted upwardly from the groove into which it has been introduced. The latch 61 is displaceable on a screw 67, which passes through an oblong slit 66 in the latch, whereby its displacement towards or away from the slit is restricted.

The grooves 65 in the index plate are radial and start with zero position corresponding to a rake angle of 0º on the thread tap and starting therefrom, the grooves are located in and 35º, whicch is indicated with corresoonding numerals o: the lower wail 51 About its circumference, the index plate is shaped with four index recesses 70 corresponding to the number of lands on the thread tap. The index plate is held stationary relative to the lower wall 51 by an index latch 71, which is rotatable on a pin 72 on the lower wall 51 and maintained in a locking position by a spring 73. The index plate may be rotated in counter clock wise direction to change land for grinding in the thread tap and thus, the index latch prevents clockwise rotation of the thread tap due to the grinding pressure. The thread tap to be ground is provided with a carrier 60, which is clamped about the shaft 68 of the tap by means of a screw 69. The thread tap is applied against the upper center pin and the lower wall is displaced upwardly until the lower pin engages the thread tap so that the wall may be clamped by means of the screw 50. By rotation of the lower pin 54 the thread tap is clamped against the upper pin 53. The latch or lock 61 is thereafter released from the spring 63 and pressed downwardly towards the index plate 55 so that the lock 61 is received in the zero groove 65 in the index plate, whereafter the carrier is loosened by loosening the screw 74 and the thread tap can be rotated. The tap is adjusted so that the leading edge of a land will be located in the side plane of the grinding wheel, such a position corresponding to a rake angle of 0º. The upper part of the upper pin 53 is designed with a diametrical step 75 which is parallell to the grinding path. By displacement of the thread tap holder by means of the feed screw, the holder is moved so that the step 75 will lie in the plane of the grinding wheel and the surface may be adjasted so that the tips of the teeth in the land only touches the wheel, while the leading edges of the teeth slope towards the same in an extent equal to the set rake angle.

If the grinding wheel is actuated, the thread tap holder with the tube slide may be moved, whereby the grinding wheel cuts on the forward side of the land. On adjustment of a rake angle larger than 5º, the land has , however, been removed from the grinding path, for what reason the entire holder must be moved towards the grinding wheel until the wheel starts to cut. This is carried out by means of the feed screw 13. To prevent that also the feed slide 40 is lifted when the tube slide is lifted for grinding, the feed slide is held against the support plate 8 and the lower portion of the adjustment slide locked against the frame. When a land has been ground and the slide returned to its lower position, the tap may be rotated to the next position on the index plate so that the next land may be ground. This procedure is repeated until all lands have been sufficiently ground. When the tube slide has been returned to its starting position, the grinding wheel is stopped and the thread tap released by unscrewing the lower pin a few revolutions. When the carrier has been moved over to the next thread tap to be ground, it can be introduced into the holder for sharpening in the above described manner. On one of the inner tubes 48, preferably the left, in fig 8 a stop member 78 may be displaced and secured by a screw 79, whereby the stroke of the tube slide is adjustable.

Claims

Claim Adjustable grinding machine for drills, lathe tools, thread taps or similar machining tools, wherein the surfaces about the cutting edges form standardized angles relative to the longitudinal extent of the tool or the tool for the rest is of a standardized design, saich machine being provided with a support plate (3), which is pivotable in a plane parallel to the plane of a grinding wheel (3), preferably a grinding saucer, and which is adjustable into varying inclination relative to a plane perpendicular to the plane of pivoting and which furhter has a guide groove (9), in which exchangeable slides for holding the tools are guided during advance by means of a feed screw (13), a drill being, on grinding of drills, clamped in a slide (10) in such an orientation that the edge of the drill facing the grinding wheel (3) extends parallel to the plane of the grinding wheel, c h a r a c t e r i z e d in that the support plate (8) is adjustable between at least three predetermined fixed inclinations, a first inclination (25) corresponding to zero position with the support plate perpendicular to the plane of the grinding wheel, a second inclination (26) corresponding to the inclination of the relief surface of a drill and the corresponding inclination of a lathe tool having such an inclination which is small, and the third inclination (27) corresponding to the inclination of the clearance surface of a drill, the slide (29) for grinding lathe tools comprising a plurality of guide edges for the lathe tool corresponding to standardized setting and clearing angles for the lathe tool, and the slide (40) for grinding thread taps (59) comprising a holder (52), wherein the thread tap is clamped and may be moved perpendicularly to the plane of the support plate and held with the leading face of a land so that it is ground to the desired back rake angle, said holder being rotatable about the axis of the thread tap into different defined angle positions corresponding to the location of the lands on the thread tap.

2. A grinding machine according to claim 1, c h a r a c t e r i z e d in that the lathe tool slide (29) at its end facing the grinding wheel (3) is bent downwardly to an angle corresponding to the normal rake angle of the tool (34) and that the outermost edge of the slide is bent upwardly into a guide edge (35) for holding the tool (34) by hand during grinding.

3. A grinding machine according to claim 2, c h a r a c t e r i z e d in that the lathe tool (34) during the grinding movement of the support plate (3) obtains a greater rake angle with the support plate adjusted to said first inclination and a smaller rake angle with the support plate adjusted to said second inclination.

4. A grinding machine according to claim 1, c h a r a c t e r i z e d in that the slide (40) for the thread tap holder supports an adjustment. slide (42) having a support (46), in which two parallel outer tubes (47) form guide means for inner tubes (48), which at their outer ends are held together by walls (51, 52) to form a support slide, which is displaceable in the outer tubes, said walls carrying pins (53, 54) for holding a thread tap, whereby the thread tap upon displacement of the support slide and movement past the grinding wheel is ground on the forward side of one of its lands into a rake angle which is adjustable by means of an index plate (55).

5. A grinding machine according to claim 4, c h a r a c t e rized in that the lower wall (51) supports the index plate (55) which is provided with a hub (56) passing through the wall and being retained by a groove ring (57), said index plate being provded with recesses (70) distributed on the circumference of the plate for a rotatable latch (71) on the wall, said recesses being equal in number to the number of lands on the thread tap.

6. A grinding machine according to claim 4 and 5, c h a r a c t e r i z e d in that a carrier (60) which may be cla.mped on the thread tap (59) to hold the same during grinding, is provided with a lock member (61), which, preferably by means of a spring, is pressed downwardly into a rake angle groove (65) in the index plate for the rake angle to be ground onto the tap, whereby the carrier, after adjustment of the same in the groove, is clamped about the thread tap, e.g. by means of a screw, and thereby retained in the desired rake angle when the support slide is lifted for grinding.

7. A grinding machine according to claim 5, c h a r a c t e r i z e d in that the pin (58) located in the index plate (55) is threaded in the hub (56) so that it can be screwed out to release the thread tap and screwed in to clamp the same.

8. A grinding machine according to claim 2, c h a r a c t e r i z e d in that the lathe tool holder (29) supports an attachment (37) for a diamond holder shaft (38), which when needed may be clamped in the attachment and displaced toward the grinding wheel by means of the feed screw (13) into a desired position for turning the grinding wheel by means of the diamond.