Apparatus for grinding drills

Claim 2

Apparatus for grinding drills having at least two main cutting edges and having a clearance surface for each main cutting edge, comprising a rotatable grinding wheel provided with at most two grinding surfaces and at least one set of guiding means for guiding a drill head in relation to the wheel, the guiding means having means for providing an essentially constant operative angle between the geometrical longitudinal axis of the drill and the rotary plane of the wheel and admitting a rotation of the drill about said axis, at least one first stop means for engaging the drill and thereby preventing rotation of the drill about its axis in one direction beyond a first limiting position and at least one second stop means for engaging the drill and thereby preventing rotation of the drill about its axis in a direction opposite to said one direction beyond a second limiting position, said first and second stop means being so arranged with respect to one another and to a drill in said guiding means as to be operable to limit said rotation of said drill to a predetermined angular extent between said first and second limiting positions such that when said drill is rotated between said limiting positions and through said predetermined angular extent while a clearance surface thereof is in contact with an associated rotating grinding surface a predetermined clearance angle and a predetermined transversal cutting edge angle are both obtained.

Claim 3

Apparatus according to claim 1, wherein each set of guiding means consists of a cylindrical guiding passage provided in a guiding element and said first and second stop means are provided by at least one guide lug having a pair of oppositely disposed abutment margins and being associated with the guiding passage for fitting into a flute of a drill, rotation of the drill about its axis in said one direction beyond said first limiting position being prevented by engagement of said drill with one of said abutment margins and rotation of the drill about its axis in said opposite direction beyond said second limiting position being prevented by engagement of said drill with the other abutment margin.

Claim 4

Apparatus according to claim 2, wherein there is provided a number of guiding passages and guide lugs associated therewith, which guiding passages have different diameters for guiding drills of different diameters.

Claim 5

Apparatus according to claim 3, further provided with means whereby the wheel, by increasing resistance, resiliently recoils to the pressure exerted by at least one clearance surface urged against its corresponding grinding surface, and means for so intercepting the advance of the drill as to determine a substantially steady operative distance between the tip of the drill and the guide lugs and a stable resilient counterforce of the wheel.

Claim 6

Apparatus according to claim 4, wherein the wheel is provided with one grinding surface and the means intercepting the advance of the drill consists of an abutment for receiving the clearance surface not engaging the grinding surface.

Claim 7

Apparatus according to claim 5, wherein the abutments are united in one abutment element having a stop face advancing helically in the direction of the rotational axis of the wheel at a common distance from said axis, and wherein the guiding passages are so distributed according to their diameters over said stop face that a drill, inserted into its appropriate guiding passage and urged onto the stop face, will cause the wheel to recoil a distance which is so increased by increased drill diAmeter that the resilient counterforce of the wheel will produce approximately the same grinding pressure for any drill that is receivable.

Claim 8

Apparatus according to claim 6, further provided with means whereby the distance between the stop face and the guide lugs can be varied.

Claim 9

Apparatus according to claim 1, wherein the wheel is provided with two conical grinding surfaces meeting along a circular border at an angle appropriate to the point angle of the drill.

Claim 10

Apparatus according to claim 8, wherein there is a slight clearance between the grinding surfaces along the meeting circular border of these surfaces.

Claim 11

Apparatus according to claim 8, wherein each set of guiding means consists of a cylindrical guiding passage provided in a guiding element and said first and second stop means are provided by at least one guide lug having a pair of oppositely disposed abutment margins and being associated with the guiding passage for fitting into the flute of a drill, rotation of the drill about its axis in said one direction beyond said first limiting position being prevented by engagement of said drill with one of said abutment margins and rotation of the drill about its axis in said opposite direction beyond said second limiting position being prevented by engagement of said drill with the other abutment margin.

Claim 12

Apparatus according to claim 10, wherein is provided a number of guiding passages and guide lugs associated therewith, which guiding passages have different diameters for guiding drills of different diameters.

Claim 13

Apparatus according to claim 11, wherein there is a slight clearance between the grinding surfaces along the meeting circular border of these surfaces.

Claim 14

Apparatus according to claim 12, further provided with means whereby the distance between the grinding surfaces and the guide lugs is adjustable.

