Cutting tool components

Abstract

A cutting tool assembly comprises a first tool part (1) and a second tool part (2). The first tool part comprises: a front end (5), the front end (5) comprising a cutting edge; and a rear end (6), the rear end (6) comprising a tapered section (7) and an engagement section (8). The second tool part comprises a tapered recess (11) and a clamping device (20) located behind the tapered recess. The clamping device is arranged in a transverse cavity (19) of the second tool part, and the clamping device comprises a first clamping block (21), a second clamping block (22) and a differential screw (23) engaged with the first clamping block and the second clamping block. When the first and second clamping blocks are moved toward each other by the differential screw, the first and second clamping blocks engage the engagement section of the first tool part to pull the first tool part into the tapered recess, and the differential screw protrudes rearward from the first and second clamping blocks.

Description

Technical Field

[0001] This invention generally relates to a cutting tool assembly, and more particularly to a rotary cutting tool assembly configured for machining elongated holes, i.e., relatively long and narrow holes, such as valve guides for internal combustion engines in the automotive industry. However, the invention is not limited to this specific application but can be applied to the machining of any elongated hole. In particular, the invention relates to a cutting tool assembly according to the preamble of claim 1. Background Art

[0002] DE 20 2015 104 652 discloses a rotary cutting tool assembly comprising: a first tool portion having a cutting edge; and a second tool portion releasably retaining the first tool portion. The first tool portion is elongated and extends along a longitudinal axis. The first tool portion includes a front end portion and a rear end portion, the front end portion including the cutting edge, and the rear end portion including: a tapered section that tapers away from the front end portion; and a joining section located behind the tapered section. The second tool portion includes: a tapered recess receiving the tapered section of the first tool portion; and a clamping device located behind the tapered recess.

[0003] The clamping device of DE 20 2015 104 652 includes a sleeve having a plurality of tongues extending longitudinally in a central hole of a second cutting tool portion. The tongues can clamp a joint section of the first cutting tool portion and can be pulled back to secure the first cutting tool portion in a recess of the second cutting tool portion. The pulling movement of the sleeve and the first cutting tool portion originates from the rear end of the second cutting tool portion, meaning the rear end must be accessible. Therefore, in practice, when the first cutting tool portion needs to be replaced or replaced, the second cutting tool portion needs to be removed from the machine tool.

[0004] Another drawback of existing rotary cutting tool assemblies is the relatively long axial length of the clamping device. The clamping device extends significantly rearward within the tool holder, which increases the overall length of the tool and adversely affects its usability. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned disadvantages and to provide a cutting tool assembly that can be easily disassembled and assembled and can be designed to have a shorter overall length.

[0006] This objective is achieved through a cutting tool assembly that is initially defined, characterized by:

[0007] The clamping device is disposed within the transverse cavity of the second cutting tool section, and the clamping device includes a first clamping block, a second clamping block, and a differential screw extending along the transverse axis and engaging with the first clamping block and the second clamping block, wherein the differential screw is configured to allow the first clamping block and the second clamping block to move away from each other and toward each other parallel to the transverse axis.

[0008] The first and second clamping blocks include corresponding engagement surfaces arranged to engage the engagement segment of the first tool portion when the tapered segment is placed in the tapered recess, so that when the first and second clamping blocks move toward each other, the first tool portion is pulled into a holding position in the tapered recess, and

[0009] Each of the first and second clamping blocks includes a corresponding threaded channel that extends parallel to the transverse axis and receives a differential screw that protrudes rearward from the first and second clamping blocks beyond the threaded channel.

[0010] According to the present invention, the differential screw of the clamping device is accessible from the side of the second tool part. Therefore, it can be manipulated and rotated in the clamping direction from the side of the second tool part to move the first and second clamping blocks into engagement with the engagement section of the first tool part. Replacing the first tool part does not require access to the second tool part from the rear. Therefore, the second tool part can remain in the machine tool or form an integral part of the machine tool while the first tool part is being replaced. This allows for faster replacement of the first tool part, such as a reamer.

[0011] Furthermore, due to the construction of the prominent differential screw, the clamping device can have a significantly shortened axial length, thus contributing to a compact and axially shorter design for the second tool section. The first and second clamping blocks do not necessarily need to extend axially beyond the differential screw.

[0012] According to one embodiment of the invention, the transverse cavity of the second cutting tool portion extends through the second cutting tool portion in the transverse direction. Therefore, the differential screw can be accessed from both opposite sides of the second cutting tool portion.

