Tool holder having a vibration-proof structure with two masses and cutting tool provided in the tool holder

Abstract

The long tool holder (22) has a tool vibration isolation component that defines a mass housing portion (40) with a sealed internal cavity, and a vibration isolation structure (34) that occupies the sealed internal cavity. The vibration isolation structure includes two vibration absorbing masses (54a, 54b) disposed within the holder cavity and resiliently suspended therein by at least three resilient suspension members that contact the inwardly facing cavity walls. The two vibration absorbing masses are formed from different materials and have different lengths. The cutting tool (20) includes a tool holder.

Description

[Technical field]

[0001] The subject matter of this application relates generally to tool holders, and more particularly to such tool holders having vibration isolation structures, and more particularly to vibration isolation structures having two vibration absorbing masses. [Background technology]

[0002] To suppress vibrations of the toolholder during metal cutting operations, the toolholder may be provided with an anti-vibration structure, which is typically a spring-mass system including a cavity and a vibration-absorbing mass suspended within the cavity by elastic support members.

[0003] In one such vibration isolation arrangement, the spring-mass system may include two vibration absorbing masses. Examples of such tool holding systems are disclosed, for example, in U.S. Pat. No. 3,559,512, U.S. Pat. No. 3,690,414, U.S. Pat. No. 4,050,665, U.S. Pat. No. 4,130,185 and U.S. Pat. No. 4,903,785.

[0004] It is an object of the present subject matter to provide a new and improved vibration isolation structure. Summary of the Invention

[0005] According to a first aspect of the present subject matter, there is provided a tool holder elongated along its holder longitudinal axis defining opposite forward and rearward directions, said tool holder configured to be fixed at a rear end thereof, said tool holder comprising: a mass housing portion including an interior holder cavity having an inwardly facing cavity wall; A vibration isolation structure comprising: two vibration absorbing masses including a long vibration absorbing mass having a long mass central axis and a short vibration absorbing mass having a short mass central axis, each of the long vibration absorbing mass and the short vibration absorbing mass having axially opposed forward and rearward mass ends; At least three resilient suspension members: the elongated vibration absorbing mass extends along the elongated mass central axis a length of the elongated mass and comprises an elongated mass material; the short vibration absorbing mass extends along the short mass central axis a short mass axis length and comprises a short mass material; the short mass axial length is shorter than the long mass axial length, and the long vibration absorbing mass and the short vibration absorbing mass are formed from different materials; The tool holder is adjustable between an unassembled state and an assembled state, and in the assembled state: The two vibration absorbing masses are disposed within the internal holder cavity and comprise at least three elastic suspension members that are elastically suspended therein by at least three of the suspension members that contact the inward-facing cavity wall surfaces.

[0006] According to a second aspect of the present subject matter, there is provided a cutting tool comprising: a tool holder of the type described above; and a cutting portion (24) disposed at a front end of the tool holder, the cutting portion (24) comprising at least one cutting insert.

[0007] It will be understood that the above is a summary and that the features described below may be applied to the subject matter of the present application in any combination, for example any of the following features may be applicable to the tool holder or the cutting tool:

[0008] The long vibration absorbing mass and the short vibration absorbing mass may be axially offset along the holder longitudinal axis such that one of the long vibration absorbing mass and the short vibration absorbing mass is closer to the front end of the tool holder than the other.

[0009] The short vibration absorbing mass may be located closer to the front end of the tool holder than the long vibration absorbing mass.

[0010] One of the long and short vibration absorbing masses closer to the front end of the tool holder may have a density greater than a density of the other of the long and short vibration absorbing masses.

[0011] The long mass material may have a higher stiffness than the short mass material.

[0012] The at least three suspension members may comprise at least one central suspension member.The long vibration absorbing mass and the short vibration absorbing mass may be spaced apart by the at least one central suspension member.

[0013] The vibration isolation structure may comprise four suspension members including one suspension member arranged at a front mass end axially forward of the two vibration absorbing masses, another suspension member arranged at a rear mass end axially rearward of the two vibration absorbing masses, and two central suspension members separating the two vibration absorbing masses.

[0014] The two central suspension members may be in resilient contact with each other.

[0015] The vibration isolation structure may comprise exactly two vibration absorbing masses.

