Boring head

Abstract

A boring head (1) comprises: a tool body (10) that has an axial core (X) and that can be mounted such that the axial core (X) is coaxial with the rotation axis of a main spindle of a machine tool; a synchronization member (40) that is accommodated in the tool body (10) so as to be rotatable; and a plurality of cartridges (20) that are attached to an end surface (14a) of the tool body (10) on the side where the synchronization member (40) is accommodated, so as to be movable in a direction perpendicular to the axial core (X), and that can hold a cutting blade (30). The plurality of cartridges (20) have, on the bottom surface thereof positioned on the side facing the tool body (10), a plurality of engagement grooves (26) formed in a direction perpendicular to the movement direction of the cartridges (20). The synchronization member (40) has a plurality of columnar engagement pins (46) engaged with the plurality of engagement grooves (26), and each of the plurality of engagement pins (46) is disposed at a position rotationally symmetric with respect to the axial core (X).

Description

Boring head

[0001] The present disclosure relates to a boring head.

[0002] Conventionally, there are boring heads that are attached to machine tools. Boring heads are used for boring workpieces in which holes have already been formed by casting, drilling, or other processes to enlarge the hole diameter. When performing rough machining with a boring head, multiple cutting edges may be used.

[0003] Patent Document 1 discloses a boring head. The boring head includes a tool body, a pair of cartridges (cutter holders in Patent Document 1) attached to the tool body, and cutting blades (cutter inserts in Patent Document 1) attached to each of the pair of cartridges. The pair of cartridges are attached to a clamping surface of the tool body by clamp screws in positions offset 180 degrees from each other. Each of the pair of cartridges is slidably attached so that the radial position of the cutting blade can be adjusted. The radial position of each of the pair of cartridges can be independently set by stoppers formed by set screws.

[0004] JP 2014-012339 A

[0005] When performing boring, the cutting blades attached to a pair of cartridges of the boring head must be positioned so that their radial distances from the rotation axis are equal. In the boring head disclosed in Patent Document 1, the pair of cartridges slide independently, so a dedicated adjustment device such as a tool presetter is usually used to adjust the radial position of each cutting blade. However, tool presetters are very expensive devices and are therefore only used by a limited number of users, with many users instead using calipers or micrometers. However, it is difficult to position a pair of independently movable cutting blades with a caliper or micrometer so that their radial distances from the rotation axis are equal, leaving room for improvement.

[0006] Therefore, there is a demand for a boring head that can easily equalize the radial distances of a plurality of cutting edges relative to the rotation axis when performing boring.

[0007] One embodiment of the boring head according to the present disclosure comprises a tool body having an axis and mountable so that the axis is coaxial with the rotational axis of a spindle of a machine tool; a synchronizer member housed in the tool body so as to be coaxial with the axis and rotatable within the tool body; and a plurality of cartridges movably attached to the end face of the tool body on the side where the synchronizer member is housed in a direction perpendicular to the axis and capable of holding cutting edges, each of the plurality of cartridges having an engagement groove formed in a direction perpendicular to the movement direction of the cartridge on a bottom surface located on the side opposite the tool body, the synchronizer member having a plurality of cylindrical engagement pins that engage with each of the plurality of engagement grooves, and each of the plurality of engagement pins being arranged in a position that is rotationally symmetrical with respect to the axis.

[0008] According to this embodiment, the multiple engagement pins of the synchronizing member are engaged with the respective engagement grooves of the multiple cartridges, so that the multiple cartridges can be moved synchronously by the movement of the synchronizing member. Also, because the multiple engagement pins of the synchronizing member are arranged at positions that are rotationally symmetrical about the axis, the movement distances of the multiple cartridges are always the same, and it is easy to make the distances from the axis of the cutting blades held in the multiple cartridges equal when performing boring.

[0009] In another embodiment of the boring head according to the present disclosure, the synchronizing member has a cylindrical main body and a flange extending radially outward from the main body, the outer surface of the main body is in sliding contact with the tool body, the outer surface of the flange is spaced from the tool body, and the engagement pin is arranged on the flange.

