JP2002337082A - Material clamping device and automatic lathe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remarkably improve acting efficiency of a chuck while reducing the dimension of a total unit as small as possible, in a material clamping device which can easily automatically adjust clamping force of the chuck. SOLUTION: This material clamping device 10 comprises a chuck 14 concentrically installed in an inner side tip end region of an axial line directional through hole 12a of a spindle 12, an operating mechanism 16 operating a clamp part opened/closed of the chuck 14 to make it fixedly clamp a bar material, and a drive part 18 driving the operating mechanism 16. A linear motor 54 is mounted in the drive part 18. The linear motor 54, transmitting its thrust to the operating mechanism 16 through a thrust transmitter 62, moves an operating member 40 in an axial line direction of the spindle 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material holding device that can be equipped on a machine tool. Further, the present invention relates to an automatic lathe provided with a material holding device.

[0002]

2. Description of the Related Art In a machine tool, a chuck having a gripper that can be opened and closed, a mechanism for opening and closing the gripper of the chuck, and an operating mechanism for fixedly holding a workpiece during a machining process. There is known a device equipped with a material gripping device having a driving unit for driving the material. For example, N
2. Description of the Related Art In a machine tool capable of performing automatic turning such as a C lathe (generally referred to as an automatic lathe in this specification), a chuck (generally referred to as an automatic lathe) having a hollow cylindrical main body formed with an elastically deformable slit-shaped gripping portion. A material gripping device is known in which a collet chuck is installed concentrically in the inner front end region of a hollow main shaft, and an operating mechanism that operates to elastically deform the gripping portion of the chuck is provided alongside the main shaft. . According to this configuration, the rod-shaped workpiece to be fed in the axial direction from the rear of the main shaft to the inside of the main shaft is fixedly held on the main shaft via the chuck by the operation of the operation mechanism.

Conventionally, in this type of material gripping device, a hydraulic or pneumatic cylinder device or a rotary electric motor is generally employed as a driving unit. For example, in a material gripping device incorporated in a main shaft of an automatic lathe, an operation mechanism is configured to include an operation member movable in an axial direction of the main shaft,
In general, a direct drive output of a cylinder device or a rotational output of an electric motor, which is a driving unit, is transmitted to an operating member via a power transmission mechanism such as a lever assembly or a feed screw device (for example, Japanese Patent Laid-Open No. 7-1995). 328819). In this configuration, the operating member moves in the axial direction along the main shaft by the driving of the driving unit, whereby the gripping portion of the chuck is elastically deformed so as to reduce its inner diameter (that is, to reduce the diameter) and the workpiece is processed. Hold the material.

[0004]

In the above-described conventional material gripping device, when a cylinder device is employed as a driving unit, it is difficult to reduce the overall size of the material gripping device, It is difficult to automatically adjust the gripping force of the chuck immediately in response to changes in the outer diameter and rigidity of the chuck. In addition, the operating efficiency of the chuck tends to decrease due to pressure loss that can occur in the cylinder device itself.

On the other hand, when a rotary electric motor (usually a servomotor) is employed as the drive unit, there is an advantage that the gripping force of the chuck can be automatically adjusted relatively easily by controlling the rotation of the electric motor output shaft. However, since a power transmission mechanism such as a feed screw device is inevitably used, it is still difficult to reduce the overall size of the material holding device. In addition, the feed screw device itself may cause transmission loss due to slippage or twisting, and it is difficult to effectively improve the operation efficiency of the chuck.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a material holding device having a chuck, comprising a drive unit capable of automatically adjusting the holding force of the chuck relatively easily, and further reducing the overall size of the device as much as possible. An object of the present invention is to provide a material gripping device capable of significantly improving operation efficiency. Another object of the present invention is to provide a high-performance automatic lathe provided with such a material gripping device.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, according to the first aspect of the present invention, there is provided a chuck having a gripper capable of opening and closing, an operating mechanism for opening and closing the gripper of the chuck, and an operating mechanism. Provided is a material gripping device including a drive unit for driving a mechanism, wherein the drive unit is provided with a linear motor.

According to a second aspect of the present invention, in the material gripping device of the first aspect, the chuck includes a cylindrical main body having a center axis and an elastically deformable gripping portion provided on the cylindrical main body. The operating mechanism is an operating member that is movable in the axial direction of the cylindrical main body of the chuck, and includes an operating member that elastically deforms the grip portion by moving in the axial direction,
The linear motor provides a material gripping device that moves the operating member in the axial direction by the thrust.

According to a third aspect of the present invention, in the material holding apparatus according to the second aspect, a thrust transmission is provided between the linear motor and the operating member to increase the thrust of the linear motor and transmit the thrust to the operating member. Provided is a material holding device further comprising a device.

According to a fourth aspect of the present invention, in the material holding device of the third aspect, the thrust transmitting device is connected to a mover of a linear motor, and is a linear motion member movable in the axial direction together with the mover. A lever member that engages with the linear member at the first end and engages with the operating member at the second end, and that pivots in association with the axial movement of the linear member. A material gripping device for transmitting a thrust to an actuating member under operation.