[0016] The long vibration absorbing mass may have a constant long mass cross-sectional area in a plane oriented perpendicular to the long mass central axis distal to a mass end of the long vibration absorbing mass. The short vibration absorbing mass may have a constant short mass cross-sectional area in a plane oriented perpendicular to the short mass central axis distal to a mass end of the short vibration absorbing mass. The long mass cross-sectional area may be the same as the short mass cross-sectional area.

[0017] Both vibration absorbing masses may have a cylindrical shape with the same diameter. In the assembled state, the long mass central axis and the short mass central axis may be aligned and share a common mass central axis parallel to the holder longitudinal axis.

[0018] The cutting portion may be removably attached to the tool holder.

[0019] For a better understanding of the present application, and to show how the same may be carried out in practice, reference will now be made to the accompanying drawings. [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 is a perspective view of a cutting tool according to the present application, showing a vibration isolation structure. [Diagram 2] FIG. 2 is an exploded perspective view of the cutting tool of FIG. 1 according to the present application. [Diagram 3] FIG. 2 is an axial cross-sectional view of the cutting tool of FIG. 1. [Figure 4] 4 is a radial cross-sectional view of the cutting tool of FIG. 1 taken along line IV-IV of FIG. 3. [Diagram 5] 4 is a radial cross-sectional view of the cutting tool of FIG. 1 taken along line VV of FIG. 3.

[0021] It will be understood that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, dimensions of some of the elements may be exaggerated relative to other elements for clarity or several physical components may be included in one functional block or element. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] In the following description, various aspects of the subject matter of the present application are described. For purposes of explanation, specific configurations and details are set forth in sufficient detail to provide a thorough understanding of the subject matter of the present application. However, it will be apparent to one skilled in the art that the subject matter of the present application may be practiced without the specific configurations and details presented herein.

[0023] Attention is first directed to FIG. 1, which illustrates one aspect of the present application, a cutting tool 20 for chip removal. The cutting tool 20 has a tool longitudinal axis A. According to certain embodiments of the present subject matter, the cutting tool 20 may be a fixed cutting tool. That is, the cutting tool 20 is not designed to rotate about a rotation axis. In this non-limiting example shown in the drawing, the cutting tool 20 is a boring bar. However, the present subject matter is not limited to boring bars, and may be applicable to turning tools in general, for example, but not limited to. The present subject matter may be applicable to rotary cutting tools, such as milling cutters and drills. For such rotary cutting tools, the cutting tool 20 is designed to be rotatable in a rotational direction about the tool longitudinal axis A.

[0024] The cutting tool 20 includes a tool holder 22. The cutting tool 20 also includes a cutting portion 24 that may include at least one cutting insert 26. The at least one cutting insert 26 is designed to perform a metal cutting operation and has a cutting edge for that purpose. According to certain embodiments of the subject matter of the present application, the at least one cutting insert 26 may be removably attached to the cutting portion 24. The cutting portion 24 may be integrally formed with the tool holder 22. Alternatively, as seen in the non-limiting example illustrated in the drawings, the cutting portion 24 may be removably attached to the tool holder 22. The cutting portion 24 may be disposed at a front end of the tool holder 22. The rear end of the tool holder 22 is configured to be secured by a retention device.

[0025] 2, an exploded view of a tool holder 22 according to another embodiment of the present invention is shown. The tool holder 22 is oriented in an opposite forward direction D. F and backward D RThe tool holder 22 has a holder longitudinal axis B that defines a length along the holder longitudinal axis B. According to certain embodiments of the present subject matter, the cutting tool 20 and the tool holder 22 may be coaxial with one another. It should be noted that two elements (e.g., the cutting tool 20 and the tool holder 22 in this case) are coaxial with one another if their longitudinal axes coincide (align with one another).

[0026] Additionally, it should be noted that the use of the terms "forward" and "rearward" throughout this description and claims refers to relative positions in the direction of the holder longitudinal axis B toward the left and right sides, respectively, of Figure 3. Generally, the forward direction is toward the cutting portion 24.

[0027] According to certain embodiments of the present subject matter, the tool holder 22 may include two opposing front and rear holder end faces 30F and 30R, respectively, and a holder peripheral surface 32 extending therebetween. The holder peripheral surface 32 may extend about the holder longitudinal axis B. In this non-limiting example shown in the drawings, one of the holder end faces 30 (e.g., the front holder end face 30F) is serrated for engaging a corresponding surface of the cutting portion 20.