[0013] According to one embodiment of the present invention, the second tool portion may include or constitute a tool holder, or may be an integral part of the machine tool.

[0014] According to one embodiment of the invention, the first tool portion may be elongated. The axial length of the first tool portion can therefore be the cutting diameter D. C At least 2, 3, 4, 5, 6, 7, 8, 9, 10, or more times. Cutting diameter D C It is defined as twice the distance between the longitudinal axis and the cutting edge of the first tool section.

[0015] According to one embodiment of the present invention, each threaded channel has an elongated opening extending parallel to the transverse axis through the rear ends of the first and second clamping blocks, respectively, wherein the differential screw protrudes rearwardly through the opening.

[0016] According to one embodiment of the invention, viewed in a plane perpendicular to the transverse axis, each threaded channel has a central angle β, a first ray of which intersects a first edge of the elongated opening, and a second ray of which intersects a second edge of the elongated opening, wherein 180° < β < 360°. The vertex of angle β is located on the central axis of the threaded channel. This configuration of channels with a central angle of 180° < β < 360° can help to significantly shorten the length of the first and second clamping blocks compared to clamping blocks with cylindrical threaded channels having a full circumference (i.e., threaded channels with angle β equal to 360°). More preferably, 200° ≤ β ≤ 330°, even more preferably, 220° ≤ β ≤ 300°, and most preferably, β = 240°. When 200° ≤ β, it is advantageous to assemble the differential screw into the clamping block. When 220° ≤ β, it is significantly easier to assemble the clamping device into the second tool portion. When β≤330°, the clamping block is shortened more significantly and is easy to manufacture. When β≤300°, the width of the elongated opening is easier to control.

[0017] According to one embodiment of the invention, the clamping device includes a resilient retaining ring extending around a second cutting tool portion and first and second clamping blocks, wherein the retaining ring holds the first and second clamping blocks within a transverse cavity of the second cutting tool portion. This is particularly advantageous when the transverse cavity extends through the second cutting tool portion, and when the transverse cavity extends through only one side of the second cutting tool portion.

[0018] According to one embodiment of the invention, the retaining ring is arranged in a circumferential groove of the second tool part. Said circumferential groove may extend over the transverse cavity.

[0019] According to one embodiment of the invention, the differential screw includes a first threaded portion that mates with a threaded channel of a first clamping block and a second threaded portion that mates with a threaded channel of a second clamping block, wherein at least one of the first and second threaded portions protrudes rearward from the respective first and second clamping blocks beyond the respective threaded channels. Therefore, at least one of the first and second threaded portions may have a section located behind the respective clamping block. As described above, the first and second clamping blocks can thus have a shorter axial length. Advantageously, both the first and second threaded portions protrude beyond the respective threaded channels.

[0020] According to one embodiment of the invention, a cutting tool assembly includes a coolant system for supplying coolant to the cutting edge, wherein the coolant system includes a first central channel penetrating a first tool portion and a second central channel penetrating a second tool portion, wherein the clamping device and / or transverse cavity is configured to allow coolant to flow through the second central channel into the first central channel. The coolant can thus bypass the differential screw, and preferably through the gap in the transverse cavity between the first and second clamping blocks. When viewed along the transverse axis, the transverse cavity may have a shape concentric with the shape of the clamping device. Therefore, coolant loss is minimized during machining without coolant, and contamination of the clamping device is also minimized. A seal may also be provided between the clamping device and the transverse cavity, or the transverse cavity may be sealed. Therefore, proper cooling of the cutting edge and the workpiece can be ensured.

[0021] According to one embodiment of the invention, the differential screw includes a restricted intermediate portion located between a first threaded portion and a second threaded portion, wherein coolant is allowed to flow through a second central channel into a first central channel, thereby bypassing the restricted intermediate portion of the differential screw.

[0022] According to one embodiment of the invention, the joint segment includes a first lateral groove and a second lateral groove, which are separated from each other and positioned radially opposite to each other, and both the first and second lateral grooves include corresponding inclined front surfaces facing the tapered segment. By providing such lateral grooves, high strength of the joint segment can be ensured. In particular, strength can be increased compared to a single circumferential groove that extends fully around the joint segment.

[0023] According to one embodiment of the invention, the first and second clamping blocks include corresponding engagement surfaces that engage the respective inclined front surfaces of the inclined front surfaces when the first and second clamping blocks move toward each other, so as to pull the first tool portion into a holding position in the tapered recess. The engagement surfaces of the first and second clamping blocks may be inclined rearward toward the differential screw and face it. Advantageously, the engagement surfaces of the first and second clamping blocks may be inclined at an angle corresponding to the angle of the inclined front surface of the corresponding transverse recess.