According to a fifth aspect of the present invention, in the material holding apparatus of the fourth aspect, the linear motion member has an engagement surface slidably engaged with the first end of the lever member. Provided is a material gripping device having a load reduction area for reducing a load applied to a linear motor via a thrust transmission device while a material is gripped by a gripping portion of a chuck.

According to a sixth aspect of the present invention, there is provided the material holding device according to the second aspect, wherein the linear motor directly applies the thrust to the operating member.

According to a seventh aspect of the present invention, in the material gripping device according to any one of the first to sixth aspects, the operating member comprises a cylindrical body disposed coaxially with the cylindrical main body of the chuck. Thus, the linear motor provides a material gripping device having a cylindrical mover arranged to surround at least a part of the operating member.

According to an eighth aspect of the present invention, in the material gripping device according to any one of the first to seventh aspects, there is provided a thrust control mechanism for adjusting the chucking force of the chuck by controlling the thrust of the linear motor. Further provided is a material gripping device provided.

According to a ninth aspect of the present invention, in the material gripping apparatus according to any one of the first to eighth aspects, the position for adjusting the gripping force of the chuck by controlling the position of the mover of the linear motor. Provided is a material holding device further provided with a control mechanism.

The invention described in claim 10 is the invention according to claims 1 to 9
An automatic lathe characterized in that the material gripping device according to any one of the above items is incorporated in a main shaft.

[0017]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In the drawings, the same or similar components are denoted by common reference numerals. FIG.
FIG. 1 shows a state in which a material holding device 10 according to an embodiment of the present invention is incorporated in a main shaft 12 of an automatic lathe. FIGS. 2 and 3 respectively show a material gripping device 1 incorporated in a main shaft 12.
The main part of 0 is shown enlarged. The material gripping device 10 is configured to open and close a chuck 14, which is concentrically installed in an inner end region of the axial through hole 12a of the main shaft 12, and a grip portion of the chuck 14, which will be described later. : Hereinafter referred to as a bar W).
6 and a drive unit 18 for driving the operating mechanism 16.

The spindle 12 is rotatably mounted on a headstock 22 of an automatic lathe via a bearing device 20. In the illustrated embodiment, a built-in type AC servomotor is built in the headstock 22 as a rotation drive device 24 that drives the spindle 12 to rotate. The main shaft 12 has a hollow cylindrical structure, and the rod W is fed from the rear end into the through hole 12a in the axial direction.
Is held by the chuck 14 at a predetermined position, and is rotationally driven by the rotation driving device 24. The rotary drive device of the spindle 12 is not limited to the illustrated configuration, and an output shaft of an AC servo motor (not shown) provided outside the headstock 22 is connected to a power transmission mechanism (not shown) such as a belt / pulley. ) May be connected to the main shaft 12 via the

As shown in FIG.
A hollow cylindrical main body 26 capable of receiving the rod W therein;
A grip portion 28 provided in a front end (left end in the figure) region of the cylindrical main body 26 in the axial direction. The grip portion 28
It has a slit structure in which the inner diameter can be elastically changed with reference to the central axis 26a of the cylindrical main body 26. That is,
The grip portion 28 includes a plurality of slits 30 formed in the front end region of the cylindrical main body 26 over a predetermined length in the axial direction. The slits 30 are formed by the central axis 2 of the cylindrical main body 26.
Vertical split pieces 32 are formed radially with respect to 6a, are arranged at equal intervals in the circumferential direction, and can be displaced in the radial direction between adjacent slits 30, respectively. Each vertical split piece 32 can be elastically deformed in a plate spring shape in the radial direction of the cylindrical main body 26 with its base end as a fulcrum.

A plurality of vertically split pieces 32 provided on the grip portion 28
Have arcuate curved surfaces on their respective inner surfaces, which cooperate with each other to define a substantially cylindrical bar gripping surface 34 of the gripper 28. The gripping portion 28 uniformly applies an external force inward in the radial direction to the plurality of vertical split pieces 32 to elastically bend and reduce the diameter of the bar gripping surface 34 until the bar gripping surface 34 comes into close contact with the bar W to be gripped. Thus, the bar W is firmly and fixedly held. When the radial pressure on the grip portion 28 is released, the vertical split pieces 32 are elastically restored, the bar grip surface 34 expands, and the bar W is released from the grip portion 28. A tapered surface 36 for receiving an external force inward in the radial direction is formed on an outer surface of each of the vertically split pieces 32 of the grip portion 28. The tapered surfaces 36 cooperate with each other to form a truncated cone-shaped pressure receiving surface that gradually expands and extends toward the front end in the axial direction of the grip portion 28. Further, the tapered surface 36 of each of the vertical split pieces 32 is formed at a position axially rearwardly separated from the front end surface of the grip portion 28 so that the tapered surface 36 is adjacent to the large-diameter end of each tapered surface 36 and has a central axis line. 2
A shoulder surface 38 extending substantially perpendicular to 6a is formed.

