FIELD OF THE INVENTION

The present invention relates to a tool holder for use in metal cutting processes in general, and for parting and grooving operations in particular.

BACKGROUND OF THE INVENTION

Within the field of parting and grooving of a rotating metal workpiece, a cutting insert may be secured in a blade shaped insert holder, and the insert holder in turn releasably retained in a tool holder. The tool holder typically comprises a main block with a longitudinal channel or groove, and a means of clamping the insert holder within the longitudinal channel or groove.

US 5,031,492 and US 5,079,979 each disclose a tool holder, where an insert holder is clamped within a main block by means of a single clamping member. The clamping member forms an upper wall of a longitudinal groove and interfaces with an upper ridge shaped surface of the insert holder. Several clamping screws pass through holes in the clamping member and into corresponding threaded bores in the main block. A clamping operation is performed by rotating the clamping screws until each applies a sufficient clamping force between the insert holder and a lower wall of the longitudinal groove of the main block. The clamping forces are released by rotating the clamping screws in an opposite direction. They both employ at least three clamping screws thereby requiring the screwing of at least three screws. They both require approach from the top to tighten the screws, which may not always be possible.

US 3,531,842 discloses a tool holder, where a cutting insert and support blade are clamped within a main block by means of a single wedge shaped clamping member. The wedge shaped clamping member is positioned against an upper wall of a longitudinal groove of the main block and interfaces with an upper surface of the cutting insert. A means of clamping actuation is provided by a double threaded member interfacing with corresponding threaded bores in the main block and the wedge shaped clamping member. A clamping operation is performed by rotating the double threaded member, which causes the wedge shaped clamping member to move in a longitudinal direction relative to the main block, until a sufficient clamping force is applied between the cutting insert and support blade and a lower wall of the longitudinal groove of the main block. The clamping force is released by rotating the double threaded member in an opposite direction. Although the clamping operation is performed by a single means of clamping adjustment, this solution has a limited flexibility of configuration in that the cutting insert can only operate from one end of the main block. Also, clamping is provided along only a short section of the longitudinal groove, thus limiting the distance that the cutting insert and support blade can be extended beyond the main block and acceptably perform a parting and grooving operation. It is an object of the present invention to provide a tool holder for clamping an insert holder which significantly reduces or overcomes the aforementioned disadvantages.

SUMMARY OF THE INVENTION In accordance with preferred embodiments of the present invention, there is provided a tool holder comprising: a main block having a longitudinal side surface with a longitudinal groove with opposing upper and lower walls; two wedge shaped clamping members, supported by the lower wall of the longitudinal groove; and a single adjustment member operatively connected to each of the two clamping members; wherein the two clamping members are configured to clamp a blade shaped insert holder against the upper wall of the longitudinal groove.

Also in accordance with preferred embodiments of the present invention, there is a method of clamping a blade shaped insert holder in a tool holder, the tool holder comprising: a main block having a longitudinal side surface with a longitudinal groove with opposing upper and lower walls; two wedge shaped clamping members, supported by the lower wall of the longitudinal groove; and a single adjustment member operatively connected to each of the two clamping members, the method comprising the steps of: mounting the insert holder in the longitudinal groove to interface with the two clamping members; and rotating the adjustment member to cause movement of each clamping member up a respective inclined non-parallel planar ramping surface of the lower wall of the longitudinal groove, until a distance between the two clamping members and the upper wall of the longitudinal groove is decreased to a point wherein a clamping force is applied between the insert holder and the upper wall of the longitudinal groove.

Further in accordance with preferred embodiments of the present invention, there is provided a tool holder comprising: a main block having an upper wall spaced apart from a lower wall, the upper wall facing in a direction of the lower wall, the lower wall comprising first and second ramping surfaces which extend away from each other and towards the upper wall; left and right clamping members supported by the first and second ramping surfaces, respectively, the left and right clamping members having respective first and second clamping surfaces which face in a direction of the upper wall; and an adjustment member operatively connected to both clamping members; wherein: the left and right clamping members are configured to travel along the first and second ramping surfaces and thereby adjust a distance between their clamping surfaces and the upper wall, in response to operation of the adjustment member.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding, the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Fig. 1 is a perspective view of a tool holder in accordance with a first embodiment of the present invention;