[0010] In this embodiment, the outer surface of the synchronizing member's body is in sliding contact with the tool body, while the outer surface of the flange is spaced from the tool body. This reduces friction when the synchronizing member rotates, allowing it to be rotated with a small force. Furthermore, because the engagement pins are located on the flange, which extends radially outward from the body, the multiple engagement pins move significantly in two dimensions even when the rotation angle of the synchronizing member is small. As a result, multiple pairs of cartridges can be moved significantly.

[0011] In another embodiment of the boring head according to the present disclosure, the multiple cartridges are configured to have a limited range of movement, and within the range of movement, the angle formed by a first imaginary line passing through the axis and parallel to the direction of movement of the cartridges, and a second imaginary line connecting the axis and the center of the engagement pin is greater than or equal to 15 degrees and less than or equal to 165 degrees.

[0012] According to this embodiment, the component of the force applied in the direction to move the cartridges that rotates the synchronizing member can be increased, so that multiple cartridges can be reliably moved.

[0013] In another embodiment of the boring head according to the present disclosure, the tool body has an accommodating hole that accommodates the synchronizing member, a plurality of female threads arranged around the accommodating hole for screwing together and fixing the plurality of cartridges, and a plurality of recesses formed between the inner surface of the accommodating hole and the inner surfaces of each of the plurality of female threads.

[0014] According to this embodiment, the tool body has multiple recesses between the inner circumferential surface of the receiving bore and the inner circumferential surfaces of the multiple female threads, and no inner circumferential surface exists at these locations. Therefore, even if the tool body has a thin wall between the inner circumferential surface of the receiving bore and the inner circumferential surfaces of the multiple female threads, the length of the thinned portion along the axis can be shortened. This allows the outer diameter of the synchronizer member to be increased while preventing cracks in the thinned portion. As a result, the engagement pin can be positioned further outward, and the travel distance of the engagement pin when the synchronizer member is rotated around the axis can be increased without increasing the outer diameter of the multiple cartridges or the tool body.

[0015] 1 is a front view showing a state in which a boring head according to this embodiment is attached to a machine tool; 2 is an exploded perspective view of the boring head; 3 is an exploded perspective view of the boring head; 4 is a longitudinal sectional view of the boring head; 5 is a plan view of a synchronizing member; 6 is a front view of a synchronizing member; 7 is a plan view showing the boring head in the minimum diameter state; and 8 is a plan view showing the boring head in the maximum diameter state.

[0016] Hereinafter, embodiments of the boring head according to the present disclosure will be described in detail with reference to the drawings. Note that the embodiments described below are examples for explaining the boring head, and the boring head is not limited to these embodiments. Therefore, the boring head can be embodied in various forms without departing from the spirit of the present invention.

[0017] As shown in Figure 1, a boring head 1 according to this embodiment is mounted on a tool holder 3 attached to a spindle of a machine tool 2 and used to perform boring. The boring head 1 has an axis X, and is mounted on the tool holder 3 with bolts 4 so that the axis X is coaxial with the rotation axis of the spindle. In other words, the axis X becomes the rotation axis during machining (when the spindle is rotating) while mounted on the machine tool 2. The boring head 1 rotates together with the spindle, and performs boring by using a cutting blade 30 to enlarge the inner diameter of an existing hole.

[0018] As shown in FIGS. 2 to 4 , the boring head 1 includes a tool body 10 , a pair of cartridges 20 , a pair of cutting blades 30 , and a synchronizing member 40 .

[0019] [Structure of Tool Body] The tool body 10 includes a held portion 12 that is held by the tool holder 3, and a main body portion 14 to which a pair of cartridges 20 are attached. The held portion 12 has a cylindrical shape, and the main body portion 14 has a columnar shape. The held portion 12 and the main body portion 14 have a common axis X.

[0020] Of the two end faces of the main body 14 perpendicular to the axis X, the tip end face 14a (an example of an end face) is the end face opposite the end facing the held portion 12. A first uneven portion 14b is formed by serration processing, and the first uneven portion 14b is a plurality of parallel uneven portions with a triangular wave cross section. In this embodiment, the groove depth of the first uneven portion 14b is all the same. Hereinafter, the extension direction of the first uneven portion 14b of the tool main body 10 will also be referred to as the Y direction.