The operating mechanism 16 of the material gripping device 10 includes an operating member 40 that is accommodated concentrically in the through hole 12a of the main shaft 12 so as to be slidable in the axial direction. The operating member 40 is a bar W
The chuck 14 can be concentrically accommodated in the front end area inside the axial through hole 40a so as to be axially slidable. Through hole 4 of operating member 40
0a, the gripping portion 2 of the chuck 14
A frusto-conical working surface 42 is formed which can be engaged with all the tapered surfaces 36 provided in FIG. The working surface 42 is
The front end surface is gradually reduced in diameter in the axially rearward direction, and is connected to the cylindrical inner peripheral surface of the operating member 40 at the small diameter end.
The inner diameter of the small diameter end of the working surface 42 is substantially equal to the outer diameter of the small diameter end of the pressure receiving surface formed by the tapered surface 36 of the grip portion 28 of the chuck 14, so that the working surface 42 A pressure surface which is in contact with all the tapered surfaces 36 in a surface contact manner is formed.

An annular support surface 44 extending in the radial direction is formed on the cylindrical inner peripheral surface of the operating member 40 at a position axially rearward from the operating surface 42 by a predetermined distance.
The chuck 14 and the elastic member 46 are accommodated concentrically in the area between the support member 44 and the chuck 14 and the elastic member 46 in the axial direction. The elastic member 46 is made of, for example, a compression coil spring, and is interposed between the axial rear end face of the chuck 14 and the support surface 44 of the operating member 40 in an elastically bent state, and connects the chuck 14 to the operating member 40. It is urged in a direction away from the support surface 44 (that is, forward in the axial direction of the main shaft 12).

At the tip of the spindle 12, a locking surface 48 engageable with all the shoulder surfaces 38 provided on the grip portion 28 of the chuck 14.
Is detachably attached. The chuck 14 is located in the axial front end region of the operating member 40.
And the elastic member 46 properly accommodated, the cap 5
0 is attached to the tip of the main shaft 12, the locking surface 48 engages with the entire shoulder surface 38 of the chuck 14, and holds the chuck 14 from falling off the operating member 40 against the bias of the elastic member 46. I do. When replacing the chuck 14, the cap 50 is removed from the spindle 12 and the chuck 1 is removed.
4 may be removed from the operating member 40.

As shown on an enlarged scale in FIG.
The rear end surface 40b in the axial direction of the drive line constitutes a driving force receiving surface that receives the driving force from the driving unit 18. In the vicinity of the rear end in the axial direction of the main shaft 12, a plurality of openings 52 penetrating the cylindrical wall of the main shaft 12 are preferably provided at equal intervals in the circumferential direction. Axial rear end face 40
b is located. As will be described later, the actuating member 40 receives the driving force of the driving unit 18 in the through hole 12a of the main shaft 12 and receives the driving force of the driving unit 18 in the axial direction of the main shaft 12, that is, the chuck 1.
4 moves in the axial direction of the cylindrical main body 26 (FIG. 2), whereby the grip portion 28 (FIG. 2) of the chuck 14 is elastically reduced in diameter. In the illustrated embodiment, the operating member 40 has a three-part structure divided in the vicinity of the support surface 44 (FIG. 2) and the vicinity of the rear end surface 40b. However, the present invention is not limited to this. Can also be provided.

The drive section 18 of the material holding device 10 is equipped with a linear motor 54. The linear motor 54 includes a cylindrical linear motor (for example, a linear step motor), and includes a cylindrical movable element 56 concentrically surrounding an axial rear end region of the main shaft 12 and the operating member 40; And a stator 60 that is fixedly installed on the inner surface of the housing 58 of the 22 and faces the mover 56 via a gap. In the illustrated embodiment, the linear motor 54 is
Although 0 is defined as the primary side and the mover 56 is configured as the secondary side, the configuration may be reversed. As will be described later, the linear motor 54
To actuate the operating member 40 in the axial direction of the main shaft 12, that is, in the axial direction of the cylindrical main body 26 of the chuck 14.

The material gripping device 10 is further provided between the linear motor 54 and the operating member 40,
4 is provided with a thrust transmitting device 62 for increasing the thrust and transmitting the thrust to the operating member 40. The thrust transmitting device 62 is connected to the mover 56 of the linear motor 54, and is connected to the linear motion member 64 that can move in the axial direction of the main shaft 12 integrally with the mover 56, and that the thrust transmission device 62 moves in the axial direction of the linear motion member 64. And a plurality of lever members 66 that pivot on the support shaft.

The linear motion member 64 of the thrust transmitting device 62 is a cylindrical body disposed concentrically inside the mover 56 of the linear motor 54, and its inner peripheral surface 64 a is formed on the cylindrical wall of the main shaft 12. The main shaft 12 is attached concentrically to the main shaft 12 at the rear end region in the axial direction of the main shaft 12 by slidingly contacting the outer peripheral surface 12b. The translation member 64 further includes a flange portion 68 projecting radially outward at one axial end of the translation member 64, and a flange portion 68.
And a substantially conical outer peripheral surface, that is, an engaging surface 70, which is formed adjacent to the outer peripheral surface and gradually decreases in diameter toward the other end in the axial direction of itself. The linear motion member 64 is fixedly connected at its flange portion 68 to a cylindrical support member 72 that directly supports the mover 56 of the linear motor 54. The linear motion member 64 is properly mounted on the main shaft 12,
The engaging surface 70 is arranged so that the diameter thereof gradually decreases toward the rear end in the axial direction of the main shaft 12.

