JP4202151B2 - Spindle tool fixing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tool fixing device for a spindle, and more particularly to an apparatus capable of increasing a pulling force of a draw bar and transmitting it to a collet for gripping a tool.
[0002]
[Prior art]
Conventionally, many tool fixing devices for fixing a tool or a tool holder to a spindle of a machine tool are connected to a draw bar disposed at the center of the spindle and a distal end portion of the draw bar, and a base end of the tool or the tool holder. A collet that can grip the portion, and a drive means that can urge the draw bar in the direction of pulling the draw bar toward the main shaft base side and that can push the draw bar toward the main shaft tip side. When the tool is driven, the tool or tool holder is gripped by the collet while the tool or tool holder is pulled toward the spindle proximal end side to fix the tool to the spindle.
[0003]
Here, a tool fixing device provided with a force-increasing mechanism for increasing the tensile force of the draw bar and transmitting it to the collet has also been proposed. For example, in the tool fixing device described in Patent Document 1, a collet composed of a plurality of divided pieces divided in the circumferential direction and a cylindrical body that is externally fitted to the collet are provided, and inner and outer peripheral portions of the base end portion of the collet And two inclined surfaces formed on the front end side portion of the draw bar and the proximal end portion of the cylindrical body and capable of engaging with the two inclined surfaces of the collet. Is configured. When the draw bar is pulled to the main shaft proximal end side by the driving means, the pulling force of the draw bar is increased by the two sets of inclined surfaces in the engagement relation and transmitted to the collet, and the tool or tool holder is transferred to the tip of the collet. The tool or the tool holder is fixed to the main shaft by being pulled in while being gripped by.
[0004]
In addition, the some division | segmentation piece which comprises a collet is urged | biased to radial inside by the coil spring provided in the base end part of the collet, and it is comprised so that a collet can move smoothly with a draw bar. Furthermore, a separator having a plurality of collet expanding protrusions that protrude radially toward the main shaft proximal side and is radially formed is provided on the front end side of the collet, and the draw bar is moved to the main shaft front end side by a hydraulic cylinder or the like of the driving means. When pushed, the tip of the collet is pushed and expanded by the collet expanding protrusion of the separator, and the gripping state of the tool or tool holder by the collet is released.
[0005]
[Patent Document 1]
JP-A-9-76105 (page 4-7, FIG. 1-9)
[0006]
[Problems to be solved by the invention]
In the tool fixing device described in Patent Document 1, the pulling force of the draw bar is increased by the force-increasing mechanism at the base end of the collet, and the increased force is transmitted to the tip of the collet so that the tool or tool holder Is gripped. Therefore, as the gripping operation by the collet is repeated, stress is repeatedly applied to the middle part between the tip end part and the base end part of the collet. In some cases, the collet may be subject to fatigue failure. It is disadvantageous.
[0007]
Furthermore, when the draw bar is pushed to the spindle tip side to release the grip of the tool or tool holder, a plurality of divided pieces are radially inward to smoothly move the collet to the spindle tip side with respect to the cylinder. This requires a coil spring to be biased, which increases the number of parts and is disadvantageous in terms of production cost. In addition, when a large force is locally applied to the coil spring due to various factors, such as when the main shaft rotates at a high speed during machining, the coil spring may be easily broken. Furthermore, in order to expand the tip of the collet when releasing the tool or the tool holder, a separator having a complicated shape having a plurality of collet expanding protrusions provided radially is required, and the structure becomes complicated. This is also disadvantageous in terms of production cost.
[0008]
Furthermore, since the collet constitutes a part of the force-increasing mechanism located on the leading end side of the draw bar, the length of the collet inevitably increases. And, in order to ensure the strength, if the diameter in the expanded state of the collet tip that grips the tool holder is increased, in order to ensure the strength of the part that constitutes a part of the collet boosting mechanism and engages the draw bar, The diameter of the entire collet must be increased, and the tool fixing device becomes larger.
[0009]
The purpose of the present invention is to increase the drawbar's pulling force by the force-increasing mechanism so that the tool can be strongly fixed to the main shaft and to improve the durability of the collet, and the gripping state of the tool or tool holder can be improved with a simple structure. It is configured to be releasable.
[0010]
[Means for Solving the Problems]
The tool fixing device for a spindle according to claim 1 is a tool fixing device for fixing a tool or a tool holder attached to a tip portion of a spindle of a machine tool to the spindle, and a plurality of collet divisions divided in the circumferential direction. A collet made of a body and capable of gripping the base end of a tool or tool holder, a draw bar disposed in the center of the main shaft, a coupling mechanism for interlockingly connecting the draw bar and the collet, and the draw bar to the main shaft base side In a tool fixing device having a driving means capable of being biased in a pulling direction and capable of pushing the draw bar toward the main shaft tip side, the coupling mechanism is moved relative to the draw bar at the tip end side relative to the draw bar in the axial direction. An inner transmission member that is connected to the collet so as to be movable integrally with the main shaft proximal side, and is externally fitted to the inner transmission member and the leading end of the draw bar and is pulled by the draw bar. An outer transmission member capable of transmitting a force to the inner transmission member, a cylindrical body into which the collet and the outer transmission member can be fitted, and a force-increasing mechanism for increasing the tensile force of the draw bar and transmitting it to the outer transmission member It is characterized by this.
[0011]
When the tool or the tool holder for holding the tool is fixed to the main shaft by the tool fixing device, the draw bar is pulled to the main shaft base end side by the driving means while the tool or the tool holder is mounted on the front end portion of the main shaft. Then, the collet interlocked to the draw bar by the coupling mechanism is also driven to the main shaft proximal end side, and is fitted into the cylindrical body of the coupling mechanism, and the distal end of the collet moves radially inward to the proximal end of the tool or tool holder The part is gripped by the collet.
[0012]
At this time, the pulling force of the draw bar is increased by the force-increasing mechanism, and then transmitted to the collet via the outer transmission member that is externally fitted to the tip of the draw bar and the inner transmission member that is connected to the collet. Accordingly, the collet is strongly pulled toward the main shaft proximal side while holding the tool or the tool holder, and the tool or the tool holder is strongly fixed to the main shaft.