[0021] A bottomed accommodation hole 16 having a circular cross section and coaxial with the axis X is formed from the tip surface 14a of the main body 14 toward the held portion 12. The accommodation hole 16 is a countersunk hole, and the inner diameter of the large diameter portion 16a located closer to the tip surface 14a is larger than the inner diameter of the small diameter portion 16b located farther from the tip surface 14a.

[0022] A pair of female threads 18 are formed around the periphery of the receiving hole 16, extending from the tip end surface 14a toward the held portion 12. The depth of the female threads 18 is greater than the depth of the receiving hole 16.

[0023] The pair of female threads 18 are arranged at positions that are point-symmetric, which is two-fold rotational symmetry with respect to the axis X. The pair of female threads 18 are arranged near the periphery of the large diameter portion 16a of the receiving hole 16, and a groove-like recess 19 (see FIG. 2) is formed between the inner circumferential surface of the large diameter portion 16a and the inner circumferential surfaces of the pair of female threads 18, with no inner circumferential surface present at that location. Note that "n-fold rotational symmetry" refers to a property whereby when rotated around a certain point (the axis X in this embodiment), a rotation of (360 / n) degrees results in the same shape as the original.

[0024] [Cartridge Structure] Next, the structure of the pair of cartridges 20 will be described. Each of the pair of cartridges 20 is configured to be movable in the Y direction perpendicular to the axis X relative to the tool body 10. Since each of the pair of cartridges 20 has the same shape, only one of the cartridges 20 will be described below.

[0025] The cartridge 20 is formed in a semi-cylindrical shape having a substantially semicircular shape when viewed in a direction along the axis X (hereinafter also referred to as a plan view). The diameter of the cartridge 20 is substantially equal to the diameter of the main body 14 of the tool body 10. A second uneven portion 20b, which is a plurality of parallel uneven portions having a triangular wave cross section, is formed by serration processing on the bottom surface 20a of the cartridge 20, which faces the main body 14 of the tool body 10. The pitch of the second uneven portion 20b is the same as the pitch of the first uneven portion 14b. Therefore, the cartridge 20 is attached to the tool body 10 such that the uneven portions of the second uneven portion 20b fit into the uneven portions of the first uneven portion 14b. This allows the cartridge 20 to slide only in the Y direction of the tool body 10.

[0026] The concaves and convexes of the second uneven portion 20b extend in a direction parallel to the linear portion (the portion forming the diameter of the semicircle) of the cartridge 20 in a plan view, i.e., in a direction parallel to the side surface 22 of the cartridge 20. As a result, when the second uneven portion 20b of the cartridge 20 slides over the first uneven portion 14b of the tool body 10, the cartridge 20 moves in a direction parallel to the side surface 22 (Y direction). The pair of cartridges 20 are attached to the main body 14 of the tool body 10 with a slight gap between their respective side surfaces 22. As a result, the pair of cartridges 20 move in a radial direction (Y direction) perpendicular to the axis X, in which their respective side surfaces 22 are perpendicular to the axis X.

[0027] The cartridge 20 is fixed to the tool body 10 by a bolt 28. The cartridge 20 has an oval hole 24, which is a through hole through which the bolt 28 is inserted parallel to the axis X. The oval hole 24 is a counterbore hole, and the head of the bolt 28 contacts the counterbore, allowing only the shank to be inserted. The oval hole 24 is formed so that the major axis is parallel to the extension direction of the second uneven portion 20b. The bolt 28 is inserted into the oval hole 24 and threadedly engages with the female thread 18 of the main body 14 of the tool body 10, thereby fixing the cartridge 20 to the tool body 10.

[0028] The radial (Y-direction) movement range of the cartridge 20 relative to the tool body 10 is the range within which the oblong hole 24 can move relative to the bolt 28. In other words, the movement range of the cartridge 20 relative to the tool body 10 is determined by the position of the bolt 28 (internal thread 18) on the tool body 10, the position of the oblong hole 24 on the cartridge 20, and the length of the major axis of the oblong hole 24.

[0029] The cutting blade 30 is detachably attached to one radial end of the side surface 22 of the cartridge 20 by a bolt 32. In other words, the cartridge 20 holds the cutting blade 30.