The plurality of levers 66 of the thrust transmission device 62
At a position axially rearward of the linear motion member 64, they are preferably arranged at equal intervals in the circumferential direction along the outer peripheral surface 12 b of the main shaft 12. Each lever 66 has a first end 6 that engages with a linear member 64.
6a and a second end 66b engaged with the actuating member 40. The lever holder 7 is provided at an intermediate point between the first end 66a and the second end 66b in an axial rear end region of the main shaft 12.
4 is rotatably supported by a support shaft 76. When the distance between the first end 66a and the support shaft 76 is
Much larger than the distance between the end 66b and the support shaft 76,
With the support shaft 76 as a fulcrum, the function of leverage can be exhibited.

Each lever 66 can be slidably engaged with the engagement surface 70 of the linear motion member 64 with its first end 66a properly attached to the main shaft 12 via the lever holder 74. Placed in the position. In this state, each lever 66
The second end 66b is received in a corresponding opening 52 formed in the rear end region of the main shaft 12, and slidably engages with the axial rear end surface 40b of the actuating member 40 located in the opening 52. I do. At this time, as described above, when the cap 50 is attached to the distal end of the main shaft 12 in a state where the chuck 14 and the elastic member 46 are properly accommodated in the axial front end region of the operating member 40, under the urging force of the elastic member 46, The shoulder surface 38 of the chuck 14 is brought into contact with the locking surface 48 of the cap 50, and at the same time, under the reaction force of the elastic member 46, the axial rear end surface 40 b of the operating member 40 is brought into contact with the second end 66 b of each lever 66. Be abutted. Thereby, each lever 66 is urged in a direction in which the first end 66 a approaches the outer peripheral surface 12 b of the main shaft 12, and the lever holder 74 is connected to the rear end of the main shaft 12 in the axial direction through the plurality of levers 66. It is urged toward.

As shown in FIG. 4, the lever holder 74
The guide pin 78 provided on itself is engaged with the guide hole 80 provided in the cylindrical wall of the main shaft 12, whereby the main shaft 12 is rotated.
Is mounted on the outer peripheral surface 12b so as to be slidable in the axial direction. Behind the lever holder 74 in the axial direction, an adjusting nut 82 screwed into the axial rear end region of the cylindrical wall of the main shaft 12.
Is installed. The adjustment nut 82 holds the lever holder 74 at a predetermined position on the main shaft 12 against the urging force of the elastic member 46 applied to the lever holder 74 via the operating member 40 and the plurality of levers 66. In this state where the biasing force of the elastic member 46 is applied to the lever holder 74, the adjustment nut 82 is tightened or loosened on the main shaft 12, so that the lever holder 74 on the main shaft 12 is rotated.
In addition, the axial position of the plurality of levers 66 can be adjusted.

The linear motion member 64 slides in the axial direction on the outer peripheral surface 12b of the main shaft 12 by driving the linear motor 54, as will be described later. The plurality of levers 66 are synchronously rotated around the respective support shafts 76 by sliding the one end 66a on the sliding type. Here, as shown in an enlarged manner in FIG. 5A, the angle formed between the engagement surface 70 of the linear motion member 64 and the inner peripheral surface 64a (that is, the outer peripheral surface 12b of the main shaft 12) increases stepwise. The diameter of the main shaft 12 is gradually reduced toward the rear end in the axial direction. In the illustrated embodiment, the engagement surface 70 includes a first region 70a closest to the flange portion 68 and extending substantially parallel to the inner peripheral surface 64a, and an inner peripheral surface adjacent the rear of the first region 70a. About 5 ° for 64a
A second region 70b extending at an angle of
b, a third region 70c extending at an angle of about 10 ° to the inner peripheral surface 64a, and a rear region adjacent to the third region 70c, about 25 ° to the inner peripheral surface 64a. And a fourth region 70d extending at an angle. With such a configuration, the engagement surface 70 of the linear motion member 64 has its first and second regions 70a, 70b, in particular, as described later, during the rod material gripping through the linear motor 54 Can be reduced.

An operation mode of the material gripping device 10 having the above configuration will be described below. First, the operating member 40 is arranged at the chuck open position by the initial setting of the linear motor 54 constituting the drive unit 18, and the grip unit 28 of the chuck 14 is set in the open state. In this state, as shown in FIGS. 1 and 3, the mover 56 of the linear motor 54 is disposed at the front end (the left end in the figure) of the linear reciprocating stroke together with the linear motion member 64 of the thrust transmission device 62. . Further, the engagement surface 70 of the translation member 64 is disposed at a position slightly away from the first ends 66a of the plurality of levers 66 in the axial direction forward, so that the first ends 66a of the levers 66 are Under the urging force of FIG. 5 (FIG. 5A).
Then, the working surface 42 of the operating member 40 is placed at a position where the tapered surface 36 of the grip portion 28 of the chuck 14 is not substantially pressed (FIGS. 1 and 2). During this open state, the spindle 1
A long bar W is inserted into the inside of the chuck 2 from the rear end of the chuck 2 and fed to the chuck 14 through the through hole 40 a of the operating member 40.