[0013]
According to a second aspect of the present invention, there is provided a tool fixing device for a spindle according to the first aspect of the invention, wherein the inner transmission member is formed as a cylindrical member that is externally fitted to a pipe member for passing a coolant. It is. The pipe member is for supplying coolant to the tool to cool the tool during machining, and the inner transmission member is externally fitted to the pipe member. A transmission member can be provided.
[0014]
According to a third aspect of the present invention, there is provided the spindle fixing tool device according to the first or second aspect, wherein the outer transmission member includes a plurality of divided transmission members divided in the circumferential direction. Accordingly, the pulling force of the draw bar can be evenly transmitted in the circumferential direction to the inner transmission member by the plurality of divided transmission members divided in the circumferential direction.
[0015]
According to a fourth aspect of the present invention, there is provided the main shaft tool fixing device according to the first to third aspects of the present invention, wherein when the draw bar is pushed toward the front end side of the main shaft, the outer transmission member is fitted into the cylindrical body. . When the draw bar is pushed to the front end side of the main shaft, the outer transmission member also moves to the front end side of the main shaft together with the draw bar, and the outer transmission member is fitted into the cylinder.
[0016]
According to a fifth aspect of the present invention, there is provided the main shaft tool fixing device according to any one of the first to fourth aspects, wherein the force-increasing mechanism is formed on the inner surface portion of the base end portion of the outer transmission member and is inclined so that the diameter decreases toward the base end side. The first inclined surface, the second inclined surface formed on the outer surface portion of the proximal end portion of the outer transmission member and inclined so as to increase in diameter toward the proximal end side, and the outer peripheral portion of the distal end side portion of the draw bar. It has a 3rd inclined surface engaged with an inclined surface, and a 4th inclined surface which is formed in the inner peripheral part of the base end part of a cylinder, and can be engaged with the said 2nd inclined surface. .
[0017]
When the draw bar is pulled toward the main shaft proximal side by the driving means, the first inclined surface of the outer transmission member is engaged with the third inclined surface of the draw bar, and the pulling force of the draw bar is increased by the first and third inclined surfaces. Then, it is transmitted from the first inclined surface to the outer transmission member as a radially outward force. Further, the second inclined surface of the outer transmission member is engaged with the fourth inclined surface of the cylindrical body, and the force transmitted from the draw bar to the first inclined surface of the outer transmission member is further increased by the second and fourth inclined surfaces. The force is increased and transmitted to the cylinder as a force in the direction of the tip of the main shaft. Therefore, the outer transmission member receives a reaction force in the main shaft proximal direction with the same magnitude as the increased force from the cylinder, and this reaction force is transmitted to the collet via the inner transmission member. The tool or tool holder is securely held by the collet and fixed to the main shaft.
[0018]
A tool fixing device for a spindle according to claim 6 is the one according to claims 1 to 5. Any In the invention, a base end portion of each collet divided body The cylindrical body at a portion facing the cylindrical body A projecting portion projecting to the side, an annular projecting portion projecting inward to the inner peripheral portion of the cylindrical body, and a plurality of projecting portions and an annular projecting portion when the collet is driven to be released to the extrusion side by the driving means. By moving the base end portions of the plurality of collet divided bodies radially inward by the contact, the front end portions of the plurality of collet divided bodies are expanded, and the plurality of collet divided bodies are released from gripping. To do.
[0019]
When the draw bar is pushed toward the main shaft tip by the driving means, and the collet is also driven to the extrusion side along with that, a protruding portion formed on the outer peripheral portion of the collet divided body is formed on the inner peripheral portion of the cylindrical body. Abuts against the annular protrusion. At this time, the base end portions of the plurality of collet divided bodies are driven radially inward by the annular projecting portion, and accordingly, the distal end portion of the collet divided body moves radially outward and expands. The gripping state of the tool or tool holder by the plurality of collet divided bodies is released.
[0020]
According to a seventh aspect of the present invention, in the invention of the third aspect, the plurality of collet divided bodies are provided with a plurality of first projecting engaging portions projecting toward the main shaft base end side, and the plurality of divided transmission members are provided with the plurality of collet divided bodies. A second projecting engagement portion projecting toward the front end of the main shaft is provided, a plurality of groove portions are formed in the circumferential direction on the inner transmission member, and a plurality of first and second projecting engagement portions are engaged with the plurality of groove portions. Thus, the plurality of collet divided bodies and the plurality of divided transmission members are configured not to move in the circumferential direction with respect to the inner transmission member.
[0021]
Accordingly, the plurality of collet divided bodies and the plurality of divided transmission members are regulated so as not to move in the circumferential direction with respect to the inner transmission member. Therefore, vibrations during high-speed rotation of the main shaft can be prevented as much as possible.
[0022]
According to a eighth aspect of the present invention, there is provided the main shaft tool fixing device according to the third aspect of the invention, wherein the inner transmission member and the outer transmission member are provided with an engagement mechanism that interlocks and connects both the inner transmission member and the inner transmission member. An annular engagement groove formed on the outer peripheral portion of the plurality of split transmission members, and a plurality of engagement portions that are respectively formed at the distal ends of the plurality of split transmission members and engage with the annular engagement groove. . Therefore, when the draw bar is pulled toward the main shaft base end by the driving means, the pulling force of the draw bar is increased by the force-increasing mechanism and then transmitted to the plurality of split transmission members. Here, since the engaging portions of the plurality of split transmission members are engaged with the annular engagement grooves of the inner transmission member, the force increased from the plurality of split transmission members is transmitted to the inner transmission member.
[0023]
According to a ninth aspect of the present invention, there is provided the tool fixing device for a main shaft according to the eighth aspect of the invention, wherein the annular engagement groove is formed such that a cross section including the axis of the draw bar is partially arcuate, and inner surfaces of the plurality of engagement portions are also formed. The cross section including the shaft center is partly formed in an arc shape so as to be engaged with the annular engagement groove. Accordingly, a plurality of engaging portions having the same cross section formed in an arc shape are engaged with a portion of the annular engagement groove including a cross section including the shaft center formed in an arc shape. Durability can be improved by reducing the surface pressure between the annular engagement grooves. Accordingly, when the draw bar is urged in the direction of pulling the main shaft proximal side by the driving means, the base end portion of the outer transmission member is smoothly moved radially outward while engaging the engaging portion and the annular engaging groove. Can be made.