[0028] The tool holder 22 includes a mass housing portion 40 and an anti-vibration structure 34. The tool anti-vibration structure 34 is designed to reduce or eliminate vibrations of the cutting tool 20 when the cutting tool 20 performs a metal cutting operation. According to certain embodiments of the present subject matter, the anti-vibration structure 34 may be located at a front end of the cutting tool 20.

[0029] The mass housing portion 40 has an internal holder cavity 36 formed therein. That is, the internal holder cavity 36 is enclosed within the mass housing portion 40. The holder cavity 36 is defined, at least in part, by an inwardly facing cavity wall 38. The cavity wall 38 separates the holder cavity 36 from the mass housing portion 40. The mass housing portion 40 surrounds the holder cavity 36. The holder cavity 36 has a cavity central axis D. According to certain embodiments of the present subject matter, the holder cavity 36 may be elongated along the cavity central axis D. The holder cavity 36 may be elongated in the same direction as the tool holder 22. In particular, the holder cavity 36 may be coaxial with the tool holder 22. The cavity wall 38 may include two opposing cavity wall end faces 42 and a cavity wall peripheral face 44 extending therebetween. The cavity wall peripheral surface 44 may extend about the central cavity axis D.

[0030] 3, an axial cross-section (along a plane including the cavity central axis D) of the holder cavity 36 is shown through a cavity wall peripheral surface 44, the holder cavity 36 having a cavity cross-section. According to an embodiment of the subject matter of the present application, the cavity cross-section may be uniform along the cavity central axis D. The cavity wall peripheral surface 44 may have a substantially cylindrical shape. The cavity wall peripheral surface 44 may have a cylindrical shape in the vicinity of the two cavity wall end faces 42 (where the cavity wall peripheral surface 44 abuts the suspension member 62, as described later in this description). The two cavity wall end faces 42 may be planar and oriented transversely to the cavity central axis D. The two cavity wall end faces 42 may be oriented perpendicularly to the cavity central axis D.

[0031] 1 and 2, the tool holder 22 also includes an anti-vibration structure 34 comprising a plurality of vibration absorbing masses 54a, 54b. Preferably, the anti-vibration structure 34 may include just two vibration absorbing masses 54a, 54b.

[0032] The two vibration absorbing masses 54a, 54b include a long vibration absorbing mass 54a made of a long mass material. The long vibration absorbing mass 54a extends along the long mass central axis E1 over a long mass axial length LL. The two vibration absorbing masses 54a, 54b also include a short vibration absorbing mass 54b made of a short mass material. The short vibration absorbing mass 54b extends along the short mass central axis E2 over a short mass axial length LS. The short mass axial length LS is shorter than the long axial length LL. The long mass material and the short mass material are different. That is, the long vibration absorbing mass 54a and the short vibration absorbing mass 54b are made of different materials. Preferably, both mass materials are non-magnetic. For example, the short mass material may be tungsten and the long mass material may be tungsten carbide. According to certain embodiments of the present subject matter, the long mass material may have a higher stiffness (i.e., a higher Young's modulus) than the short mass material, thereby reducing the likelihood that the long vibration absorbing mass 54a (which accounts for the majority of the axial length of the spring-mass system) will bend and potentially impact the cavity wall peripheral surface 44.

[0033] 2 and 3, each of the two vibration absorbing masses 54a, 54b has a corresponding mass central axis E1, E2. In the assembled tool holder 22, the mass central axes E1, E2 are coaxial, and the masses 54a, 54b share the same mass common central axis E. Each of the two vibration absorbing masses 54a, 54b includes two axially opposed mass ends 60a, 60b, a forward mass end 60a and a rearward mass end 60b, with the forward mass end 60a being forward of the rearward mass end 60b. The two axially opposed mass ends 60a, 60b are spaced apart from each other along the corresponding mass central axes E1, E2. According to an embodiment of the subject matter of the present application, each vibration absorbing mass 54a, 54b may include two opposing mass end faces 56 and a mass peripheral face 58 extending therebetween. The mass peripheral surface 58 may extend around the corresponding mass central axis E1, E2. The two mass end faces 56 are disposed at the two mass ends 60a, 60b, respectively. Each vibration absorbing mass 54a, 54b may be elongated along the corresponding mass central axis E1, E2. It should be noted that the long mass axial length LL and the short mass axial length LS are measured between the respective mass end faces 56 in the direction of the corresponding mass central axis E1, E2.