[0024] According to one embodiment of the present invention, when viewed along the direction from the first transverse groove to the second transverse groove, each of the first transverse groove and the second transverse groove has a bottom line perpendicular to the longitudinal axis.

[0025] In one embodiment of the invention, the aforementioned bottom line is convexly curved. The convexly curved bottom line can help further ensure the strength of the joint section of the first cutting tool portion.

[0026] According to one embodiment of the invention, the radius of curvature of the bottom line is longer than the minimum radial distance from the bottom line to the longitudinal axis.

[0027] According to one embodiment of the invention, the engagement segment includes two inclined rear surfaces facing away from the tapered segment and configured to engage with corresponding front surfaces of the first and second clamping blocks to push the first cutting tool portion out of its holding position in the tapered recess as the first and second clamping blocks move away from each other. The first cutting tool portion can thus be pushed out of the tapered recess of the second cutting tool portion against frictional forces between the tapered segment and the tapered recess by rotating the differential screw in a release direction opposite to the clamping direction. These forces can be large, especially when the taper angle of the tapered segment of the first cutting tool portion is small. The inclined rear surfaces can be positioned opposite corresponding inclined front surfaces of the first and second transverse recesses and can be formed by the rear end side of the engagement segment of the first cutting tool portion. The configuration with the two transverse recesses, combined with the function provided by the inclined rear surfaces and corresponding front surfaces of the first and second clamping blocks, can be particularly advantageous because, compared to a configuration with only a single circumferential recess extending fully around the engagement segment, the loss of debris or fragments from the engagement segment can be avoided, or this can occur less frequently.

[0028] In one embodiment of the present invention, the tapered section of the rear portion of the first tool part has a taper angle α, wherein 0.5°≤α≤10°.

[0029] According to one embodiment of the invention, the rear end of the first cutting tool portion includes at least one axial groove extending along a tapered section, wherein the tapered recess of the second cutting tool portion includes at least one axial groove, wherein a pin is disposed in the at least one axial groove of the second cutting tool portion, and the pin is arranged to engage with the at least one axial groove of the first cutting tool portion when the first cutting tool portion is mounted in the second cutting tool portion, to allow torque transmission between the second cutting tool portion and the first cutting tool portion. Preferably, the central axis of the at least one pin is parallel to the longitudinal axis of the first cutting tool portion. Furthermore, preferably, the extending direction of the at least one axial groove extending along the tapered section is parallel to the longitudinal axis of the first cutting tool portion. Advantageously, the rear end of the first cutting tool portion includes three axial grooves that engage with corresponding pins disposed in corresponding axial grooves of the tapered recess of the second cutting tool portion.

[0030] According to one embodiment of the present invention, the front end portion of the first cutter part is formed integrally with the rear end portion of the first cutter part.The front end portion may comprise an elongated cutter shaft.

[0031] According to one embodiment of the invention, the first tool part comprises or constitutes a reamer.

[0032] According to one embodiment of the invention, the second tool portion includes at least one cutting edge. The cutting edge of the second tool portion can be used to machine the valve seat of an internal combustion engine, while the cutting edge of the first tool portion can be used to simultaneously machine the valve guide of the internal combustion engine. The cutting tool assembly is preferably a tool for machining both the valve seat and the valve guide. Attached Figure Description

[0033] The invention will now be explained in more detail through description of various embodiments and with reference to the accompanying drawings.

[0034] Figure 1 A perspective view of a disassembled cutting tool assembly according to one embodiment of the present invention is disclosed.

[0035] Figure 2 A perspective view of a cutting edge of a first tool portion of a cutting tool assembly is disclosed.

[0036] Figure 3 A front view of a cutting tool assembly in an assembled state is disclosed, with a cross section through a first tool part.

[0037] Figure 4 A longitudinal section of the clamping device for the cutting tool assembly during clamping operation is disclosed.

[0038] Figure 5 A longitudinal cross-section of the clamping device during a releasing operation is disclosed.

[0039] Figure 6 Public Figure 4 and Figure 5 Exploded longitudinal section of the clamping device in FIG.

[0040] Figure 7 A rear side view of the first tool section of the cutting tool assembly is disclosed.

[0041] Figure 8 Publicly available along Figure 7 Section along line VIII-VIII in FIG.

[0042] Figure 9a A perspective view of the first clamping block of the clamping device is disclosed.