Claim 15

Apparatus for grinding spiral drill bits having at least one main cutting surface and having a clearance surface and a flute for each main cutting surface, comprising a rotatable grinding wheel having a grinding surface and means for connecting the wheel to a driving device and means for guiding a drill bit in relation to the grinding surface, the guiding means having means providing a constant angle between the geometrical longitudinal axis of the drill and the grinding surface during the grinding operation, at least one first stop means for engaging the drill and thereby preventing rotation of the drill about its axis in one direction beyond a first limiting position and at least one second stop means for engaging the drill and thereby preventing rotation of the drill about its axis in a direction opposite to said one direction beyond a second limiting position, said first and second stop means being so arranged with respect to one another and to a drill in said guiding means as to be operable to limit the rotational movement of the drill bit to a predetermined angular extent between said first and second limiting position such that when said drill is rotated between said limiting positions and through said predetermined angular extent while a clearance surface thereof is in contact with an associated rotating grinding surface a predetermined clearance angle and a predetermined transversal cutting edge angle are both obtained.

Claim 16

Apparatus for grinding spiral drill bits having at least one main cutting surface and having a clearance surface and a flute for each main cutting surface, comprising a rotatable grinding wheel having a grinding surface and means for connecting the wheel to a driving device and means for guiding a drill bit in relation to the grinding surface, the guiding means having means providing a constant angle between the geometrical longitudinal axis of the drill and the grinding surface during the grinding operation, at least one first stop means for engaging the drill and thereby preventing rotation of the drill about its axis in one direction beyond a first limiting position and at least one second stop means for engaging the drill and thereby preventing rotation of the drill about its axis in a direction opposite to said one direction beyond a second limiting position, said first and second stop means being so arranged with respect to one another and to a drill in said guiding means as to be operable to limit the rotational movement of the drill bit to a predetermined angular extent between said first and second limiting position such that when said drill is rotated between said limiting positions and through said predetermined angular extent while a clearance surface thereof is in contact with an associated rotating grinding surface a predetermined clearance angle and a predetermined transversal cutting edge angle are both obtained.

Claim 17

Apparatus for grinding spiral drill bits having at least one main cutting surface, a transversal cutting surface intersecting the main cutting surface and one clearance surface and a flute for each main cutting surface, comprising a rotatable wheel having a bowl-shaped conical grinding surface and having means for connecting the wheel to a driving device, a guiding element fixed in relation to the rotational axis of the wheel, a number of cylindrical guiding passages having different diameters one of which is largest and one of which is smallest provided in the guiding element at equal distances from the rotational axis of the wheel and extending in parallel thereto, for guiding drill bits of different diameters in relation to the grinding surface, guiding pins in the guiding passages adapted to engage each with one of the flutes of the drill bits in order to limit the rotational movement of the drill bits between two limiting positions corresponding to the points of engagement of said flutes and said pins, said pins being so arranged with respect to one another and to a drill bit in said guiding passage as to be operable to limit said rotation to a predetermined angular extent between said limiting positions such that when said drill is rotated between said limiting positions and through said predetermined angular extent while a clearance surface thereof is in contact with an associated rotating grinding surface a predetermined clearance angle and a predetermined transversal cutting edge angle or both obtained and an abutment united with the guiding element for determining the position of the drill bits in relation to the guiding pins.

Claim 18

Apparatus for grinding spiral drill bits having at least one main cutting surface, a transversal cutting surface intersecting the main cutting surface and one clearance surface and a flute for each main cutting surface, comprising a rotatable wheel having a bowl-shaped conical grinding surface and having means for connecting the wheel to a driving device, a guiding element fixed in relation to the rotational axis of the wheel, a number of cylindrical guiding passages having different diameters one of which is largest and one of which is smallest provided in the guiding element at equal distances from the rotational axis of the wheel and extending in parallel thereto, for guiding drill bits of different diameters in relation to the grinding surface, guiding pins in the guiding passages adapted to engage each with one of the flutes of the drill bits in order to limit the rotational movement of the drill bits between two limiting positions corresponding to the points of engagement of said flutes and said pins, said pins being so arranged with respect to one another and to a drill bit in said guiding passage as to be operable to limit said rotation to a predetermined angular extent between said limiting positions such that when said drill is rotated between said limiting positions and through said predetermined angular extent while a clearance surface thereof is in contact with an associated rotating grinding surface a predetermined clearance angle and a predetermined transversal cutting edge angle or both obtained and an abutment united with the guiding element for determining the position of the drill bits in relation to the guiding pins.

Claim 19

Apparatus as claimed in claim 15, wherein the wheel is mounted for resilience in an axial direction under the influence of the pressure from a drill bit pressed against the grinding surface, the pressure of the drill bit against the grinding surface being limited by the abutment for providing a constant grinding pressure.

Claim 20

Apparatus as claimed in claim 15, wherein the guiding passages are of essentially the same diameter as the drill bit.

Claim 21

Apparatus as claimed in claim 15, wherein the guiding pins are disposed diametrically opposite each other in the guiding passage and extend inwards approximately one fourth of a guiding passage diameter towards the center of the guiding passage and being each provided with two straight abutments margins extending along two different diameters of the guiding passage forming an angle of 60* with each other.