When the required processing length of the bar W projects from the front end face in the axial direction of the chuck 14, the feeding of the bar W is stopped. Therefore, the linear motor 54 is started, and
The mover 56 and the linear motion member 64 are moved rearward in the axial direction of the main shaft 12. Accordingly, the lever holder 74
A plurality of levers 66 are progressively mounted on the engagement surfaces 70 of the linear motion members 64 at their first ends 66a against the bias of the elastic members 46, so that the support shaft 76 is centered. Rotate in synchronization with. When the plurality of levers 66 rotate in this manner, the levers 66 increase the thrust of the linear motor 54 under the action of the lever and transmit the thrust to the operating member 40, and the operating member 40 at each second end 66b. Is pressed on the rear end face 40b in the axial direction. Thereby, the operating member 40
The through hole 1 of the main shaft 12 against the bias of the elastic member 46.
It moves inside 2a toward the front in the axial direction.

Thereafter, the mover 56 and the linear motion member 64
When reaching the rear end (right end in the figure) position of the linear reciprocating stroke, the operating member 40 is located at the chuck closed position, and the grip portion 28 of the chuck 14 is closed (FIG. 4). In this state, the working surface 42 of the actuating member 40 is pressed against the entire tapered surface 36 of the grip portion 28 of the chuck 14, whereby the entire vertical split piece 32 of the grip portion 28 is uniformly bent radially inward. The diameter of the bar holding surface 34 is reduced, and the bar W is firmly and fixedly held on the holding portion 28. In this chuck closed position, the first end 66a of each lever 66 is under the urging force of the elastic member 46, and the first area 70a (FIG. 5B) of the engagement surface 70 of the linear motion member 64 or the The two regions 70b (FIG. 5)
(C)).

Here, when the first end 66a of each lever 66 is in contact with the first area 70a of the engaging surface 70 of the linear motion member 64 (FIG. 5B), the operating member 40 and the lever The reaction force of the bar gripping force and the urging force of the elastic member 46 applied to the linear motion member 66 via the
6a acts so as to press against the first engagement surface 70a parallel to the outer peripheral surface 12b of the main shaft 12.
There is substantially no component force for urging the shaft 4 forward in the axial direction of the main shaft 12. Therefore, in this state, the linear motor 54
Is substantially zero, and as a result, the excitation of the linear motor 54 can be stopped.

On the other hand, when the first end 66a of each lever 66 is in contact with the second area 70b of the engaging surface 70 of the linear motion member 64 (FIG. 5C), the operating member 40 and the lever 6
The reaction force of the bar gripping force and the urging force of the elastic member 46 applied to the linear motion member 66 via the
a acts on the engagement surface second region 70b inclined with respect to the outer peripheral surface 12b of the main shaft 12, so that the component force for urging the linear motion member 64 forward in the axial direction, that is, the load applied to the linear motor 54 Occurs. However, since the inclination angle of the second region 70b with respect to the main shaft outer peripheral surface 12b is as small as about 5 °, the load applied to the linear motor 54 is relatively small, and as a result, the chuck 14 is held in the closed state by the small thrust of the linear motor 54. it can. Thus, the first and second regions 70a, 70b of the engagement surface 70 of the linear motion member 64
Functions as a load reduction area for reducing the load applied to the linear motor 54 via the thrust transmission device 62 while the bar W is being gripped by the gripper 28 of the chuck 14.

From the above-mentioned closed state, the linear motor 54 is started, and the movable element 56 is moved together with the linear motion member 64 onto the main shaft 1.
2 forwards in the axial direction, the plurality of levers 66
Are, under the biasing force of the elastic members 46, their first ends 66a.
Is slid along the engagement surface 70 of the linear motion member 64, whereby the first end 66 a rotates in synchronization with the spindle 76 in a direction to approach the main shaft outer peripheral surface 12 b. Accordingly, the operating member 40 moves rearward in the axial direction within the through hole 12a of the main shaft 12 by the urging force of the elastic member 46. As a result, the working surface 42 of the operating member 40
The pressure applied to the entire tapered surface 36 of the gripping portion 28 of No. 4 is released, the diameter of the bar gripping surface 34 of the gripping portion 28 increases, and the bar W is released from the chuck 14.