[0034] Referring to FIG. 4, a cross-sectional view of the tool holder is shown in a plane perpendicular to the holder longitudinal axis B through a central portion of the short vibration absorbing mass 54b (i.e., distal to the respective mass ends 60a, 60b), where the short vibration absorbing mass 54b may have a constant short mass cross-sectional area CS in a plane oriented perpendicular to the short mass central axis E2. Referring to FIG. 5, a cross-sectional view of the tool holder is shown in a plane oriented perpendicular to the holder longitudinal axis B through a central portion of the long vibration absorbing mass 54a (i.e., distal to the respective mass ends 60a, 60b) between the mass end faces 56, where the long vibration absorbing mass 54a may have a constant long mass cross-sectional area CL in a plane oriented perpendicular to the long mass central axis E1. The long mass cross-sectional area CL may be the same as the short mass cross-sectional area CS. Thus, in an embodiment in which the two masses 54a, 54b both have a cylindrical shape, they may have the same diameter.

[0035] 3, according to one embodiment of the present subject matter, the mass end faces 56 may be conically shaped, tapering inwardly away from the central portions of the vibration absorbing masses 54a, 54b. The mass peripheral faces 58 may have a cylindrical shape.

[0036] The vibration-proof structure 34 further includes at least three elastic suspension members 62. The at least three suspension members 62 are elastically deformable. According to some embodiments of the present subject matter, the at least three suspension members 62 may be formed from a material different from the material of the two vibration-absorbing masses 54a, 54b. In some embodiments, the suspension members 62 are formed from rubber having a durometer hardness of 60A to 95A. The at least three suspension members 62 may be O-rings.

[0037] The tool holder 22 is adjustable between an assembled state and an unassembled state. In the unassembled state of the tool holder 22, two vibration absorbing masses 54a, 54b are disposed outside the inner holder cavity 36.

[0038] According to one embodiment of the subject matter of the present application, and referring to FIG. 3, the tool holder 22 is R The tool holder 22 includes a cavity axial seal member 67 that defines (bounds) the holder cavity 36 and seals the holder cavity 36. That is, the cavity axial seal member 67 forms one of the cavity wall end faces 38. While the holder cavity 36 is not sealed by the cavity axial seal member 67 (i.e., while the tool holder 22 is in the unassembled position), the two vibration absorbing masses 54a, 54b may be inserted into the holder cavity 36. In the assembled state of the tool holder 22, the holder cavity 36 is sealed by the cavity axial seal member 67.

[0039] In the assembled state of the tool holder 22, the two vibration absorbing masses 54a, 54b are disposed within the holder cavity 36 and may share a common central axis E of the masses by being aligned with their respective central axes E1, E2.

[0040] According to certain embodiments of the present subject matter, the long vibration absorbing mass 54a and the short vibration absorbing mass 54b may be axially offset along the holder tool axis B. Thus, one of the long vibration absorbing mass 54a and the short vibration absorbing mass 54b is closer to the front end of the tool holder 22 than the other. Preferably, the short vibration absorbing mass 54b may be located closer to the front end of the tool holder 22 than the long vibration absorbing mass 54a. Testing has shown that having the shortest mass closest to the cutting zone improves the damping effect.

[0041] According to certain embodiments of the present subject matter, one of the long and short vibration absorbing masses 54a, 54b closer to the front end of the toolholder 22 comprises a first material having a first density greater than a second density of a second material comprising the other of the long and short vibration absorbing masses 54a, 54b. Thus, in configurations where the short vibration absorbing mass 54b is closer to the front end of the toolholder 22, the short mass material has a higher density than the long mass material, and where the long vibration absorbing mass 54a is closer to the front end of the toolholder 22, the long mass material has a higher density. It has been found that having the densest mass closer to the cutting zone improves damping.