[0043] Figure 9b Another perspective view of the first clamping block is disclosed.

[0044] Figure 9c A perspective view of the second clamping block of the clamping device is disclosed.

[0045] Figure 9d Another perspective view of the second clamping block is disclosed.

[0046] Figure 10a Public Figure 9a Side view of the first clamping block in FIG.

[0047] Figure 10b Public Figure 9a Front view of the first clamping block in.

[0048] Figure 10c discloses Figure 9b Side view of the second clamping block in FIG.

[0049] Figure 10d has been released. Figure 9b Front view of the second clamping block in .

[0050] Figure 10e discloses Figure 9a A top view of the first clamping block in FIG.

[0051] Figure 11 An exploded perspective view of a clamping device is disclosed.

[0052] Figure 12 A top view of the clamping device in its disassembled state has been released.

[0053] Figure 12a A top view of the clamping device in a partially assembled state has been disclosed.

[0054] Figure 12b A top view of the clamping device in its assembled state is disclosed. DETAILED DESCRIPTION

[0055] Figure 1 A cutting tool assembly is disclosed, particularly a rotary cutting tool assembly, which is received by a machine tool (not disclosed) to rotate the cutting tool assembly. It should be noted that the cutting tool assembly can also be used as a stationary tool, wherein the workpiece (not disclosed) moves, for example, rotates.

[0056] The cutting tool assembly includes a first tool portion 1 and a second tool portion 2. In the disclosed embodiments, the first tool portion 1 constitutes or includes a reamer having at least one cutting edge 3, see also Figure 2 The second tool portion 2 constitutes or includes a tool holder, which is configured to releasably retain the first tool portion 1.

[0057] In the disclosed embodiments, the second tool portion 2 includes a rear engagement section 4 to be received in the machine tool. Alternatively, the second tool portion 2 may be integrally formed into the machine tool.

[0058] When assembling the cutting tool assembly, the first tool portion 1 and the second tool portion extend along the longitudinal axis x. The first tool portion 1 is elongated and may have an axial length that is at least 2, 3, 4, 5, 6, 7, 8, 9, 10, or more times the cutting diameter. The cutting diameter is defined as twice the distance between the longitudinal axis x and the cutting edge 3 of the first tool portion 1.

[0059] The first tool portion 1 includes a front end portion 5 and a rear end portion 6, the front end portion 5 including a cutting edge 3. The front end portion 5 includes or forms an elongated tool shaft with the cutting edge 3. The cutting edge 3 may be made of a hard metal insert that is seated in the tool holder of the front end portion 5 (e.g., removably attached or welded to the tool holder), or may be integrally formed with the front end portion 5.

[0060] See also Figure 7 The rear end portion 6 includes: a tapered section 7 that tapers away from the front end portion 5; and a joining section 8 located behind the tapered section 7.

[0061] In the disclosed embodiments, the front end portion 5 of the first cutting tool portion 1 and the rear end portion 6 of the first cutting tool portion 1 are integrally formed.

[0062] See also Figure 4 and Figure 5 The second cutting tool portion 2 includes a tapered recess 11 to receive the tapered segment 7 of the first cutting tool portion 1. For example... Figure 1 It can be seen that the second tool part 2 may also include at least one cutting edge 12.

[0063] The cutting tool assembly is designed for machining elongated holes, i.e., relatively long and narrow holes, such as valve guides for internal combustion engines in the automotive industry, using the cutting edge 3 of the first tool part 1. Due to the elongated shape of the first tool part 1, the first tool part 1 is suitable for insertion into the valve guide. In the same machining operation, and therefore simultaneously, the cutting tool assembly allows machining of a valve seat extending around the valve guide using the cutting edge 12 of the second tool part 2.

[0064] See also Figure 7 The tapered section 7 of the rear end portion 6 of the first cutting tool portion 1 has a tapered angle α, wherein 0.5°≤α≤10°, preferably 0.5°≤α≤7°, and more preferably 0.5°≤α≤4°. Figure 6 As shown, the tapered recess 11 of the second cutting tool portion can have a tapered angle of the same size as the tapered angle α.

[0065] Therefore, the cone angle α is relatively small, which means that the friction between the tapered section 7 and the tapered recess 11 can be large. The small cone angle α means that there is no axial stop between the first tool section 1 and the second tool section 2.