[0024]
According to a tenth aspect of the present invention, there is provided a tool fixing device for a spindle according to any one of the first to ninth aspects. And a fluid pressure cylinder that pushes the draw bar toward the tip end side of the main shaft against the urging force of the urging member. Since the urging force of the elastic urging member is increased by the force-increasing mechanism and transmitted to the collet, the tool or tool holder can be firmly fixed to the main shaft even with a relatively small elastic urging member, and the elastic urging member It is also possible to reduce the size of the fluid pressure cylinder that releases the collet gripping state by pushing the draw bar toward the tip end side of the spindle against the force.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described. This embodiment is an example in which the present invention is applied to a spindle unit of a horizontal machining center. In the following description, the top, bottom, left, and right in FIG.
As shown in FIGS. 1 to 4, the spindle unit 1 can unfix the spindle 2, the housing 3 including the drive motor 12 that rotationally drives the spindle 2, and the tool holder 5 that holds the tool 5 a on the spindle 2. And a tool fixing device 4 for fixing to the tool.
[0026]
A tapered holder holding portion 2a whose diameter increases toward the distal end side is formed at the distal end portion of the main shaft 2, and a tapered shank formed at the proximal end portion of the tool holder 5 is formed on the holder holding portion 2a. The part 5b can be engaged. The main shaft 2 is disposed in the housing 3, and both end portions of the main shaft 2 are rotatably supported by the housing 3 by bearings 10 and 11. Housing the motor in the housing 3 Part Includes a drive motor 12 that rotates the main shaft 2 with respect to the housing 3.
[0027]
Inside the main shaft 2, the holder holding portion 2a described above and the accommodation hole 2b connected to the right end of the holder holding portion 2a are formed in series. The tool holder 5 includes a shank portion 5b that can be fitted into the holder holding portion 2a, a small-diameter shaft portion 5c and an engaged portion 5d that are formed at the base end portion of the shank portion 5b, and a distal end side of the shank portion 5b. And a large-diameter gripper 5e that is formed and gripped by an automatic tool changer (not shown) when the tool 5a is replaced. In a state where the tool holder 5 is mounted on the main shaft 2, the shank portion 5b is brought into close contact with the holder holding portion 2a, and the engaged portion 5d faces the front end portion of the accommodation hole 2b. And the main part of the tool fixing device 4, such as the below-mentioned draw bar 21, etc. is accommodated in the accommodation hole 2b.
[0028]
Next, the tool fixing device 4 will be described.
As shown in FIG. 1 to FIG. 7, the tool fixing device 4 includes a collet 20 including four collet divided bodies 30 divided in the circumferential direction and capable of gripping the proximal end portion of the tool holder 5, and the central portion of the main shaft 2. , A connecting mechanism 22 that interlocks and connects the draw bar 21 and the collet 20, and can draw the draw bar 21 in the direction of pulling it toward the proximal end of the main shaft 2. And a drive mechanism 23 that can be pushed sideways. Here, FIGS. 1 to 7 are cross-sectional views showing a state in which the cross section below the axis of the main shaft 2 is cut by a plane shifted by 45 degrees in the circumferential direction from the upper cross section.
[0029]
First, the collet 20 will be described.
As shown in FIGS. 6-8, the collet 20 is arrange | positioned in the accommodation hole 2b in the right side of the holder holding | maintenance part 2a. As shown in FIG. 8A, the four collet segments 30 of the collet 20 are arranged side by side in the circumferential direction, and each collet segment 30 is formed in a substantially arc shape in a side view. Since these four collet segments 30 have the same configuration, one of them will be described below.
[0030]
As shown in FIG. 8, the tip of the collet split body 30 has a gripping portion 30 a that projects radially inward and engages with an engaged portion 5 d at the base end of the tool holder 5 to grip the tool holder 5. A protruding portion 30b that protrudes radially outward is formed at a position immediately to the right of the grip portion 30a. A stepped portion 30 c that engages with an annular protrusion 45 of an inner transmission member 40 of the coupling mechanism 22 described later is formed in an inner portion of the middle portion in the left-right direction of the collet divided body 30. An inclined surface 30d is formed on the inner peripheral portion so as to incline toward the diameter enlargement side toward the right. Further, as shown in FIGS. 6 and 7, the right end of the collet divided body 30 A portion of the (base end) that faces a first cylinder 55 described later includes a first cylinder 55. A steel ball 31 (corresponding to a protruding portion) that partially protrudes to the side is mounted.
[0031]
Further, each collet divided body 30 is formed with a projecting engagement portion 30e (first projecting engagement portion) projecting from the base end to the right (main shaft base end side), as shown in FIG. As shown, the four projecting engagement portions 30e of the four collet divided bodies 30 are respectively provided at positions shifted by 90 degrees in the circumferential direction. As shown in FIGS. 5 to 7, these four projecting engagement portions 30 e are respectively engaged with four groove portions 46 a formed in the inner transmission member 40 of the coupling mechanism 22 described later, and divided into four collets. The body 30 is regulated so as not to move in the circumferential direction with respect to the inner transmission member 40.
[0032]
Next, the draw bar 21 will be described.
As shown in FIGS. 1 to 7, the distal end portion of the draw bar 21 is slidably fitted into a cylindrical member 32 mounted in the accommodation hole 2 b, and is further formed at the proximal end portion of the draw bar 21. An annular spring receiving portion 21a is slidably fitted in the receiving hole 2b, and the draw bar 21 is disposed in the receiving hole 2b so as to be movable relative to the main shaft 2 in the left-right direction. The leading end of the draw bar 21 is formed with a housing recess 21b that partially houses an inner transmission member 40 described later and a spring housing hole 21c that communicates with the right end of the housing recess 21b. A first inclined surface of an outer transmission member 41 to be described later is disposed on the outer peripheral portion of the right side portion of the draw bar 21 at a position slightly to the right of the housing recess 21b. 60 A third inclined surface 62 is formed to engage with the. A tube member 33 for allowing the coolant to pass is disposed at the distal end side of the draw bar 21, and the tube member 33 is moved to the left so that the tube member 33 contacts the proximal end of the tool holder 5 in the spring accommodation hole 21 c. A biasing coil spring 34 is disposed.
[0033]
Next, the connection mechanism 22 will be described.