[0042] According to an embodiment of the subject matter of the present application, in the assembled position of the tool holder 22, the two vibration absorbing masses 54a, 54b may be elongate in the same direction as the tool holder 22. That is, the mass common central axis E may be parallel to the holder longitudinal axis B, which axes B and E establish the longest main dimension of the tool holder 22 and the longest main dimension of the vibration absorbing masses 54a, 54b, respectively. In particular, the mass common central axis E may coincide with the holder longitudinal axis B (i.e., the two vibration absorbing masses 54a, 54b may be coaxial with the tool holder 22).

[0043] In the assembled position of the tool holder 22, the two vibration absorbing masses 54a, 54b are connected to the mass housing portion 40 via at least three suspension members 62. The two vibration absorbing masses 54a, 54b are thus elastically suspended within the holder cavity 36 by the at least three suspension members 62 in contact with the inwardly facing cavity wall surface 38. Each suspension member 62 may abut a respective mass end face 56. It should be noted that no portion of the mass peripheral surface 58 is in direct contact with the inwardly facing cavity wall surface 38. According to an embodiment of the present subject matter, each of the at least three suspension members 62 may undergo compressive elastic deformation due to contact against the inwardly facing cavity wall surface 38 and against one of the mass end faces 56.

[0044] According to an embodiment of the subject matter of the present application, the at least three suspension members may include at least one central suspension member, indicated by reference number 63. The long vibration absorbing mass 54a and the short vibration absorbing mass 54b may be spaced apart by and in contact with the at least one central suspension member 63. In this non-limiting example shown in the drawings, the vibration isolation structure 34 may include a total of four suspension members, with one suspension member 62 arranged at the forward mass end 60a of the axially forward one of the vibration absorbing masses and another suspension member 62 arranged at the rear mass end 60b of the axially rearward one of the vibration absorbing masses, and the two central suspension members 63 separating the two vibration absorbing masses 54a, 54b. The two central suspension members 63 may be in elastic contact with each other. Each of the two central suspension members 63 may be in contact with only one of the two vibration absorbing masses 54a, 54b.

[0045] The vibration-proof structure 34 includes a vibration space 68 formed in the holder cavity 36. The vibration space 68 is disposed between the two vibration-absorbing masses 54a, 54b and the mass housing portion 40 (more specifically, between the two vibration-absorbing masses 54a, 54b and the inward cavity wall surface 38). In other words, the mass housing portion 40 and the two vibration-absorbing masses 54a, 54b are separated by the vibration space 68. According to an embodiment of the subject matter of the present application, the vibration space 68 completely surrounds the two vibration-absorbing masses 54a, 54b in the circumferential direction. That is, the vibration space 68 may extend around the entire (360°) angular range of the cavity central axis D. Thus, the vibration space 68 may be considered as an annular vibration space surrounding the axial range of the two vibration-absorbing masses 54a, 54b.

[0046] The two vibration absorbing masses 54a, 54b are configured to vibrate in the vibration space 68 upon elastic deformation of the at least three suspension members 62. In other words, the two vibration absorbing masses 54a, 54b are capable of vibration displacement in the vibration space 68 when the at least three suspension members 62 are elastically deformed.

[0047] When the cutting tool 20 contacts a workpiece, the cutting tool 20 is subject to vibration. Typically, in the case of turning or milling cutting operations, the vibration is lateral. Typically, in the case of drilling cutting operations, the vibration is torsional. The two vibration-absorbing masses 54a, 54b vibrate at a certain vibration frequency. The vibration-proof structure 34 is designed to provide the two vibration-absorbing masses 54a, 54b with a vibration frequency that is close to, if not identical to, the natural frequency of the cutting tool 20, thereby reducing or eliminating the vibration of the cutting tool 20.

[0048] According to certain embodiments of the present subject matter, the vibrational space 68 may be empty. For example, the vibrational space 68 may be devoid of viscous fluid.

[0049] Although the subject matter of the present application has been described in some detail, it should be understood that various changes and modifications can be made without departing from the spirit or scope of the invention as hereinafter claimed.