Claim 22

Apparatus as claimed in claim 15, wherein the distance between the abutment and the guiding pins in the direction of the geometrical axis of the wheel is adjustable in order to provide different clearance angles for the clearance surfaces of the drill bits.

Claim 23

Apparatus as claimed in claim 15, wherein the abutment is common to all guiding passages and extends along a helical turn, the center axis of which coincides with the rotational axis of the wheel and the radius of which is slightly shorter than the radius of the circle cutting the center axes of all guiding passages.

Claim 24

Apparatus as claimed in claim 15, wherein the largest guiding passage is directed towards that point of the abutment which is nearest to the grinding surface, while the smallest guiding passage is directed towards the point that is most remote therefrom, while the other guiding passages are distributed therebetween according to their diameters.

Claim 25

Apparatus for grinding drills having at least one main cutting surface and one clearance surface and a flute for each cutting surface comprising a rotatable wheel having a conical grinding surface, means connected to the wheel for driving the wheel, a guiding element, at least one cylindrical guiding passage provided in the guiding element for guiding drill bits in relation to the grinding surface, at least one first stop means in the guiding passage for engaging a flute of a drill within the guiding passage and thereby preventing rotation of the drill about its axis in one direction beyond a first limiting position and at least one second stop means in the guiding passage for engaging a flute of the drill and thereby preventing rotation of the drill about its axis in a direction opposite to said one direction beyond a second limiting position, said first and second stop means being so arranged with respect to one another and to a drill within the guiding passage as to be operable to limit the rotational movement of the drill to a predetermined angular extent between said first and second limiting positions such that when said drill is rotated between said limiting positions and through said predetermined angular extent while a clearance surface thereof is in contact witH an associated rotating grinding surface a predetermined clearance angle and a predetermined transversal cutting edge angle are both obtained.

Claim 26

Apparatus for grinding drills having at least one main cutting surface and one clearance surface and a flute for each cutting surface comprising a rotatable wheel having a conical grinding surface, means connected to the wheel for driving the wheel, a guiding element, at least one cylindrical guiding passage provided in the guiding element for guiding drill bits in relation to the grinding surface, at least one first stop means in the guiding passage for engaging a flute of a drill within the guiding passage and thereby preventing rotation of the drill about its axis in one direction beyond a first limiting position and at least one second stop means in the guiding passage for engaging a flute of the drill and thereby preventing rotation of the drill about its axis in a direction opposite to said one direction beyond a second limiting position, said first and second stop means being so arranged with respect to one another and to a drill within the guiding passage as to be operable to limit the rotational movement of the drill to a predetermined angular extent between said first and second limiting positions such that when said drill is rotated between said limiting positions and through said predetermined angular extent while a clearance surface thereof is in contact witH an associated rotating grinding surface a predetermined clearance angle and a predetermined transversal cutting edge angle are both obtained.

Claim 27

Apparatus as set forth in claim 22, wherein a number of cylindrical guiding passages are provided in the guiding element at equal distances from the rotational axis of the wheel and extending parallel thereto which guiding passages have different diameters for guiding drill bits of different diameters in relation to the grinding surface.

Claim 28

Apparatus as set forth in claim 22, wherein the means of the guiding passage is a pin in the guiding passage the size of which corresponds to the intended angle between the main cutting surface and the transversal cutting surface of the drill bit.

Claim 29

Apparatus as set forth in claim 22 and further including an abutment united with the guiding element for determining the postion of the drill bit in relation to the means in the guiding passage and consequently the position of the angular area in relation to the grinding surface so that the clearance surface of the drill bit will obtain the intended clearance angle when being pressed against the rotating grinding surface while rotating the drill bit within the angular area corresponding to the clearance surface.

Claim 30

Apparatus for grinding spiral drills having two main cutting edges and having a clearance surface and a flute for each main cutting edge, comprising a rotatable grinding wheel of which the grinding surface consists of an internal and an external conical part, means for guiding the clearance surfaces of the main cutting edges relatively to the grinding surface of the wehel, said means having means for guiding the drill so that the axis of the drill is parallel to and located at a distance from the axis of the grinding wheel which is equal to the radius of the circular intersection between the internal and the external conical part of the grinding surface, at least one first stop means for engaging the drill and thereby preventing rotation of the drill about its axis in one direction beyond a first limiting position and at least one second stop means for engaging the drill and thereby preventing rotation of the drill about its axis in a direction opposite to said one direction beyond a second limiting position, said first and second stop means being so arranged with respect to one another and to a drill in said guiding means as to be operable to limit rotary movement of the drill about its axis to a predetermined angular extent between said first and second limiting positions such that when said drill is rotated between said limiting positions and through said predetermined angular extent while a clearance surface thereof is in contact with an associated rotating grinding surface a predetermined clearance angle and a predetermined transversal cutting edge angle are both obtained.