[0066] See also Figure 7 and Figure 8 In the disclosed embodiment, the rear end portion 6 of the first cutting tool portion 1 includes three axial grooves 13 extending along the tapered section 7. See also Figure 3 and Figure 6 The tapered recess 11 of the second cutting tool portion 2 includes three corresponding axial grooves 14, which are positioned opposite to corresponding grooves 13 when the first cutting tool portion 1 is installed in the second cutting tool portion 2. A pin 15 is disposed in each axial groove 14 of the second cutting tool portion 2, and when the first cutting tool portion 1 is installed in the second cutting tool portion 2, the pin 15 engages with the opposite axial groove 13 of the first cutting tool portion 1 to allow torque transmission between the second cutting tool portion 2 and the first cutting tool portion 1. See also Figure 4 and Figure 5 The pins 15 are held in place in their respective axial grooves 14 by means of internal retaining rings 16.

[0067] The second cutting tool portion 2 includes a clamping device 20 located behind the tapered recess 11 of the second cutting tool portion 2. More precisely, the clamping device 20 is disposed within the transverse cavity 19 of the second cutting tool portion 2. In the disclosed embodiments, such as Figures 4 to 6 As can be seen, the transverse cavity 19 is located behind and adjacent to the conical recess 11, and the transverse cavity 19 extends through the second cutting tool portion 2, that is, it completely passes through the second cutting tool portion 2.

[0068] The clamping device 20 includes a first clamping block 21, a second clamping block 22, and a differential screw 23. The differential screw 23 extends along a transverse axis y that is perpendicular to the longitudinal axis x.

[0069] Differential screw 23 engages first and second clamping blocks 21 and 22. Differential screw 23 is configured to move the first and second clamping blocks 21 and 22 away from each other and toward each other parallel to the transverse axis y.

[0070] The first clamping block 21 includes a threaded channel 21a extending parallel to and penetrating the first clamping block 21. The second clamping block 22 includes a threaded channel 22a extending parallel to and penetrating the second clamping block 22.

[0071] The differential screw 23 includes: a first threaded portion 24, which mates with the threaded channel 21a of the first clamping block 21; and a second threaded portion 25, which mates with the threaded channel 22a of the second clamping block 22. The first threaded portion 24 and the threaded channel of the first clamping block 21 may be left-hand threads, while the second threaded portion 25 and the threaded channel of the second clamping block 22 may be right-hand threads, or vice versa.

[0072] Furthermore, the differential screw 23 can include a constrained intermediate portion 26 located between the first threaded portion 24 and the second threaded portion 22. In the disclosed embodiment, the constrained intermediate portion 26 has a smaller diameter than the first threaded portion 24 and the second threaded portion 25.

[0073] The differential screw 23 may also have at least one engagement insert 27 for receiving a tool for rotating the differential screw 23. In the disclosed embodiment, one engagement insert 27 extends from the first end of the differential screw 23 within the first threaded portion 24. Figure 1 Combine Figures 4 to 6 As can be seen, the engagement insert 27 can be easily accessed from the outside of the cutting tool assembly by a suitable tool.

[0074] See also Figure 6 、 Figure 10a As shown in Figure 10c, the first clamping block 21 and the second clamping block 22 include corresponding engagement surfaces 21b and 22b, which are arranged to engage the engagement segment 8 of the first cutting tool portion 1 when the tapered segment 7 is placed in the tapered recess 11 of the second cutting tool portion 2. When the first and second clamping blocks 21, 22 are moved toward each other by rotating the differential screw 23, the first cutting tool portion 1 can be pulled into the holding position in the tapered recess 11 of the second cutting tool portion 2.

[0075] like Figure 4-6 、 Figure 11 、 Figure 12 、 Figure 12a and Figure 12b As can be seen, the differential screw 23 protrudes rearward from the first and second clamping blocks 21 and 22 beyond the threaded channels 21b and 22b.

[0076] In the disclosed embodiment, the threaded channel 21a of the first clamping block 21 and the threaded channel 22a of the second clamping block 22 have corresponding elongated openings 21c and 22c, see Figure 9a 、 Figure 9c 10e. The elongated openings 21c, 22c extend parallel to the transverse axis through the rear ends of the first and second clamping blocks 21, 22, respectively. The differential screw 23 protrudes rearward through the openings 21c, 22c, which allows the clamping device 20 to be designed with a shorter axial length. Figure 12 As can be seen, the transverse cavity 19 for accommodating the clamping device 20 can be formed by two overlapping holes extending radially through the second tool part 2. The first rear hole can accommodate the protruding portion of the differential screw 23, while the second front hole can accommodate the clamping blocks 21, 22. The diameter of the first hole is smaller than the diameter of the second hole.