Fig. 2 is a side view of the tool holder shown in Fig. 1 ;

Fig. 3 is an exploded perspective view of the tool holder shown in Fig. 1 ; Fig. 4 is an end view of the tool holder shown in Fig. 1 ;

Fig. 5 is a cross sectional view of the tool holder shown in Fig. 2 taken along the line V-V;

Fig. 6 is of a perspective view of a tool holder in accordance with a second embodiment of the present invention;

DETAILED DESCRIPTION OF THE INVENTION

Attention is drawn to Figs. 1 to 3, showing a tool holder 10 comprising a main block 12 with four longitudinal side surfaces, where a first longitudinal side surface 14 has a longitudinal groove 16 with opposing upper and lower walls 18, 20.

The main block 12 has mirror symmetry about a central plane P perpendicular to the first longitudinal side surface 14, where the upper wall 18 of the longitudinal groove 16 has a single planar surface 22 and the opposing lower wall 20 of the longitudinal groove 16 has two non-parallel planar ramping surfaces 24, 26. Each of the two non-parallel planar ramping surfaces 24, 26 of the lower wall 20 of the longitudinal groove 16 are inclined at an acute angle θ relative to the single planar surface 22 of the opposing upper wall 18, in a side view as shown in Fig. 2, where the longitudinal groove 16 has a height dimension H which increases towards the central plane P. The longitudinal groove 16 may have a dovetail shape in an end view as shown in Fig. 4, where each of the opposing upper and lower walls 18, 20 is inclined relative to a side wall 28 of the longitudinal groove 16.

A blade shaped insert holder 30 is mounted in the longitudinal groove 16 of the main block 12 and clamped against the upper wall 18 of the longitudinal groove 16 by two wedge shaped clamping members 32, 34.

The insert holder 30 has two opposing major side surfaces 36, 38 and parallel upper and lower ridge shaped surfaces 40, 42. The insert holder 30 may be rotationally symmetrical by 180° about a lateral axis Al perpendicular to the two major side surfaces 36, 38 and include two insert receiving pockets 44, 46, as shown in Fig. 3. A cutting insert 48 is secured in one or both of the insert receiving pockets 44, 46.

The two clamping members 32, 34 are comprised of a left clamping member 32 and a non-identical right clamping member 34, each having an acute wedge angle θ between a planar support surface 50, 52 and a planar clamping surface 54, 56. The left and right clamping members 32, 34 are mirror symmetrical and have adjustment surfaces 58, 60 adjacent the support and clamping surfaces 50, 52 and 54, 56.

The support surface 50 of the left clamping member 32 interfaces with a first non-parallel planar ramping surface 24 of the lower wall 20 of the longitudinal groove

16, and the support surface 52 of the right clamping member 34 interfaces with a second non-parallel planar ramping surface 26 of the lower wall 20 of the longitudinal groove

16.

The clamping surfaces 54, 56 of the left and right clamping members 32, 34 are co-planar and may be inclined relative to the side wall 28 of the longitudinal groove 16, when viewed in the direction of the central plane P, as shown in Fig. 4. The clamping surfaces 54, 56 of the left and right clamping members 32, 34 each have longitudinal edges 62, 64 of length L which are co-linear, and parallel to the upper wall 18 of the longitudinal groove 16. The longitudinal groove 16 may have a length approximately equal to 2L.

According to a first embodiment of the present invention, a clamping operation is performed by a single adjustment member 68. In accordance with the first embodiment, the adjustment member 68 is generally cylindrical shaped with a central axis A2 and left and right handed male threaded ends 70, 72. The central axis A2 of the adjustment member 68 is parallel to the clamping surfaces 54, 56 of the left and right clamping members 32, 34, and the left handed male threaded end 70 mates with a left handed female threaded bore 74 in the adjustment surface 58 of the left clamping member 32, and the right handed male threaded end 72 mates with a right handed female threaded bore 76 in the adjustment surface 60 of the right clamping member 34. As shown in Fig. 3, a central gap 78 between the first and second non-parallel planar ramping surfaces 24, 26 of the lower wall 20 of the longitudinal groove 16 provides access for a spanner (not shown) to engage with two opposing flat surfaces of a hexagonal profiled middle portion 80 of the adjustment member 68, and be rotated in a clockwise or anti-clockwise direction. References to clockwise and anti-clockwise direction in this first embodiment of the present invention are made with respect to rotation of the adjustment member 68 about the central axis A2, when viewed in the direction as shown in Fig. 5. Rotation of the adjustment member 68 in a clockwise direction causes the left and right handed male threaded ends 70, 72 to simultaneously 'unscrew' from their respective female threaded bores 74, 76 of the left and right clamping members 32, 34, resulting in an increased distance Dl between the adjustment surfaces 58, 60 of the two clamping members 32, 34.

