Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B3/00—Sharpening cutting edges, e.g. of tools; Accessories therefor, e.g. for holding the tools

Definitions

• 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.
• 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.
• 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.
• 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
• fig 10 a plan view of fig 7 .
• a bench grinder 2 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.
• a drill holder stand 5 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.
• 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 e 1 (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 t 1 is formed when the support plate is pivoted upwardly once again.
• 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.
• the support plate is pivoted upwardly along the grinding wheel, the other clearance surface t 2 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 e 2 .
• 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 e 1 and e 2 while the surfaces t 1 and t 2 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.
• 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.
• 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.
• 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.
• the plate 29 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.
• a guide edge 35 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.
• the tool 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.
• the plate 29 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.
• the plate 29 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.
• 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
• 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.
• 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.
• 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.
• the holder 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.
• the thread tap holder with the tube slide may be moved, whereby the grinding wheel cuts on the forward side of the land.
• 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.
• 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.
• 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.
• a stop member 78 may be displaced and secured by a screw 79, whereby the stroke of the tube slide is adjustable.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20342976

Family Applications (1)

Country Status (3)

Families Citing this family (6)

Family Cites Families (8)

• 1981
  • 1981-01-26 SE SE8100442A patent/SE432216B/sv not_active IP Right Cessation
• 1982
  • 1982-01-26 WO PCT/SE1982/000020 patent/WO1982002507A1/en unknown
  • 1982-01-26 EP EP19820900397 patent/EP0072811A1/de not_active Withdrawn

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events