[0077] As shown in Figure 10e, viewed along a plane perpendicular to the transverse axis y, each of the threaded channels 21a and 22a can have a central angle β. The first ray of this central angle β intersects the first edge of the elongated openings 21c and 22c, while the second ray of this central angle β intersects the second edge of the elongated openings 21c and 22c, wherein 180° < β < 360°, preferably 200° ≤ β ≤ 320°, and more preferably 220° ≤ β ≤ 300°. In the disclosed embodiment, β = 240°. The central angle β of the threaded channel 22a of the second clamping block 22 can be equal to the central angle length β of the first clamping block 21.

[0078] The central angle β should be large enough to ensure that the differential screw 23 is retained in the threaded channels 21 a , 22 a , but short enough to allow a short axial length and compactness of the clamping device 20 .

[0079] See also Figure 1 、 Figure 4 、 Figure 5 and Figure 12b In order to retain the clamping device 20 in the transverse cavity 19 of the second tool part 2, an elastic retaining ring 28 can be provided, and the elastic retaining ring 28 extends around the second tool part 2 and the first and second clamping blocks 21, 22. The retaining ring 28 can be arranged in a circumferential groove 29 of the second tool part 2. In particular, Figure 11 and Figure 12 It can be seen that the circumferential groove 29 can be axially positioned at the transverse cavity 19, in particular at the front end of the transverse cavity 19. Figure 11 , the retaining ring 28 may be a split ring having a short gap 30 between two adjacent ends of the retaining ring 28 .

[0080] The first clamping block 21 may include a recess 31 in a radially outer surface of the first clamping block 21. The recess 31 may be designed to receive a portion of the retaining ring 28 when the first clamping block 21 is disposed in the transverse cavity 19.

[0081] In the same manner, the second clamping block 22 may include a recess 32 in a radially outer surface of the second clamping block 22. The recess 32 may be designed to receive an opposing portion of the retaining ring 28 when the second clamping block 22 is positioned in the transverse cavity 19.

[0082] Compared to the recess 32 of the second clamping block 22, the recess 31 of the first clamping block 21 may have a protrusion 33 located at the center of the recess 31. The protrusion 33 may be designed to extend into the gap 30 of the retaining ring 28 when the retaining ring 28 is set in the circumferential groove 29.

[0083] In the disclosed embodiment, the engagement section 8 of the rear end 6 of the first tool part 1 comprises a first transverse groove 36 and a second transverse groove 37, see Figure 7 and Figure 8 The transverse grooves 36, 37 are separated from each other and are positioned radially opposite each other. The transverse grooves 36, 37 may comprise respective inclined front surfaces 36a, 37a facing the conical section 7. Figure 7 As can be seen, in the disclosed embodiment, the inclined front surfaces 36a, 37 form an angle of 40° with the transverse axis y. The transverse grooves 36, 37 can ensure high strength of the joint section 8. In particular, the strength can be increased compared to only one circumferential groove extending completely around the joint section.

[0084] When viewed in a direction from the first transverse groove 36 to the second transverse groove 37, each of the first transverse groove 36 and the second transverse groove 37 may have a bottom line 36b, 37b perpendicular to the longitudinal axis x. Figure 8 As shown, the bottom lines 36b, 37b may be convexly curved. When a large tensile force is applied to the engaging section 8 and the first and second transverse grooves 36, 37, the convexly curved bottom lines 36b, 37b may help further ensure the strength of the engaging section 8 of the first tool part 1. The bottom lines 36b, 37b may have a curvature radius R that is longer than the minimum radial distance from the bottom lines 36b, 37b to the longitudinal axis x.

[0085] In the disclosed embodiments, such as Figure 4 and Figure 5 As shown, the engagement surfaces 21b, 22b of the first and second clamping blocks 21, 22 can engage respective ones of the inclined front surfaces 36a, 37a. Figure 6 The engagement surfaces 21b, 22b are formed by corresponding recesses 21d, 22d. Each recess 21d, 22d may have a midplane that forms an angle of approximately 40° with the transverse axis y. The engagement surfaces 21d, 22d may form an angle of approximately 15° with the midplane.

[0086] When the first and second clamping blocks 21 and 22 move toward each other by rotating the differential screw 23, see Figure 4 , the engagement surface 21b of the first clamping block 21 engages the inclined front surface 36a of the first transverse groove 36, and the engagement surface 22b engages the inclined front surface 37a of the second transverse groove 37, wherein further movement of the first and second clamping blocks 21, 22 can pull the first tool part 1 into the holding position in the conical recess 11.