The increased distance Dl corresponds with a decreased distance D2 between the co-planar clamping surfaces 54, 56 of the left and right clamping members 32, 34 and the upper wall 18 of the longitudinal groove 16 due to the movement of the left and right clamping members 32, 34 up the inclined first and second non-parallel ramping surfaces 24, 26, respectively. The relationship between a change in distance Dl of magnitude ΔD1 and a change in distance D2 of magnitude ΔD2 is given by the following equation; ΔD2 = ΔD1 tan θ / 2, and where ΔD2 occurs simultaneously and uniformly along the longitudinal length L of each co-planar clamping surface 54, 56 of the left and right clamping member 32, 34. The co-planar clamping surfaces 54, 56 of the left and right clamping members

32, 34 simultaneously interface with the lower ridge shaped surface 42 of the insert holder 30, and at a point of the clamping adjustment where distance D2 is sufficiently decreased a clamping force F is uniformly applied between the upper ridge shaped surface 40 of the insert holder 30 and the upper wall 18 of the longitudinal groove 16. Rotation of the adjustment member 68 in an anti-clockwise direction, causes the left and right handed male threaded ends 70, 72 to simultaneously 'screw' into their respective female threaded bores 74, 76 of the left and right clamping members 32, 34, resulting in a decreased distance Dl between the adjustment surfaces 58, 60 of the two clamping members 32, 34. The decreased distance Dl corresponds with an increased distance D2 between the co-planar clamping surfaces 54, 56 of the left and right clamping members 32, 34 and the upper wall 18 of the longitudinal groove 16, where a change in distance D2 of magnitude ΔD2 occurs simultaneously and uniformly along the longitudinal length L of each co-planar clamping surface 54, 56 of the left and right clamping member 32, 34. Thus, as can be seen from the foregoing, the main block 12 has an upper wall 18 spaced apart from a lower wall 20 and facing in a direction of the lower wall 20. The lower wall's ramping surfaces 24, 26 extend away from each other and towards the upper wall 18. The left and right clamping members 32, 34 are supported by the first and second ramping surfaces 24, 26 and have respective first and second clamping surfaces 54, 56 which face in a direction of the upper wall 18, and the adjustment member 68 is operatively connected to both clamping members 32, 34. The left and right clamping members 32, 34 are configured to travel along the first and second ramping surfaces 24, 26 and thereby adjust the distance D2 between both of the left and right clamping surfaces 54, 56 and the upper wall 18, in response to operation of the adjustment member 68.

At a point of clamping adjustment where distance D2 is sufficiently increased, the clamping force F is uniformly released from between the upper ridge shaped surface 40 of the insert holder 30 and the upper wall 18 of the longitudinal groove 16.

Two identical retaining pins 82 are removably fixed into mounting holes 84, 86 in the main block 12, where each retaining pin 82 interfaces with a retaining slot 88, 90 in each of the two clamping members 32, 34. The retaining pins 82 help ensure that each clamping member 32, 34 remains supported by its corresponding ramping surface and in close proximity with the side wall 28 of the longitudinal groove 16 during clamping adjustment and during parting and grooving operations. As an alternative to retaining pins 82 removably fixed into mounting holes 84, 86, two retaining screws may be removably fixed into threaded bores in the main block 12. In some embodiments, the adjustment member 68 may also be configured such that the left handed male threaded end 70 mates with a female threaded bore in the adjustment surface 60 of the right clamping member 34, and the right handed male threaded end 72 mates with a male threaded bore in the adjustment surface 58 of the left clamping member 32. For this alternative configuration, rotation of the adjustment member 68 in an anti-clockwise direction promotes clamping of the insert holder 30 against the upper wall 18 of the longitudinal groove 16, and rotation of the adjustment member 68 in a clockwise direction promotes release of the insert holder 30 from the upper wall 18 of the longitudinal groove 16.