The coupling mechanism 22 is disposed on the distal end side of the draw bar 21 so as to be movable relative to the draw bar 21 in the axial direction, and is coupled to the collet 20 so as to be movable integrally to the right (the base end side of the main shaft 2). The inner transmission member 40, the outer transmission member 41 that is externally fitted to the inner transmission member 40 and the tip of the draw bar 21 and that can transmit the tensile force of the draw bar 21 to the inner transmission member 40, and the inner transmission member 40 and the outer transmission. An engagement mechanism 42 for interlockingly connecting the members 41, a cylindrical body 43 into which the collet 20 and the outer transmission member 41 can be fitted, and a force-increasing mechanism 44 for increasing the tensile force of the draw bar 21 and transmitting it to the outer transmission member 41. I have.
[0034]
As shown in FIGS. 6, 7, and 9, the inner transmission member 40 is formed in a cylindrical member that is fitted on the pipe member 33 for allowing the coolant to pass through. Is slidably fitted in a housing recess 21 b formed at the tip of the draw bar 21. As shown in FIG. 9, the inner transmission member 40 is formed with three annular projecting portions 45, 46, 47 projecting radially outward at intervals. The leftmost annular protrusion 45 is engageable with the stepped portions 30 c of the four collet divided bodies 30.
[0035]
As shown in FIG. 9 (b), eight groove portions 46a and 46b are formed on the outer peripheral portion of the annular projecting portion 46 located in the middle at a position equally divided in the circumferential direction. Of the eight groove portions 46a and 46b, the four groove portions 46a formed at four positions on the upper, lower, left and right sides of the annular protrusion 46 in FIG. Each is engaged. On the other hand, the projecting engagement portions 50a of the four split transmission members 50 of the outer transmission member 41 (described later) are respectively associated with the four groove portions 46b formed at positions shifted by 45 degrees in the circumferential direction from the four groove portions 46a. Match. Between the two annular protrusions 46 and 47, an annular engagement groove 40a, which will be described later, is also formed on the outer peripheral portion of the inner transmission member 40.
[0036]
As shown in FIGS. 6, 7, and 10, the outer transmission member 41 includes four divided transmission members 50 that are divided in the circumferential direction. 50 The outer transmission member 41 is fitted on the inner transmission member 40 and the draw bar 21 in a state where the outer transmission member 41 is disposed at a position shifted by 45 degrees in the circumferential direction with respect to the four collet divided bodies 30.
[0037]
As shown in FIG. 10, each split transmission member 50 is formed with a projecting engagement portion 50a (second projecting engagement portion) that projects leftward from the front end (the front end side of the main shaft). As shown in FIG. 4, the four projecting engagement portions 50a of the four split transmission members 50 are provided at positions shifted by 90 degrees in the circumferential direction. As shown in FIGS. 5 to 7, these four protruding engaging portions 50 a engage with the four groove portions 46 b of the inner transmission member 40, respectively, and the four divided transmission members 50 are connected to the inner transmission member 40. On the other hand, it is regulated not to move in the circumferential direction.
[0038]
An engagement portion 50b that engages with the annular engagement groove 40a of the inner transmission member 40 is formed at the distal end portion of the split transmission member 50 so as to protrude radially inward. An engaging member 51 that engages in close contact with an inner surface portion of a cylinder 43 to be described later is attached to the outer surface portion.
[0039]
An inclined surface forming portion 50 c that protrudes radially outward and radially inward is provided at the right end of the split transmission member 50. Four in the outer transmission member 41 The left side portion of the inner surface portion of the inclined surface forming portion 50c is inclined so as to decrease in diameter toward the right side (base end side). Annular A first inclined surface 60 is formed; The four The left side portion of the outer surface portion of the inclined surface forming portion 50c is inclined so as to increase in diameter toward the right side. Annular A second inclined surface 61 is formed.
[0040]
The engagement mechanism 42 includes an annular engagement groove 40a formed on the outer peripheral portion of the inner transmission member 40, and four engagements formed on the distal ends of the four divided transmission members 50 and engaged with the annular engagement groove 40a. Part 50b. As shown in FIG. 9A, the annular engagement groove 40 a is partially formed in an arc shape in cross section including the axis of the draw bar 21. On the other hand, as shown in FIG. 10B, the inner surface portion of the engaging portion 50b is also formed so that the cross section including the shaft center is partially formed in an arc shape and engages with the annular engaging groove 40a. Yes. Since the inner transmission member 40 and the outer transmission member 41 are interlocked and connected by the engagement mechanism 42, when the draw bar 21 is pulled toward the proximal end side of the main shaft 2 by the drive mechanism 23 described later, the draw bar 21 is pulled. The force is transmitted from the outer transmission member 41 to the inner transmission member 40, and the inner transmission member 40 and the outer transmission member 41 move integrally to the right.
[0041]
As shown in FIGS. 6 and 7, the cylindrical body 43 includes a first cylindrical body 55 and a second cylindrical body 56 that are fitted in the accommodation hole 2 b. The distal end portion of the first cylindrical body 55 engages with a stepped portion 2c formed at the distal end portion of the accommodation hole 2b, and the proximal end surface of the second cylindrical body 56 is in contact with the distal end surface of the cylindrical member 32. The body 43 is disposed in the accommodation hole 2 b so as not to move relative to the main shaft 2.
[0042]
An annular projecting portion 55 a that projects inward is integrally provided on the inner peripheral portion of the proximal end portion of the first cylindrical body 55. When the draw bar 21 is pushed to the tip side by the drive mechanism 23 described later and the collet 20 is pushed to the left, the four steel balls 31 provided on the four collet divided bodies 30 come into contact with the annular projecting portion 55a. . Here, as described above, an inclined surface 30 d that is inclined toward the diameter-enlarging side toward the right is formed on the inner peripheral portion of the right half of the collet divided body 30, so that the base end portion of the collet divided body 30 is formed. And a gap exists between the inner transmission member 40 and the inner transmission member 40. Therefore, as shown in FIG. 2, when the four steel balls 31 come into contact with the annular protrusion 55 a, the base end portions of the four collet divided bodies 30 move radially inward and the distal ends of the collet divided bodies 30 The part protrudes leftward from the first cylinder 55, the gripping part 30a moves radially outward, and the gripping state of the tool holder 5 by the collet 20 is released.