[0087] In addition, see Figure 7, the engagement section 8 may comprise two inclined rear surfaces 38, 39 facing away from the tapered section 7. In the disclosed embodiment, the inclined rear surfaces 38, 39 are provided on a rear end surface of the rear end portion 6 of the first tool part 1 .

[0088] Each clamping block 21, 22 may also include a respective front surface 21e, 22e facing the outer end of the tapered recess 11. In the disclosed embodiment, the front surface 21e of the first clamping block 21 is positioned opposite the engagement surface 21c in the recess 21d, while the front surface 22e of the second clamping block 22 is positioned opposite the engagement surface 22c in the recess 22d.

[0089] When the first and second clamping blocks 21, 22 move away from each other, the rear surface 38 is configured to engage the front surface 21e of the first clamping block 21, while the rear surface 39 is configured to engage the front surface 22e of the second clamping block 22. Figure 5 The first cutting tool portion 1 can be pushed out of the holding position in the tapered recess 11.

[0090] The cutting tool assembly may also include a coolant system for supplying coolant to the cutting edge 3. See also Figure 1 The coolant system includes a first central channel 41 extending through the first tool portion 1 and a second central channel 42 extending through the second tool portion 2. The clamping device 20 may be configured to allow coolant to flow through the second central channel 42 into the first central channel 41 to an opening adjacent to the cutting edge 3, see Figure 2 This allows it to bypass the restricted middle portion 26 of the differential screw 23.

[0091] See also Figure 1 The coolant system may also include a coolant conduit from the second central channel 42 to an opening adjacent to the cutting edge 12.

[0092] The present invention is not limited to the disclosed embodiments, but can be varied and modified within the scope of the appended claims.

Claims

1. A cutting tool assembly comprising: A first tool part (1), the first tool part (1) having at least one cutting edge (3); and a second tool part (2) for releasably holding the first tool part (1), The first tool part (1) extends along a longitudinal axis (x), wherein the first tool part (1) comprises: a front end (5), the front end (5) comprising the at least one cutting edge (3); and a rear end (6), the rear end (6) comprising a tapered section (7) tapering away from the front end (5) and a joining section (8) located behind the tapered section (7), The second tool part (2) comprises: a conical recess (11), the conical recess (11) being used to accommodate the conical section (7) of the first tool part (1); and a clamping device (20), the clamping device (20) being located behind the conical recess (11), It is characterized in that The clamping device (20) is arranged in a transverse cavity (19) of the second tool part (2), and the clamping device (20) comprises a first clamping block (21), a second clamping block (22) and a differential screw (23), wherein the differential screw (23) extends along a transverse axis (y) and engages the first clamping block (21) and the second clamping block (22), wherein the differential screw (23) is configured to move the first clamping block (21) and the second clamping block (22) away from each other and towards each other parallel to the transverse axis (y), The first clamping block (21) and the second clamping block (22) comprise respective engagement surfaces (21b, 22b) arranged to engage the engagement section (8) of the first tool part (1) when the conical section (7) is placed in the conical recess (11) so as to draw the first tool part (1) into a holding position in the conical recess (11) when the first clamping block (21) and the second clamping block (22) are moved towards each other, and Each of the first clamping block (21) and the second clamping block (22) comprises a corresponding threaded channel (21a, 22a), which extends parallel to the transverse axis (y) and receives the differential screw (23), which protrudes rearwardly from the first clamping block (21) and the second clamping block (22) beyond the threaded channel (21a, 22a).

2. The cutting tool assembly according to claim 1, wherein: Each of the threaded channels (21a, 22a) has an elongated opening (21c, 22c), which extends parallel to the transverse axis (y) through the rear ends of the first clamping block (21) and the second clamping block (22), respectively, and wherein the differential screw (23) protrudes rearwardly through the elongated opening (21c, 22c).

3. The cutting tool assembly according to claim 2, wherein: Viewed in a plane perpendicular to the transverse axis (y), each of the threaded channels (21a, 22a) has a central angle β, a first ray of the central angle β intersects a first edge of the elongated opening (21c, 22c), and a second ray of the central angle β intersects a second edge of the elongated opening (21c, 22c), and wherein 180°<β<360°.

4. The cutting tool assembly according to any one of claims 1 to 2, wherein: The clamping device (20) comprises an elastic retaining ring (28) which extends around the second tool part (2) and the first clamping block (21) and the second clamping block (22), and wherein the elastic retaining ring (28) retains the first clamping block (21) and the second clamping block (22) in the transverse cavity (19) of the second tool part (2).