As described above, according to the material gripping device 10 having the above-described configuration, since the linear motor 54 is provided in the drive unit 18 for driving the operating member 40 of the operating mechanism 16, a conventional cylinder device is employed as the drive unit. Compared with the configuration of the material gripping device described above, it is easy to reduce the overall size of the material gripping device 10, and the operating efficiency of the chuck 14 can be significantly improved by eliminating the pressure loss of the cylinder device. In addition, the linear motion control of the output shaft (the support member 72 in the illustrated embodiment) of the linear motor 54 (described later).
Thus, there is an advantage that the gripping force of the chuck 14 can be automatically adjusted relatively easily in response to a change in the outer diameter dimension or rigidity of the bar W immediately. In addition, the power transmission mechanism can be simplified by eliminating the feed screw device, so that the overall size of the material gripping device 10 can be easily reduced as compared with a conventional material gripping device employing a rotary motor as a drive unit. With
By eliminating the transmission loss of the feed screw device, the operating efficiency of the chuck can be effectively improved. Therefore, in an automatic lathe in which the material gripping device 10 is incorporated in the main shaft 12, downsizing and high functionality are promoted.

In particular, since the material holding device 10 employs the cylindrical linear motor 54, there is no need to consider the positioning of the mover 56 with respect to the stator 60 in the rotational direction. Therefore, the mover 56 connected to the linear motion member 64 slidably in contact with the main shaft 12 can rotate together with the main shaft 12, and a bearing is interposed between the mover 56 and the linear motion member 64. Since the necessity is eliminated, the miniaturization of the device and the simplification of the structure are further promoted. Further, as a characteristic of the cylindrical linear motor 54 itself, since the magnetic attraction force is offset and does not affect the thrust, there is an advantage that eccentricity due to the magnetic attraction force during rotation of the main shaft can be reliably prevented.

The above-described material holding device 10 includes the chuck 1
As means for automatically adjusting the gripping force of No. 4, a thrust control mechanism 84 for controlling the linear motion of the output shaft by controlling the thrust of the linear motor 54 can be further provided. In the material gripping device 10, the thrust of the linear motor 54 provided in the drive unit 18 is transmitted to the chuck 14 via the thrust transmitting device 62 and the operating mechanism 16, and
Therefore, the gripping force of the chuck 14 is proportional to the thrust of the linear motor 54.

As shown in FIG. 6, the thrust control mechanism 84
A thrust measuring unit 86 for measuring an actual thrust during operation of the linear motor 54, and a thrust setting unit 8 for presetting a thrust target value of the linear motor 54 for generating a required gripping force.
8, a thrust storage unit 90 for storing the thrust target value set by the thrust setting unit 88, and whether or not the actual thrust measured by the thrust measurement unit 86 has reached the thrust target value stored in the thrust storage unit 90 , An open position storage unit 94 that stores the position of the linear motion member 64 at the chuck open position (FIG. 5A), a thrust measurement unit 86, the determination unit 92, and the closed position storage unit 94. A control unit 96 for calculating the received information to control the operation of the linear motor 54;
And a display unit 98 for displaying the processing results in step 6.

The control unit 96 can be composed of, for example, a CPU of a numerical control (NC) device mounted on an automatic lathe.
The operation of the linear motor 54 can be controlled according to the timing chart shown in FIG. 7 stored in advance in the storage unit of the device. In this case, the thrust setting unit 88 can be constituted by an input unit of the NC device, and the operator can input a target thrust value of the linear motor 54 by a key. The display section 98
Can be constituted by a display unit of the NC device, and can display a relative positional relationship between the linear motion member 64 and the plurality of levers 66, a thrust of the linear motor 54, and the like.

Next, the chuck 1 by the thrust control mechanism 84
An example of the operation control and grip force adjustment procedure of No. 4 will be described. First, at the chuck open position where the chuck 14 does not grip the bar W, the relative positional relationship between the linear motion member 64 of the thrust transmission device 62 and the plurality of levers 66 is adjusted by operating the adjustment nut 82. At this time, as shown in FIG. 5A, the linear motion member 64 and each lever 66 may be arranged so as to be slightly separated from each other in the axial direction. Because it rotates easily on 12,
Outer peripheral surface 12b of main shaft 12 and inner peripheral surface 64 of linear motion member 64
There is a concern that a may wear over time. Therefore, at the chuck open position, the first end 66a of each lever 66 is
It is preferable to slightly ride on the fourth region 70d of the fourth engaging surface 70. The position of the linear motion member 64 at the chuck open position is instructed to the linear motor 54 by pulse number data input through an input unit of the NC device, for example, and is stored in the open position storage unit 94. Since then
When shifting from the chuck closed position to the chuck open position, the control unit 96 reads the open position data of the linear motion member 64 stored in the open position storage unit 94 and reads the linear motor 54.
Operation control.

In the thrust setting section 88, as the thrust target value of the linear motor 54, a proper thrust value Q1 for obtaining a proper chuck gripping force with respect to a bar W having a predetermined size, and a maximum value slightly larger than the proper thrust value Q1. Thrust value Q2 and proper thrust value Q
A holding thrust value Q3 for holding the bar gripping state after the chuck 14 is closed,
These thrust values Q1, Q2, Q3 (FIG. 7) are stored in the thrust storage unit 9.
Store to 0. As shown in FIG. 7, the control unit 96 starts the linear motor 54 based on the ON signal of the chuck closing operation, and moves the movable element 56 and the linear motion member 64 to the specified speed V1.
Then, from the above-described chuck open position to the chuck closing direction (FIG. 3)
To the right). Accordingly, as described above, the plurality of levers 66 gradually ride on the engagement surfaces 70 of the linear motion members 64 at their first ends 66a and rotate synchronously, and press the operating member 40 at the second ends 66b. Then, the main shaft 12 is moved forward in the axial direction. During this time, the thrust of the linear motor 54 gradually increases in response to the increase in the load.