[0043]
A fourth inclined surface 63 that can be engaged with the second inclined surface 61 formed on the outer transmission member 41 is formed on the inner peripheral portion of the base end portion of the second cylindrical body 56. In addition, a concave portion 32 a is formed at the distal end portion of the cylindrical member 32, and when the draw bar 21 is pulled toward the proximal end side of the main shaft 2 by the drive mechanism 23, the inclined surface forming portion 50 c of the outer transmission member 41 is formed. It can move radially outward.
[0044]
As shown in FIGS. 6, 7, and 11, the force-increasing mechanism 44 includes a first inclined surface 60 formed on the inner surface portion of the proximal end portion of the outer transmission member 41 and an outer surface of the proximal end portion of the outer transmission member 41. A second inclined surface 61 formed on the outer peripheral portion, a third inclined surface 62 formed on the outer peripheral portion of the distal end portion of the draw bar 21 and engaged with the first inclined surface 60, and an inner periphery of the proximal end portion of the cylindrical body 43 And a fourth inclined surface 63 that can be engaged with the second inclined surface 61.
[0045]
In the state where the inclined surface forming portion 50c of the outer transmission member 41 is located on the left side (front side) of the fourth inclined surface 63, When the draw bar 21 is pulled rightward by the drive mechanism 23, the first inclined surface 60 of the outer transmission member 41 is engaged with the third inclined surface 62 of the draw bar 21. Moves to the right together with the draw bar 21. However, as shown in FIG. 6, when the inclined surface forming portion 50c of the outer transmission member 41 jumps out of the cylindrical body 43 to the right side, the inclined surface forming portion 50c moves radially outward in the space formed inside the recess 32a. As the draw bar 21 moves to the right relative to the outer transmission member 41, the four divided transmission members 50 are rotated by the third inclined surface 62, and the inclined surface forming portions thereof. 50c is moved radially outward.
[0046]
As shown in FIG. 7, when the inclined surface forming portion 50 c moves radially outward and the second inclined surface 61 of the inclined surface forming portion 50 c engages with the fourth inclined surface 63 of the cylindrical body 43, A tensile force is transmitted to the collet 20 via the outer transmission member 41 and the inner transmission member 40. At this time, due to the engagement relationship between the first inclined surface 60 and the third inclined surface 62 and the engagement relationship between the second inclined surface 61 and the fourth inclined surface 63, the pulling force of the draw bar 21 is increased and the collet 20 Communicated.
[0047]
That is, as shown in FIG. 11, the tensile force of the draw bar 21 transmitted from the third inclined surface 62 of the draw bar 21 to the first inclined surface 60 of the outer transmission member 41 is F. ₀ , N on the third inclined surface 62 ₀ When the inclination angle of the first inclined surface 60 and the third inclined surface 62 is θ, and the friction coefficient between the first inclined surface 60 and the third inclined surface 62 is μ, the inclined surface forming portion 50c is radially outward. Pushing force F ₁ F ₁ = N ₀ cos θ-μN ₀ sin θ. Where N ₀ = F ₀ / Sin θ.
[0048]
And this F ₁ Acts on the fourth inclined surface 63 of the cylindrical body 43 from the second inclined surface 61 of the outer transmission member 41. A force F acting on the cylinder 43 in the horizontal direction when the vertical effect on the fourth inclined surface 63 is N1, and the inclination angle of the second inclined surface 61 and the fourth inclined surface 63 is φ. ₂ F ₂ = N ₁ cosφ-μN ₁ sinφ. Where N ₁ = F ₁ / Sinφ. This F ₂ A rightward force having the same magnitude as that acts on the outer transmission member 41 as a reaction force from the cylindrical body 43 and pulls the collet 20 into the cylindrical body 43 via the inner transmission member 40.
[0049]
For example, if θ = φ = 28 ° and μ = 0.15, then F ₂ = 2.995F ₀ It becomes. Accordingly, since the pulling force of the draw bar 21 is increased and approximately three times as much force acts on the collet 20, the tool holder 5 gripped by the collet 20 is firmly attracted to the holder holding portion 2a, and the tool holder 5 is attached. Can be fixed.
[0050]
Next, the drive mechanism 23 will be described.
As shown in FIGS. 1 to 4, the drive mechanism 23 resists the biasing force of the coil spring 70 (elastic biasing member) that biases the draw bar 21 in the direction of pulling the draw bar 21 toward the proximal end of the main shaft 2. And a hydraulic cylinder 71 that pushes the draw bar 21 toward the distal end side of the main shaft 2. The coil spring 70 is fitted on the middle portion of the draw bar 21 in the left-right direction, and is disposed between the cylindrical member 32 and the spring receiving portion 21a in the accommodation hole 2b. The hydraulic cylinder 71 is connected to the base end portion of the draw bar 21 so as to be able to push the draw bar 21 leftward. Since the hydraulic cylinder 71 has a general configuration, a detailed description thereof is omitted.
[0051]
Next, the operation of the tool fixing device 4 will be described.
When fixing the tool holder 5 holding the tool 5a to the holder holding portion 2a, as shown in FIG. 2, with the tool holder 5 attached to the holder holding portion 2a, the hydraulic pressure from the hydraulic cylinder 71 of the drive mechanism 23 is increased. And the draw bar 21 is pulled rightward by the urging force of the coil spring 70. Then, as shown in FIGS. 3 and 6, the tensile force of the draw bar 21 is transmitted from the third inclined surface 62 to the outer transmission member 41. Further, since the outer transmission member 41 is interlocked and connected to the inner transmission member 40 by the engagement mechanism 42, the tensile force of the draw bar 21 is transmitted to the inner transmission member 40 and the collet 20 connected to the inner transmission member 40. Four collet segments 30 move to the right.
[0052]
At this time, the gripping portions 30a of the four collet divided bodies 30 are respectively drawn into the cylindrical body 43, and these four gripping portions 30a move radially inward to be engaged with the engaged portions 5d of the tool holder 5, respectively. In addition, the base end portion of the tool holder 5 is gripped by these four grip portions 30a.
Further, when the draw bar 21 is pulled rightward by the drive mechanism 23, the inclined surface forming portion 50c of the outer transmission member 41 moves to the outside of the cylindrical body 43 and is formed inside the recess 32a, as shown in FIG. Since the inclined surface forming portion 50c can move radially outward in the created space, the four inclined transmissions are performed by the third inclined surface 62 while the draw bar 21 moves to the right relative to the outer transmission member 41. The members 50 are rotated to move the inclined surface forming portions 50c outward in the radial direction. At this time, in the engagement mechanism 42, the annular engagement groove 40 a of the inner transmission member 40 is partially formed in an arc shape in cross section including the axis of the draw bar 21, and the four engagement portions 50 b of the divided transmission member 50 are formed. Since the inner surface part of the cross section including the axis is also formed in an arc shape, the inclined surface forming portions 50c of the four split transmission members 50 in a state where the engaging portion 50b and the annular engaging groove 40a are engaged. Is easy to move radially outward.