5. The cutting tool assembly according to any one of claims 1 to 2, wherein: The differential screw (23) comprises: a first threaded portion (24), the first threaded portion (24) cooperating with the threaded channel (21a) of the first clamping block (21); and a second threaded portion (25), the second threaded portion (25) cooperating with the threaded channel (22a) of the second clamping block (22), and wherein at least one of the first threaded portion (24) and the second threaded portion (25) protrudes backward from the corresponding first clamping block (21) and the second clamping block (22) to outside the corresponding threaded channel (21a, 22a).

6. The cutting tool assembly according to claim 5, wherein: The cutting tool assembly comprises a coolant system for supplying coolant to the cutting edges (3, 12), wherein the coolant system comprises a first central channel (41) extending through the first tool part (1) and a second central channel (42) extending through the second tool part (2), and wherein the clamping device (20) and / or the transverse cavity (19) are configured to allow coolant to flow through the second central channel (42) into the first central channel (41).

7. The cutting tool assembly according to claim 6, wherein: The differential screw (23) includes a restricted intermediate portion (26) between the first threaded portion (24) and the second threaded portion (25), and wherein the coolant is allowed to flow through the second central passage (42) into the first central passage (41), thereby bypassing the restricted intermediate portion (26) of the differential screw (23).

8. The cutting tool assembly according to any one of claims 1 to 2, wherein: The engagement section (8) comprises a first transverse groove (36) and a second transverse groove (37), the first transverse groove (36) and the second transverse groove (37) being separated from each other and positioned radially opposite to each other, and the first transverse groove (36) and the second transverse groove (37) comprising respective inclined front surfaces (36a, 37a) facing the tapered section (7).

9. The cutting tool assembly according to claim 8, wherein: The first clamping block (21) and the second clamping block (22) include corresponding engagement surfaces (21b, 22b), and when the first clamping block (21) and the second clamping block (22) are moved toward each other, the corresponding engagement surfaces (21b, 22b) engage with the corresponding inclined front surface of the inclined front surfaces (36a, 37a) so as to pull the first tool part (1) into a holding position in the tapered recess (11).

10. The cutting tool assembly according to claim 8, wherein: When viewed in a direction from the first transverse groove (36) to the second transverse groove (37), each of the first transverse groove (36) and the second transverse groove (37) has a bottom line (36b, 37b) perpendicular to the longitudinal axis (x).

11. The cutting tool assembly according to claim 10, wherein: The bottom line (36b, 37b) is convexly curved.

12. The cutting tool assembly according to claim 11, wherein: The radius of curvature (R) of the bottom line (36b, 37b) is longer than the minimum radial distance from the bottom line (36b, 37b) to the longitudinal axis (x).

13. The cutting tool assembly according to any one of claims 1-2, wherein: The engagement section (8) comprises two inclined rear surfaces (38, 39) which face away from the tapered section (7) and are configured to engage with corresponding front surfaces (21e, 22e) of the first clamping block (21) and the second clamping block (22) so as to push the first tool part (1) out of a holding position in the tapered recess (11) when the first clamping block (21) and the second clamping block (22) move away from each other.

14. The cutting tool assembly according to any one of claims 1-2, wherein: The conical section (7) of the rear end (6) of the first tool part (1) has a cone angle α, wherein 0.5°≤α≤10°.

15. The cutting tool assembly according to any one of claims 1-2, wherein: The rear end portion (6) of the first tool part (1) comprises at least one first axial groove (13) extending along the tapered section (7), wherein the tapered recess (11) of the second tool part (2) comprises at least one second axial groove (14), and wherein a pin (15) is provided in the at least one second axial groove (14) of the second tool part (2), and the pin (15) is arranged to cooperate with the at least one first axial groove (13) of the first tool part (1) when the first tool part (1) is mounted in the second tool part (2) to allow torque transmission between the second tool part (2) and the first tool part (1).

16. The cutting tool assembly according to any one of claims 1-2, wherein: The front end portion (5) of the first cutter portion (1) is integrally formed with the rear end portion (6) of the first cutter portion (1).

17. The cutting tool assembly according to any one of claims 1-2, wherein: The first tool part (1) comprises a reamer.

18. The cutting tool assembly according to any one of claims 1-2, wherein: The second tool part (2) comprises at least one cutting edge (12).

19. The cutting tool assembly according to any one of claims 1-2, wherein: The cutting tool assembly is a rotating cutting tool assembly.

Images