The chuck 14 shifts to the closed state by the movement of the operating member 40. At this time, the linear motor 54 is operated at the speed V1 until the thrust exceeds the appropriate thrust Q1 and reaches the maximum thrust Q2. And the linear motor 5
When the thrust of No. 4 reaches the maximum thrust value Q2, the linear motor 54 is temporarily stopped, and the forward movement of the operating member 40 is terminated. In this state, the plurality of levers 66 of the thrust transmission device 62 are in contact with the second regions 70b of the engagement surfaces 70 of the linear motion members 64 at their first ends 66a.

Immediately after that, the control unit 96 controls the linear motor 5
4 is operated so that the mover 56 slightly moves in the opposite direction (left direction in FIG. 3) at the speed V2. Thereby,
The stress accumulated between the thrust transmitting device 62 and the chuck 14 is released without substantially moving the operating member 40, and the thrust of the linear motor 54 is slightly reduced. Then, the thrust of the linear motor 54 is adjusted to the appropriate thrust value Q.
At the time point when the number decreases to 1, the linear motor 54 is stopped.
Thus, the closing operation of the chuck 14 is completed.

After the chuck 14 is closed, the linear motor 5
4 continues to generate the proper thrust value Q1, there is a concern that an unnecessarily large load is applied to the linear motor 54 to cause overheating. Therefore, after the closing operation of the chuck 14 is completed, the thrust of the linear motor 54 is reduced to a holding thrust value Q3 sufficient to hold the chuck 14 in the bar material holding state. Therefore, the bar W held by the chuck 14 is processed while the linear motor 54 is generating the holding thrust value Q3. In the chuck closed state, when the first ends 66a of the plurality of levers 66 are in contact with the first area 70a of the engagement surface 70 of the linear motion member 64, the holding thrust Q3
May be substantially zero.

As described above, according to the thrust control mechanism 84,
Thrust values Q1, Q2, Q preset in thrust setting section 88
By appropriately selecting 3, the relative position between the linear motion member 64 and the plurality of levers 66 in the chuck closed state and the axial position of the operating member 40 are adjusted, thereby changing the gripping force of the chuck 14. Can be. Therefore, even in the middle of the processing process, the gripping force of the chuck 14 can be automatically adjusted as needed in response to a change in the outer diameter or rigidity of the bar W immediately.

The above-described material holding device 10 includes the chuck 1
As another means for automatically adjusting the gripping force of No. 4, a position control mechanism 100 for controlling the linear movement of the output shaft by controlling the position of the mover 56 of the linear motor 54 can be further provided. In the material gripping device 10, when the linear motor 54 provided in the drive unit 18 is a servomotor, a position detector for feedback control is provided.
00 can be configured.

As shown in FIGS. 3 and 4, the position control mechanism 100 includes at least one non-contact sensor 102 installed at an axial rear end region of the housing 58 of the headstock 22.
And an extension member 104 that is fixed to a support member 72 that supports the mover 56 of the linear motor 54, extends rearward in the axial direction, and is disposed so as to be able to face the sensing unit 102 a of the non-contact sensor 102. When the linear motor 54 is a servo motor, the non-contact sensor 102 and the extension member 104 can constitute a position detector for feedback control. In this case, for example, the detection signal of the non-contact sensor 102 is sent to the control unit of the NC device mounted on the automatic lathe.

The non-contact sensor 102 can be composed of, for example, an eddy current displacement meter or a laser displacement meter. The extension member 104
It has a truncated conical outer surface 104a whose diameter gradually decreases toward the rear in the axial direction of the main shaft 12, and forms a variable gap between the outer surface 104a and the sensing portion 102a of the non-contact sensor 102. When the mover 56 of the linear motor 54 is at the front end position of the above-described linear reciprocating stroke of the thrust transmitting device 62, the gap between the sensing portion 102a of the non-contact sensor 102 and the outer peripheral surface 104a of the extension member 104 is maximum. At this time, the translation member 64 and the operating member 40 are placed at the chuck open position (FIG. 3). In addition, the linear motor 54
When the mover 56 is at the rear end position of the above-described linear reciprocating stroke of the thrust transmitting device 62, the non-contact sensor 1
02 sensing portion 102a and outer peripheral surface 104 of extension member 104
a of the linear motion member 6
4 and the actuating member 40 are in the chuck closed position (FIG. 4). While the linear motion member 64 and the operating member 40 move between the chuck open position and the chuck closed position, the sensing portion 102a of the non-contact sensor 102 and the outer peripheral surface 10 of the extension member 104 are moved.
4a changes continuously, and the non-contact sensor 102 continuously outputs a signal corresponding to the gap size.