[0053]
When the inclined surface forming portion 50c moves radially outward, the second inclined surface 61 of the inclined surface forming portion 50c engages with the fourth inclined surface 63 of the cylindrical body 43, and the tensile force of the draw bar 21 is increased by the outer transmission member 41. And, it is transmitted to the collet 20 via the inner transmission member 40. At this time, in the force-increasing mechanism 44, the first inclined surface 60 and the third inclined surface 62 are engaged, and the second inclined surface 61 and the fourth inclined surface 63 are engaged, whereby the pulling force of the draw bar 21 is increased. Is increased and transmitted to the collet 20, the tool holder 5 gripped by the collet 20 can be firmly pulled into the holder holding portion 2a and fixed.
[0054]
When releasing the fixation of the tool holder 5, the hydraulic pressure is supplied to the hydraulic cylinder 71 of the drive mechanism 23 to push the draw bar 21 to the left against the urging force of the coil spring 70. Then, as shown in FIG. 6, the draw bar 21 moves to the left relative to the outer transmission member 41, the tip of the draw bar 21 comes into contact with the annular protrusion 47 of the inner transmission member 40, and the inner transmission member 40 and collet 20 also move to the left. At this time, the inclined surface forming portion 50 c of the outer transmission member 41 moves inward in the radial direction, and the outer transmission member 41 moves to the left integrally with the inner transmission member 40 and is fitted into the cylinder 43. Then, the four collet divided bodies 30 move to the left, the tip portions of these collet divided bodies 30 jump out from the first cylindrical body 55 to the left, and the four steel balls 31 provided on the four collet divided bodies 30. Comes into contact with the annular projecting portion 55a of the first cylinder 55, the base end portions of the four collet divided bodies 30 move radially inward and the gripping portion 30a moves radially outward to move the tool holder by the collet 20 5 is released.
[0055]
According to the tool fixing device 4 described above, the following effects can be obtained.
1) Since the pulling force by the drive mechanism 23 acting on the draw bar 21 is increased by the force-increasing mechanism 44 and then transmitted to the collet 20 through the two members of the outer transmission member 41 and the inner transmission member 40, the tool holder When fixing 5 or releasing the fixing, an excessive force does not act on these two members, and fatigue failure does not easily occur, so that the durability is excellent.
[0056]
Further, by separately configuring the collet 20 and the force-increasing mechanism 44 (outer transmission member 41), the collet does not become unnecessarily long like the collet described in Patent Document 1, and the collet 20 and the outer transmission member 41 are not required. Can be set to an appropriate length. Furthermore, since the diameter of the grip portion 30a of the collet 20 that grips the tool holder 5 and the diameter of the outer transmission member 41 that is fitted on the tip of the draw bar 21 can be set to appropriate sizes, respectively. The tool fixing device 4 can be downsized while ensuring the strength of the collet 20 and the outer transmission member 41.
[0057]
2) Since the inner transmission member 40 is formed as a cylindrical member that is externally fitted to the pipe member 33 for allowing the coolant to pass therethrough, the inner transmission member 40 is disposed by effectively using the space in the main shaft 2. Therefore, the main shaft 2 can be reduced in size.
[0058]
3) Since the outer transmission member 41 includes the four divided transmission members 50 divided in the circumferential direction, when the draw bar 21 is pulled toward the proximal end side of the main shaft 2 by the drive mechanism 23, the tensile force of the draw bar 21 is increased. The collet 20 can be evenly transmitted in the circumferential direction.
[0059]
4) The force-increasing mechanism 44 includes first and second inclined surfaces 60 and 61 formed on the outer transmission member 41, and a third inclined surface 62 that is formed on the tip side portion of the draw bar 21 and engages with the first inclined surface 60. And a fourth inclined surface 63 formed at the proximal end portion of the cylindrical body 43 and engageable with the second inclined surface 61, and when the draw bar 21 is pulled toward the proximal end side of the main shaft 2 by the drive mechanism 23, Since the first inclined surface 60 and the third inclined surface 62 are engaged, and the second inclined surface 61 and the fourth inclined surface 63 are engaged, the tensile force of the draw bar 21 can be increased. The structure of the booster mechanism 44 can be simplified.
[0060]
5) When the drive mechanism 23 releases the collet 20 to the extruding side, four steel balls 31 attached to the four collet divided bodies 30 and an annular protrusion 55a formed on the inner peripheral portion of the cylindrical body 43, , The base end portions of the four collet divided bodies 30 are moved inward in the radial direction to release the grip of the four collet divided bodies 30, so that the tool holder 5 of the collet 20 with a very simple structure can be used. The grip state can be released.
[0061]
6) In the engagement mechanism 42, the annular engagement groove 40a of the inner transmission member 40 is partially formed in an arc shape in cross section including the axis of the draw bar 21, and the outer transmission member 41 engaged with the annular engagement groove 40a. The four engaging portions 50b are also partially formed in an arc shape in cross section including the shaft center. Therefore, when the draw bar 21 is pulled toward the base end side of the main shaft 2 by the drive mechanism 23, the engaging portions 50b The inclined surface forming portion 50c of the outer transmission member 41 can be smoothly moved radially outward while the 50b and the annular engagement groove 40a are engaged.
[0062]
7) Four projecting engaging portions 30e formed on the four collet divided bodies 30 and four projecting engaging portions 50a formed on the four divided transmitting members 50 of the outer transmitting member 41 are respectively connected to the inner transmitting member. Since the four collet split bodies 30 and the four split transmission members 50 are restricted so as not to move in the circumferential direction with respect to the inner transmission member 40, these are engaged with the groove portions 46 a and 46 b formed in 40. The four collet divided bodies 30 and the four divided transmission members 50 are arranged at positions symmetrical with respect to the axis of the main shaft 2, so that vibration during the high-speed rotation of the main shaft 2 can be prevented as much as possible. Furthermore, since the pulling force of the draw bar 21 is evenly transmitted in the circumferential direction to the tool holder 5 via the outer transmission member 41, the inner transmission member 40, and the collet 20, the tool holder 5 is securely attached to the holder holding portion 2a. Can be fixed.