[0030] Boring is a process in which the boring head 1 rotates, causing the cutting edges of a pair of cutting blades 30 attached to a pair of cartridges 20 to cut the inner surface of an existing hole, thereby enlarging the inner diameter of the hole. As described above, the radial movement range of the cartridge 20 relative to the tool body 10 is determined by factors such as the length of the major axis of the oval hole 24, and therefore the hole diameter that can be bored by the cutting blades 30 is also determined by factors such as the length of the major axis of the oval hole 24. Hereinafter, the state of the boring head 1 when the distance between the cutting edges of the pair of cutting blades 30 is shortest, i.e., when the smallest possible hole diameter is reached, will be referred to as the "minimum diameter state" (see FIG. 6). Furthermore, the state of the boring head 1 when the distance between the cutting edges of the pair of cutting blades 30 is longest, i.e., when the largest possible hole diameter is reached, will be referred to as the "maximum diameter state" (see FIG. 7). In other words, the hole diameter that can be bored by the boring head 1 ranges from the smallest hole diameter to the largest hole diameter. In the minimum diameter state, the overlapping area of ​​the side surfaces 22 of the pair of cartridges 20 when viewed from a direction perpendicular to the side surfaces 22 is greatest, and in the maximum diameter state, the overlapping area of ​​the side surfaces 22 is least.

[0031] An engagement groove 26 is formed on the bottom surface 20a of the cartridge 20 along a direction perpendicular to the side surface 22 from the side surface 22 toward the oval hole 24. That is, the engagement groove 26 is formed in a direction perpendicular to the Y direction. In this embodiment, the engagement groove 26 is formed so as to connect the side surface 22 and the oval hole 24. The engagement groove 26 is positioned so as to overlap with the accommodation hole 16 in a plan view, regardless of whether the cartridge is in the minimum diameter state or the maximum diameter state.

[0032] [Structure of Synchronizing Member] Next, the structure of the synchronizing member 40 will be described with reference to Figures 2 to 5B. The synchronizing member 40 is a cylindrical member and is housed in the housing hole 16 of the tool body 10, as shown in Figure 4. As described above, the center of the housing hole 16 is coaxial with the axis X. Therefore, when the synchronizing member 40 is housed in the housing hole 16, the axis of the synchronizing member 40 is also coaxial with the axis X. The synchronizing member 40 includes a main body 42, a flange 44, and an engagement pin 46. For ease of explanation, the axis of the synchronizing member 40 is also designated by the symbol X in Figures 5A and 5B.

[0033] As shown in Figure 4, the main body 42 has a cylindrical shape and is housed in the housing hole 16. When the synchronizing member 40 is housed in the housing hole 16, the main body 42 has an outer peripheral surface 42a that is in sliding contact with the small diameter portion 16b of the housing hole 16 without rattling and that has an outer diameter that allows smooth rotation relative to the tool body 10. At this time, the bottom surface of the main body 42 abuts against the bottom surface of the small diameter portion 16b. The height of the main body 42 is such that when housed in the housing hole 16, it is close to, but does not come into contact with, the bottom surface 20a of the cartridge 20.

[0034] 2 to 5B , the flange 44 extends radially outward from the main body 42 at the end of the main body 42 facing the cartridge 20 with respect to the axis X. The flange 44 has a circular outer shape in a plan view. When the synchronizing member 40 is housed in the housing hole 16, the flange 44 is located in the large diameter portion 16a of the housing hole 16, but the outer peripheral surface 44a of the flange 44 is not in contact with the inner surface or bottom surface of the large diameter portion 16a and is separated therefrom.

[0035] The engagement pins 46 are a pair of cylindrical pins that protrude toward the cartridge 20 from an opposing surface 43 of the synchronization member 40, which is configured by the main body 42 and flange 44, on the side facing the cartridge 20. The pair of engagement pins 46 are arranged near the periphery of the flange 44. The pair of engagement pins 46 are arranged at positions that are point-symmetric, i.e., two-fold rotational symmetry, about the axis X, and each engagement pin 46 is arranged at a position equidistant (same radius) from the axis X. The pair of engagement pins 46 fit into and engage with a pair of engagement grooves 26 formed in each of the pair of cartridges 20.