Claim 31

Apparatus for grinding spiral drills having two main cutting edges and having a clearance surface and a flute for each main cutting edge, comprising a rotatable grinding wheel of which the grinding surface consists of an internal and an external conical part, means for guiding the clearance surfaces of the main cutting edges relatively to the grinding surface of the wehel, said means having means for guiding the drill so that the axis of the drill is parallel to and located at a distance from the axis of the grinding wheel which is equal to the radius of the circular intersection between the internal and the external conical part of the grinding surface, at least one first stop means for engaging the drill and thereby preventing rotation of the drill about its axis in one direction beyond a first limiting position and at least one second stop means for engaging the drill and thereby preventing rotation of the drill about its axis in a direction opposite to said one direction beyond a second limiting position, said first and second stop means being so arranged with respect to one another and to a drill in said guiding means as to be operable to limit rotary movement of the drill about its axis to a predetermined angular extent between said first and second limiting positions such that when said drill is rotated between said limiting positions and through said predetermined angular extent while a clearance surface thereof is in contact with an associated rotating grinding surface a predetermined clearance angle and a predetermined transversal cutting edge angle are both obtained.

Claim 32

Apparatus as claimed in claim 26, wherein the grinding wheel is axially movable against a resilient force and wherein the means limiting the rotary movement of the drill about its axis join the axisl movement of the grinding wheel.

Claim 33

Apparatus as claimed in claim 26, wherein the distance in the direction of the axis of the grinding wheel between the means limiting the rotary movement of the drill and the grinding wheel is adjustable.

Claim 34

Apparatus for grinding drills having at least one main cutting edge and having a flute and a clearance surface for each main cutting edge, comprising a rotatable grinding wheel having a grinding surface, means for guiding the clearance surfaces of the main cutting edges relative to the grinding surface of the wheel, said means having means for guiding the drill so that the axis of the grinding wheel and the axis of the drill are located in two mutually fixed straight lines during the grinding operation at least one first stop means for engaging the drill and thereby preventing rotation of the drill about its axis in one direction beyond a first limiting position and at least one second stop means for engaging the drill aNd thereby preventing rotating of the drill about its axis in a direction opposite to said one direction beyond a second limiting position, said first and second stop means being so arranged with respect to one another and to a drill in said guiding means as to be operable to limit rotary movement of the drill about its axis to a predetermined angular extent between said first and second limiting positions such that when said drill is rotated between said limiting positions and through said predetermined angular extent while a clearance surface thereof is in contact with an associated rotating grinding surface a predetermined clearance angle and a predetermined transversal cutting edge angle are both obtained.

Claim 35

Apparatus for grinding drills having at least one main cutting edge and having a flute and a clearance surface for each main cutting edge, comprising a rotatable grinding wheel having a grinding surface, means for guiding the clearance surfaces of the main cutting edges relative to the grinding surface of the wheel, said means having means for guiding the drill so that the axis of the grinding wheel and the axis of the drill are located in two mutually fixed straight lines during the grinding operation at least one first stop means for engaging the drill and thereby preventing rotation of the drill about its axis in one direction beyond a first limiting position and at least one second stop means for engaging the drill aNd thereby preventing rotating of the drill about its axis in a direction opposite to said one direction beyond a second limiting position, said first and second stop means being so arranged with respect to one another and to a drill in said guiding means as to be operable to limit rotary movement of the drill about its axis to a predetermined angular extent between said first and second limiting positions such that when said drill is rotated between said limiting positions and through said predetermined angular extent while a clearance surface thereof is in contact with an associated rotating grinding surface a predetermined clearance angle and a predetermined transversal cutting edge angle are both obtained.

Claim 36

Apparatus as claimed in claim 29, wherein the grinding wheel is mounted for resilience under the influence of the pressure from a drill pressed against the grinding surface, and wherein the means limiting the rotary movement of the drill about its axis join the resilient movement of the wheel.

Claim 37

Apparatus as claimed in claim 29, wherein the axial travel of the drill against the resiliently movable grinding wheel is limited by an abutment engaging the clearance surface of the drill bit not engaging with the grinding surface of the wheel.

Claim 38

Apparatus as claimed in claim 30, wherin the distance between the means limiting the rotary movement of the drill about its axis and the grinding surface of the wheel is adjustable.