[0063]
Next, modified embodiments in which various modifications are made to the embodiment will be described. However, the same components as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof is omitted as appropriate.
1] The number of divisions of the plurality of collet divided bodies 30 of the collet 20 and the plurality of divided transmission members 50 of the outer transmission member 41 is not limited to four, such as the diameter of the main shaft 2 and the strength of the tensile force of the draw bar 21. You may change suitably according to various conditions.
2] Instead of the steel balls 31 provided on the collet divided body 30, a protruding portion that protrudes radially outward is provided integrally with the collet divided body 30, and the protruding portion is formed on the annular protruding portion 55a of the cylindrical body 43. You may comprise so that it may contact | abut and the holding | grip cancellation | release of the several collet division body 30 may be carried out.
[0064]
3] In the above embodiment, the tool holder 5 holding the tool 5a is gripped by the collet 20 and the tool 5a is fixed to the spindle 2. However, the tool 5a is directly gripped by the collet 20. May be.
4] In the above-described embodiment, the cylindrical body 43 is composed of the two members of the first cylindrical body 55 and the second cylindrical body 56. However, the first cylindrical body 55 and the second cylindrical body 56 are integrated with each other. You may form and a cylindrical body may be comprised by one member.
[0065]
【The invention's effect】
According to the first aspect of the present invention, the pulling force of the draw bar is increased by the force-increasing mechanism and transmitted to the outer transmission member, and further transmitted from the outer transmission member to the collet via the inner transmission member. When the holder is fixed or released, an excessive force does not act on these two members that transmit a force to the collet, and fatigue failure is not likely to occur. Therefore, the durability is excellent.
[0066]
Further, by configuring the collet and the force-increasing mechanism (outer transmission member) separately, the collet does not become unnecessarily long like the collet described in Patent Document 1, and the collet and the outer transmission member have an appropriate length. Can be set. Furthermore, since the diameter of the collet that holds the tool or the tool holder and the diameter of the outer transmission member that is fitted around the tip of the draw bar can be set to appropriate sizes, respectively, the collet and the outer transmission member It is also possible to reduce the size of the tool fixing device while ensuring the strength.
[0067]
Furthermore, by separately configuring the collet and the force-increasing mechanism (outer transmission member), the tool fixing device can be used to attach and detach the tool or tool holder, drive the draw bar, and grasp and release the tool or tool holder using the collet. It becomes easy to set the various operation timings in an optimal combination, and the cycle time of the whole machining can be shortened.
[0068]
According to the second aspect of the present invention, since the inner transmission member is formed on the cylindrical member that is externally fitted to the pipe member for allowing the coolant to pass therethrough, the inner transmission member is effectively used by utilizing the space in the main shaft. The main shaft can be reduced in size.
[0069]
According to the invention of claim 3, since the outer transmission member is composed of a plurality of divided transmission members divided in the circumferential direction, when the draw bar is urged in the direction of pulling the main shaft proximal side by the drive mechanism, the plurality of outer transmission members are arranged. The tensile force of the draw bar can be evenly transmitted to the collet in the circumferential direction via the split transmission member.
[0070]
According to the invention of claim 4, when the draw bar is pushed toward the main shaft tip side, the outer transmission member can be moved to the main shaft front end side together with the draw bar so that the outer transmission member can be fitted inside the cylinder.
[0071]
According to the invention of claim 5, the force-increasing mechanism includes first and second inclined surfaces formed on the outer transmission member, and a third inclined surface that is formed on the tip side portion of the draw bar and engages with the first inclined surface. And a fourth inclined surface that is formed at the base end portion of the cylindrical body and engageable with the second inclined surface, engages the first inclined surface and the third inclined surface, and the second inclined surface and the second inclined surface. By engaging the four inclined surfaces, it is possible to increase the pulling force of the draw bar when the tool is fixed, so that the structure of the force-increasing mechanism can be simplified.
[0072]
According to the invention of claim 6, when the collet is driven to be released to the extrusion side by the driving means, the plurality of projecting portions of the plurality of collet divided bodies and the annular projecting portion formed on the inner peripheral portion of the cylindrical body, The By abutting, the base end portions of the plurality of collet divided bodies can be moved radially inward to expand the plurality of collet divided bodies and release the plurality of collet divided bodies. It is possible to release the collet gripping state with a simple structure.
[0073]
According to the seventh aspect of the present invention, the plurality of first projecting engagement portions of the plurality of collet split bodies and the plurality of second projecting engagement portions of the plurality of split transmission members are provided in the plurality of groove portions of the inner transmission member. Since the plurality of collet divided bodies and the plurality of divided transmission members are regulated so as not to move in the circumferential direction with respect to the inner transmission member, the plurality of collet divided bodies and the plurality of divided transmission members are It will be arrange | positioned in the symmetrical position with respect to an axial center, and the vibration at the time of the high speed rotation of a main axis | shaft can be prevented as much as possible.
[0074]
According to the eighth aspect of the present invention, the engagement mechanisms provided in the inner transmission member and the outer transmission member are respectively formed in the annular engagement groove formed in the outer peripheral portion of the inner transmission member and the distal end portions of the plurality of divided transmission members. A plurality of engagement portions that are formed and engage with the annular engagement groove, and the plurality of engagement portions engage with the annular engagement groove to interlock the inner transmission member and the outer transmission member. Therefore, when pulling the draw bar to the main shaft base end side by the driving means, the inner transmission member and the outer transmission member are moved integrally to the main shaft base end side to reliably transmit the draw bar's tensile force to the collet. Alternatively, the tool holder can be fixed firmly.
[0075]
According to the ninth aspect of the present invention, the annular engagement portion of the inner transmission member is formed such that a cross section including the axis of the draw bar is partially arcuate, and the plurality of engagements of the outer transmission member engaged with the annular engagement portion. Since the cross-section including the shaft center is also partially arc-shaped at the joint portion, the outer transmission member is smoothly moved relative to the inner transmission member in a state where the engagement portion is engaged with the annular engagement groove. It becomes possible.