[0036] [Adjusting the Outer Diameter of the Boring Head] Next, a method for adjusting the outer diameter of the cutting edge of the cutting blade 30 of the boring head 1 between the minimum diameter state and the maximum diameter state will be described. First, a pair of bolts 28 that secure the pair of cartridges 20 to the tool body 10 are loosened to make each of the pair of cartridges 20 movable relative to the tool body 10. Then, one of the pair of cartridges 20 (hereinafter, for convenience of explanation, also referred to as the "driven cartridge 20") is moved in the Y direction of the tool body 10 (radial direction of the axis X). As a result, the engagement groove 26 of the driven cartridge 20 (hereinafter, for convenience of explanation, also referred to as the "driven engagement groove 26") also moves in the Y direction, changing the distance between the axis X and the driven engagement groove 26. As a result, the synchronizing member 40 including the engagement pin 46 (hereinafter, for convenience of explanation, also referred to as the "drive engagement pin 46") engaged with the drive engagement groove 26 rotates around the axis X, and the drive engagement pin 46 moves within the drive engagement groove 26 along the extension direction of the drive engagement groove 26. The drive cartridge 20 is, for example, the cartridge 20 located on the upper side in Figures 6 and 7.

[0037] When the synchronizing member 40 rotates, the one of the pair of engagement pins 46 that is not the driven engagement pin 46 (hereinafter, for convenience of explanation, also referred to as the "driven engagement pin 46") also rotates around the axis X. When the driven engagement pin 46 rotates, the driven engagement pin 46 moves within the engagement groove 26 (hereinafter, for convenience of explanation, also referred to as the "driven engagement groove 26") that is engaged with the driven engagement pin 46 along the extension direction of the driven engagement groove 26.

[0038] When the driven engagement pin 46 moves in the driven engagement groove 26, the distance between the driven engagement groove 26 and the axis X changes. As a result, the driven engagement groove 26, i.e., the other cartridge 20 of the pair of cartridges 20 having the driven engagement groove 26 (hereinafter, for convenience of explanation, also referred to as the “driven cartridge 20”), moves relative to the axis X.

[0039] As described above, the second concave-convex portion 20b of the driven cartridge 20 is fitted into the first concave-convex portion 14b of the tool body 10, so the driven cartridge 20 moves in the Y direction (radial direction of the axis X). That is, when the driving cartridge 20 is moved in the Y direction, the driven cartridge 20 also moves in the Y direction via the synchronizing member 40. At this time, the moving directions of the driving cartridge 20 and the driven cartridge 20 are opposite (directions different by 180 degrees). The driven cartridge 20 is, for example, the cartridge 20 arranged on the lower side in FIGS. 6 and 7 .

[0040] As described above, when the pair of engagement pins 46 of the synchronization member 40 are accommodated in the accommodation hole 16, they are arranged at positions that are point-symmetric, i.e., two-fold rotational symmetry, about the axis X, and each engagement pin 46 is arranged at a position equidistant (same radius) from the axis X. Furthermore, since each of the pair of cartridges 20 has the same shape, the pair of engagement grooves 26 are also arranged at the same position in each cartridge 20. Therefore, when the pair of engagement pins 46 of the synchronization member 40 are engaged with the pair of engagement grooves 26, each of the pair of cartridges 20 is always arranged at a position that is point-symmetric about the axis X, regardless of the circumferential position of the engagement pins 46. Therefore, the distance from the axis X to each cutting edge of the pair of cutting blades 30 fixed to each of the pair of cartridges 20 is the same.

[0041] As described above, the boring head 1 of this embodiment is provided with a synchronizing member 40 having engagement pins 46 that engage with the engagement grooves 26 of the pair of cartridges 20. Therefore, when the driven cartridge 20 of the pair of cartridges 20 is moved a predetermined distance in the Y direction, the driven cartridge 20 moves, via the synchronizing member 40, in the direction opposite to the moving direction of the driven cartridge 20 by the same distance as the moving distance of the driven cartridge 20. As a result, the distance from the axis X to the cutting edges of the pair of cutting blades 30 fixed to each of the pair of cartridges 20 is always the same. In other words, the synchronizing member 40 rotates about the axis X to change the relative positions of the pair of engagement pins 46 with respect to the pair of engagement grooves 26, so that the pair of cartridges 20 move synchronously in opposite directions by the same distance.