Claims

1. Opposite forward direction (D Ｆ ) and a rear direction (D Ｒ ), a long tool holder (22) along the holder longitudinal axis (B) of the tool holder (22), wherein the tool holder (22) is configured to be fixed at the rear end of the tool holder (22), and the tool holder (22) is, A mass housing portion (40) having an internal holder cavity (36) with an inward-facing cavity wall surface (38); A vibration isolation structure (34), Including a long vibration absorption mass (54a) having a long mass central axis (E1) and a short vibration absorption mass (54b) having a short mass central axis (E2), each of the long vibration absorption mass (54a) and the short vibration absorption mass (54b) having front and rear mass ends (60a, 60b) opposite in the axial direction, two vibration absorption masses (54a, 54b); At least three elastic suspension members (62), The long vibration absorption mass (54a) extends along the long mass central axis (E1) over a long mass axis length (LL) and comprises a long mass material; The short vibration absorption mass (54b) extends along the short mass central axis (E2) over a short mass axis length (LS) and comprises a short mass material; The short mass axis length (LS) is shorter than the long mass axis length (LL), and the long vibration absorption mass (54a) and the short vibration absorption mass (54b) are formed from different materials; The tool holder (22) is adjustable between a non-assembled state and an assembled state, and in the assembled state, At least three elastic suspension members (62) by which two of the vibration absorption masses (54a, 54b) are disposed in the internal holder cavity (36) and elastically suspended in the internal holder cavity (36) by contacting the inward-facing cavity wall surface (38). A vibration isolation structure (34) comprising: A tool holder (22).

2. The tool holder (22) according to claim 1, wherein the long vibration absorption mass (54a) and the short vibration absorption mass (54b) are axially offset along the holder longitudinal axis (B) such that one of the long vibration absorption mass (54a) and the short vibration absorption mass (54b) is closer to the front end of the tool holder (22) than the other.

3. The tool holder (22) according to claim 2, wherein the short vibration absorption mass (54b) is disposed closer to the front end of the tool holder (22) than the long vibration absorption mass (54a).

4. Of the long vibration absorption mass (54a) and the short vibration absorption mass (54b), the one closer to the front end of the tool holder (22) has a density greater than that of the other of the long vibration absorption mass (54a) and the short vibration absorption mass (54b). The tool holder (22) according to claim 2.

5. The long mass material has higher rigidity than the short mass material. The tool holder (22) according to claim 1.

6. At least three of the suspension members (62) include at least one central suspension member (63). The long vibration absorption mass (54a) and the short vibration absorption mass (54b) are separated by at least one central suspension member (63). The tool holder (22) according to claim 1.

7. The vibration isolation structure (34) One suspension member (62) disposed at the front mass end (60a) in the axial direction of the front of the two vibration absorption masses (54a, 54b), Another suspension member (62) disposed at the rear mass end (60b) in the axial direction of the rear of the two vibration absorption masses (54a, 54b), The vibration isolation structure (34) includes four suspension members (62) including two central suspension members (63) that separate the two vibration absorption masses (54a, 54b). The tool holder (22) according to claim 6.

8. The two central suspension members (63) are in elastic contact with each other. The tool holder (22) according to claim 7.

9. The vibration isolation structure (34) includes exactly two vibration absorption masses (54a, 54b). The tool holder (22) according to claim 1.

10. The long vibration absorption mass (54a) has a constant long mass cross-sectional area (CL) in a plane oriented perpendicular to the long mass central axis (E1) distal to the mass ends (60a, 60b) of the long vibration absorption mass (54a). The short vibration absorption mass (54b) has a constant short mass cross-sectional area (CS) in a plane oriented perpendicular to the short mass central axis (E2) distal to the mass ends (60a, 60b) of the short vibration absorption mass (54b). The long mass cross-sectional area (CL) is the same as the short mass cross-sectional area (CS). The tool holder (22) according to claim 1.

11. Both vibration absorption masses (54a, 54b) have a cylindrical shape with the same diameter. In the assembled state, the long mass central axis (E1) and the short mass central axis (E2) are aligned and share a common mass central axis (E) parallel to the holder longitudinal axis (B), the tool holder (22) according to claim 1.

12. A tool holder (22) according to claim 1, a cutting portion (24) disposed at the front end of the tool holder (22), the cutting portion (24) comprising at least one cutting insert (26), a cutting tool (20).

13. The cutting tool (20) according to claim 12, wherein the cutting portion (24) is removably attached to the tool holder (22).

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