[0076]
According to the invention of claim 10, since the urging force of the elastic urging member is increased by the force-increasing mechanism and transmitted to the collet, the tool or the tool holder can be firmly fixed to the main shaft even with a relatively small elastic urging member. In addition, it is possible to reduce the size of the fluid pressure cylinder that releases the collet gripping state by pushing the draw bar toward the spindle tip side against the biasing force of the elastic biasing member.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a spindle unit according to an embodiment of the present invention.
FIG. 2 is a longitudinal sectional view of a main part of a spindle unit (fixed release state).
FIG. 3 is a longitudinal sectional view of a main part of a spindle unit (during a fixing operation).
FIG. 4 is a longitudinal sectional view of a main part of a spindle unit (fixed state).
FIG. 5 is a perspective view of a main part of the tool fixing device.
6 is a partially enlarged view of FIG. 3;
7 is a partially enlarged view of FIG. 4;
8A and 8B are views showing a collet, where FIG. 8A is a right side view, and FIG. 8B is a cross-sectional view taken along line AA in FIG.
9A and 9B are diagrams showing an inner transmission member, in which FIG. 9A is a longitudinal sectional view, and FIG. 9B is a sectional view taken along line BB of FIG.
10A and 10B are diagrams showing the outer transmission member, where FIG. 10A is a left side view, and FIG. 10B is a cross-sectional view taken along the line CC of FIG.
FIG. 11 is an explanatory diagram for explaining the operation of the force-increasing mechanism.
[Explanation of symbols]
2 Spindle
4 Tool fixing device
5a Tool
5 Tool holder
20 Collet
21 Drawbar
22 Linking mechanism
23 Drive mechanism
30 Collet division
30e Protruding engagement part
31 steel balls
33 Pipe members
40 Inner transmission member
40a Annular engagement groove
41 Outer transmission member
42 Engagement mechanism
43 cylinder
44 Booster mechanism
46a, 46b groove
50 Split transmission member
50a Protruding engagement part
50b engagement part
55a Annular protrusion
60 First inclined surface
61 Second inclined surface
62 3rd inclined surface
63 4th inclined surface
70 Coil spring
71 Hydraulic cylinder

Claims (10)

A tool fixing device for fixing a tool or a tool holder mounted on a distal end portion of a main spindle of a machine tool to the main spindle, and comprising a plurality of collet division bodies divided in the circumferential direction and gripping a base end portion of the tool or the tool holder Possible collet, drawbar arranged in the center of the main shaft, a coupling mechanism that interlocks and connects the drawbar and collet, and the drawbar can be biased in the direction of pulling the main shaft to the main shaft, and the drawbar is at the front end of the main shaft In a tool fixing device comprising a drive means that can be pushed to the right,
The coupling mechanism is
An inner transmission member disposed on the distal end side of the draw bar so as to be movable relative to the draw bar in an axial direction and connected to a collet so as to be integrally movable toward the main shaft base end side;
An outer transmission member that is externally fitted to the inner transmission member and the tip of the draw bar and that can transmit the draw bar's tensile force to the inner transmission member;
A cylindrical body in which the collet and the outer transmission member can be fitted;
A force-increasing mechanism that increases the pulling force of the draw bar and transmits it to the outer transmission member;
A tool fixing device for a spindle, comprising:   The main shaft tool fixing device according to claim 1, wherein the inner transmission member is formed in a cylindrical member that is externally fitted to a pipe member for allowing a coolant to pass therethrough.   The main shaft tool fixing device according to claim 1, wherein the outer transmission member includes a plurality of divided transmission members divided in a circumferential direction.   The main shaft tool fixing device according to any one of claims 1 to 3, wherein when the draw bar is pushed toward the front end of the main shaft, the outer transmission member is fitted into the cylinder.   The force-increasing mechanism is formed on an inner surface portion of the base end portion of the outer transmission member and is inclined on the base end side so as to be reduced in diameter, and on the outer surface portion of the base end portion of the outer transmission member. A second inclined surface that is inclined to increase in diameter toward the side, a third inclined surface that is formed on the outer peripheral portion of the tip side portion of the draw bar and engages with the first inclined surface, and an inner end of the cylindrical body The tool fixing device for a spindle according to any one of claims 1 to 4, further comprising a fourth inclined surface formed on a peripheral portion and engageable with the second inclined surface. Said protrusion protruding into the cylindrical body side portion facing the tubular body of the base end portion of the collet divided body is provided, an annular protrusion protruding inward at the inner circumferential portion of the cylindrical body,
When the collet is driven to be released to the extrusion side by the driving means, a plurality of collet divisions are performed by moving the base end portions of the plurality of collet divided bodies radially inward by contact of the plurality of protrusions and the annular protrusions. The spindle tool fixing device according to any one of claims 1 to 5, wherein a tip end portion of the body is expanded to release gripping of the plurality of collet divided bodies.   The plurality of collet divided bodies are provided with a plurality of first projecting engagement portions projecting toward the main shaft base end side, and the plurality of split transmission members are provided with second projecting engagement portions projecting toward the front end of the main shaft, A plurality of groove portions are formed in the inner transmission member in the circumferential direction, and a plurality of first and second projecting engagement portions are engaged with the plurality of groove portions, so that the plurality of collet divided bodies and the plurality of division transmission members transmit the inside. 4. The spindle tool fixing device according to claim 3, wherein the spindle tool fixing device is configured not to move in a circumferential direction with respect to the member. The inner transmission member and the outer transmission member are provided with an engagement mechanism that interlocks and connects these two members,
The engagement mechanism includes an annular engagement groove formed on the outer peripheral portion of the inner transmission member, and a plurality of engagement portions that are formed at the distal ends of the plurality of divided transmission members and engage with the annular engagement groove. The tool fixing device for a spindle according to claim 3, comprising:   The annular engagement groove has a partially arc-shaped cross section including the axis of the draw bar, and the inner surfaces of the plurality of engaging portions also have a partially arc-shaped cross section including the axis. 9. The spindle tool fixing device according to claim 8, wherein the tool fixing device is configured to engage with a mating groove.   The driving means includes an elastic urging member that urges the draw bar in a direction of pulling the draw bar toward the main shaft base side, and a fluid pressure cylinder that pushes the draw bar toward the main shaft tip side against the urging force of the elastic urging member. The spindle tool fixing device according to any one of claims 1 to 9, further comprising:

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