An advantage of the present invention is that during parting and grooving operations, the cutting action between the operative cutting insert 48 and a rotating workpiece (not shown) attempts to force the insert holder 30 and the two clamping members 32, 34 rearwards in a longitudinal direction, resulting in the rear-most left clamping member 32 exerting an increased clamping force between the insert holder 30 and the upper wall 18 of the longitudinal groove 16. Since the main block 12 is symmetrical about the central plane P, the insert holder 30 and operative cutting insert 48 may be configured such that the left clamping member 32 or the right clamping member 34 is rear-most in the tool holder 10, where each configuration provides an equally high level of clamping performance.

Significant cutting forces are also transmitted through the operative cutting insert 48 and insert holder 30 in a downward direction through the forward-most right clamping member 34, where since the main block 12 is symmetrical about the central plane P, the insert holder 30 and operative cutting insert 48 may be configured such that the left clamping member 32 or the right clamping member 34 is forward-most in the tool holder 10. Another advantage of the present invention is that the two clamping members 32, 34 are replaceable components with relatively simple geometry, and can be economically manufactured from a hardened material to provide improved wear resistance.

Although the tool holder 10 may be typically secured in a turret head recess (not shown), with the insert holder 30 positioned above the two clamping members 32, 34 and the operative cutting insert 48 secured in a first insert receiving pocket 44 adjacent the upper wall 18 of the longitudinal groove 16, it should be appreciated that the tool holder 10 may also be configured such that the insert holder 30 is positioned below the two clamping members 32, 34 and the operative cutting insert 48 secured in a second insert receiving pocket 46 adjacent the lower wall 20 of the longitudinal groove 16. This flexibility of configuration has an advantage in situations where greater access is required to turret head securing features (not shown) from below the first longitudinal side surface 14 of the main block 12, where the upper wall 18 of the longitudinal groove 16 can be described as a lower wall, and the lower wall 20 of the longitudinal groove 16 can be described as an upper wall.

Reference is now made to Fig. 6. In accordance with a second embodiment of the present invention, an alternative single adjustment member 94 is employed. This adjustment member 94 is frustoconical shaped and threadably engages the first longitudinal side surface 14 of the main block 12, between the two clamping members 32, 34. The frustoconical shaped adjustment member 94 has a hexagonal profiled recess 96 in an outwardly facing major diameter base surface 98 which provides means for an Allen key (not shown) to rotate the frustoconical shaped adjustment member 94 in a clockwise or anti-clockwise direction, when viewed in the direction of the first longitudinal side surface 14. A peripheral contact surface 100 adjacent the outwardly facing major diameter base surface 98 makes simultaneous contact with each of the two clamping members 32, 34.

Rotation of the frustoconical shaped adjustment member 94 in a clockwise direction causes the outwardly facing major diameter base surface 98 to move towards the first longitudinal side surface 14 and an increased diameter portion of the peripheral contact surface 100 to make contact with the two clamping members 32, 34, resulting in an increased distance Dl between the adjustment surfaces 58, 60 of the two clamping members 32, 34.

The increased distance Dl corresponds with a decreased distance D2 between the co-planar clamping surfaces 54, 56 of the left and right clamping members 32, 34 and the upper wall 18 of the longitudinal groove 16. At a point of the clamping adjustment where D2 is sufficiently decreased, a clamping force F is uniformly applied between the upper ridge shaped surface 40 of the insert holder 30 and the upper wall 18 of the longitudinal groove 16.

An advantage of the second embodiment of the present invention is that rotation of the frustoconical shaped adjustment member 94 and thus clamping of the insert holder 30, can be performed with limited access to the first longitudinal side surface 14.

Although the present invention has been described to a certain degree of particularity, it should be understood that various alterations and modifications could be made without departing from the spirit or scope of the invention as hereinafter claimed.