[0042] Specifically, from the minimum diameter state shown in Figure 6, the driven cartridge 20 (the cartridge 20 arranged on the upper side in Figure 6) is moved to the left in Figure 6 to reach the maximum diameter state shown in Figure 7. At this time, the driven cartridge 20 (the cartridge 20 arranged on the lower side in Figure 6) also moves rightward from the state shown in Figure 6 in synchronization with the movement of the driven cartridge 20 to reach the maximum diameter state shown in Figure 7. Note that the head of the bolt 28 is not shown in Figures 6 and 7. Also, the driven cartridge 20 may be the cartridge 20 arranged on the lower side in Figures 6 and 7, and the driven cartridge 20 may be the cartridge 20 arranged on the upper side in Figures 6 and 7.

[0043] As described above, with the boring head 1 of this embodiment, when the driven cartridge 20 is moved a predetermined distance in the Y direction, the driven cartridge 20 moves a predetermined distance in the opposite direction in synchronization with the movement, without using a dedicated adjustment device such as a tool presetter. Therefore, in the boring head 1, the radial distances from the axis X (the rotational axis of the spindle when mounted on the machine tool 2) of the cutting edges of the pair of cutting blades 30 fixed to the pair of cartridges 20 can be easily made equal. Therefore, even if the distance between the cutting edges of the cutting blades 30 is adjusted using an inexpensive measuring device such as a vernier caliper or a micrometer, the desired distance (diameter) can be easily obtained, and a hole with the desired diameter can be machined.

[0044] Furthermore, in the boring head 1 of this embodiment, as described above, the pair of female threads 18 are disposed near the periphery of the large-diameter portion 16a of the receiving hole 16, and recesses 19 are formed between the inner circumferential surface of the large-diameter portion 16a and the inner circumferential surfaces of the pair of female threads 18, respectively, with no inner circumferential surface present at those locations. By forming the recesses 19 in this manner, the length along the axis X between the thin-walled inner circumferential surface of the large-diameter portion 16a and the inner circumferential surfaces of the pair of female threads 18 can be shortened, thereby increasing the outer diameter of the flange 44 of the synchronizing member 40 while preventing cracking of the thin-walled portion. As a result, the engaging pin 46 can be disposed radially outward, and the travel distance of the engaging pin 46 along the Y direction when the synchronizing member 40 is rotated about the axis X can be increased without increasing the outer diameters of the pair of cartridges 20 or the main body 14 of the tool body 10.

[0045] As described above, the main body 42 of the synchronizing member 40 accommodated in the accommodation hole 16 of the tool body 10 has an outer diameter that allows it to rotate smoothly without rattle relative to the small diameter portion 16b of the accommodation hole 16. That is, the outer surface 42a of the main body 42 and the inner surface of the small diameter portion 16b are in contact with each other, and in order for the synchronizing member 40 to rotate relative to the tool body 10, the tangential force acting on the main body 42 of the synchronizing member 40 must exceed the maximum static friction force acting between the main body 42 and the inner surface of the small diameter portion 16b. The tangential force acting on the main body 42 of the synchronizing member 40 is a component of the force acting in the Y direction to move the driven cartridge 20 in the Y direction. This will be explained in detail below.

[0046] A force acting in the Y direction on the driven cartridge 20 also acts in the Y direction on the driven engagement pin 46, which is engaged with the driven engagement groove 26 of the driven cartridge 20. Because the driven engagement pin 46 has a cylindrical shape, a component of the force acting in the Y direction on the driven engagement pin 46 acts in the tangential direction of the driven engagement pin 46, and a force positively correlated to that component acts in the tangential direction of the main body 42. If the force acting in the Y direction on the driven engagement pin 46 via the driven cartridge 20 is constant, the smaller the angle θ1 shown in FIG. 6 or the larger the angle θ2 shown in FIG. 7, the smaller the force acting in the tangential direction of the driven engagement pin 46, and as a result, the smaller the force acting in the tangential direction of the main body 42. Therefore, in order for the force acting in the tangential direction of the main body 42 to exceed the maximum static friction force and enable the pair of cartridges 20 to move in both directions in the Y direction (left and right directions in FIGS. 6 and 7), it is necessary for the angle θ1 to be equal to or greater than a predetermined angle and the angle θ2 to be equal to or smaller than a predetermined angle. The angle θ1 is an angle less than 90 degrees formed by a first imaginary line L1 that passes through the axis X and extends in the Y direction in a plan view when the driving cartridge 20 is in the minimum diameter state, and a second imaginary line L2 that connects the axis X and the center of the driving engagement pin 46. The angle θ2 is an angle greater than 90 degrees formed by the first imaginary line L1 that passes through the axis X and extends in the Y direction in a plan view, and a second imaginary line L2 that connects the axis X and the center of the driving engagement pin 46 when the driving cartridge 20 is in the maximum diameter state.

[0047] In the boring head 1 of this embodiment, the engagement pin 46 and the engagement groove 26 are arranged so that the angle θ1 is 15 degrees or more, preferably 20 degrees or more, and the angle θ2 is 165 degrees or less, preferably 160 degrees or less. As a result, when a force in the Y direction is applied to the driven cartridge 20, the synchronizer 40 can be rotated relative to the tool body 10, and the driven cartridge 20 and the driven cartridge 20 can be moved in both directions in the Y direction.

[0048] Other Embodiments (1) In the above embodiment, the engagement groove 26 is formed to connect the side surface 22 of the cartridge 20 with the oval hole 24, but this is not limited to this. The engagement groove 26 may be formed so as not to connect with either the side surface 22 or the oval hole 24, or with both. The length of the engagement groove 26 can be set arbitrarily depending on the amount of movement of the engagement pin 46 of the synchronization member 40 that moves within the engagement groove 26. In other words, the length of the engagement groove 26 can regulate the rotation angle of the synchronization member 40 in the boring head 1. In this case, the rotation angle of the synchronization member 40 may be regulated by the length of the oval hole 24 along the Y direction, rather than the length of the engagement groove 26.

[0049] (2) In the above embodiment, a pair of (two) cartridges 20 are moved synchronously by a synchronization member 40 having two engagement pins 46, but this is not limited to this. The synchronization member 40 may be configured to have three or more engagement pins 46 arranged at positions that are rotationally symmetrical by three or more times. In this case, by engaging one cartridge 20 with each engagement pin 46, three or more cartridges 20 can be moved synchronously by the same distance.

[0050] The present disclosure is applicable to boring heads.

[0051] DESCRIPTION OF SYMBOLS 1: Boring head 2: Machine tool 10: Tool body 14a: Tip surface (end surface) 16: Accommodation hole 18: Female thread 19: Recess 20: Cartridge 20a: Bottom surface 26: Engagement groove 30: Cutting edge 40: Synchronizing member 42: Body 42a: Outer circumferential surface 44: Flange 44a: Outer circumferential surface 46: Engagement pin L1: First imaginary line L2: Second imaginary line X: Axis θ1: Angle θ2: Angle

Claims

1. A boring head comprising: a tool body having an axis and mountable so that the axis is coaxial with the rotational axis of a machine tool spindle; a synchronizing member housed in the tool body so as to be coaxial with the axis and rotatable within the tool body; and a plurality of cartridges capable of holding cutting edges, the cartridges being attached to the end face of the tool body on the side where the synchronizing member is housed so as to be movable in a direction perpendicular to the axis, each of the cartridges having an engagement groove formed in a direction perpendicular to the direction of movement of the cartridge on its bottom face opposite the tool body, the synchronizing member having a plurality of cylindrical engagement pins that can be engaged with each of the engagement grooves, and the engagement pins being arranged in positions that are rotationally symmetrical with respect to the axis.

2. A boring head as described in claim 1, wherein the synchronizing member has a cylindrical main body and a flange extending radially outward from the main body, the outer circumferential surface of the main body being in sliding contact with the tool main body, the outer circumferential surface of the flange being spaced apart from the tool main body, and the engaging pin being disposed on the flange.

3. A boring head as described in claim 1 or 2, wherein the plurality of cartridges are configured to have a limited range of movement, and within the range of movement, the angle formed by a first imaginary line passing through the axis and parallel to the direction of movement of the cartridge, and a second imaginary line connecting the axis and the center of the engagement pin is between 15 degrees and 165 degrees.

4. A boring head as described in claim 1 or 2, wherein the tool body has a housing hole for housing the synchronizing member, a plurality of female threads arranged around the housing hole for fixing a plurality of the cartridges by screwing, and a plurality of recesses formed between the inner surface of the housing hole and the inner surfaces of each of the plurality of female threads.

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