As described above, according to the position control mechanism 100, the position of the mover 56 of the linear motor 54 is appropriately selected based on the signal output from the non-contact sensor 102, so that the linear motion in the chuck closed state is achieved. By adjusting the relative position between the member 64 and the plurality of levers 66 and the axial position of the operating member 40, the gripping force of the chuck 14 can be changed. Therefore, even in the middle of the machining process, the chuck 1 can immediately respond to changes in the outer diameter and rigidity of the bar W.
4 can be automatically adjusted as needed. The use of the non-contact sensor 102 in the position control mechanism 100 depends on the use of the movable element 56 of the linear motor 54 and the extension member 104.
Are allowed to rotate together with the main shaft 12. Therefore, the position control mechanism can also be configured by attaching a contact sensor that senses the axial position of the extension member 104 in a contact manner to the housing 58 via, for example, a bearing.

FIG. 8 shows a material holding device 110 according to another embodiment of the present invention. The material gripping device 110 has substantially the same configuration as the material gripping device 10 described above, except for the configuration of the drive unit 112. Therefore, corresponding components are denoted by common reference numerals and description thereof is omitted.

The driving unit 112 of the material holding device 110 includes:
A linear motor 114 is provided. Linear motor 114
Is a flat linear motor (for example, a linear step motor), and is a flat-plate-shaped movable element 1 which is arranged substantially parallel to and separated from the rear end region of the main shaft 12 and the operating member 40 in the axial direction.
16 and a flat plate-shaped stator 118 fixedly installed on the inner surface of the housing 58 of the headstock 22 and facing the mover 116 via a gap. In the illustrated embodiment, the linear motor 114 is configured such that the stator 118 is on the primary side and the mover 116 is on the secondary side, but the configuration may be reversed.

The mover 116 of the linear motor 114 is fixedly supported by a support member 120, and the support member 120 is rotatably connected to the linear motion member 64 of the thrust transmission device 62 via a bearing 122. Accordingly, while the linear motion member 64 can move in the axial direction of the main shaft 12 integrally with the mover 116, it can rotate with the main shaft 12 with respect to the mover 116.

According to the material gripping device 110 having the above-described configuration, similarly to the material gripping device 10 described above, it is easy to reduce the overall size of the material gripping device 110, and the operating efficiency of the chuck 14 is significantly improved. be able to. Further, the thrust control mechanism 84 and the position control mechanism 10
By incorporating 0, the output shaft of the linear motor 114 (the support member 120 in the illustrated embodiment) is controlled linearly as described above, so that the gripping force of the chuck 14 can be easily and automatically adjusted.

FIG. 9 shows a material holding device 130 according to still another embodiment of the present invention. The material holding device 130 is
Except for the configuration of the operating mechanism 132 and the drive unit 134, the configuration has substantially the same configuration as the above-described material gripping device 10,
Corresponding components are denoted by common reference numerals, and description thereof is omitted.

The operating mechanism 132 of the material holding device 130 is
An actuating member 136 is provided in the axial front end region of the through hole 12a of the main shaft 12 so as to be axially slidably accommodated concentrically. The operating member 136 corresponds to the front end side element divided near the support surface 44 of the operating member 40 of the material holding device 10 described above, and has an axial through hole 13.
The chuck 14 can be concentrically housed in the chuck 6a so as to be slidable in the axial direction. In the axial front end region of the through hole 136a of the operation member 136, a truncated cone-shaped operation surface 42 that can be engaged with the entire tapered surface 36 provided on the grip portion 28 of the chuck 14 is formed.

The driving section 134 is equipped with a linear motor 138. The linear motor 138 is composed of a cylindrical linear motor (for example, a linear step motor),
And a stator that is fixedly installed on the inner surface of the housing 58 of the headstock 22 and faces the mover 140 via a gap. 142. In the illustrated embodiment, the linear motor 138 is configured such that the stator 142 is on the primary side and the mover 140 is on the secondary side, but the configuration may be reversed.

In the material holding device 130, the material holding device 1
The thrust transmission device 62 provided at 0 is omitted. Instead, the mover 140 of the linear motor 138 is fixedly supported by the support member 144 and has a plurality of operating claws 146 installed at the front end in the axial direction of the support member 144.
Fixedly connected to The support member 144 is a cylindrical body disposed concentrically inside the mover 140 of the linear motor 138, and has an inner peripheral surface 144 a slidably in contact with an outer peripheral surface 12 b of the cylindrical wall of the main shaft 12. Then, it is attached concentrically to the main shaft 12 in the axially intermediate region of the main shaft 12. The plurality of operating claws 146 are fixed to the front end surface in the axial direction of the support member 144, preferably at regular intervals in the circumferential direction. Each of the operating claws 146 has a pressing portion 146a that protrudes radially inward from the inner peripheral surface 144a of the support member 144 and extends in the axial direction of the support member 144.

In the axially intermediate region of the spindle 12, the spindle 1
A plurality of openings 148 passing through the two cylindrical walls are preferably provided at equal intervals in the circumferential direction. Multiple operating claws 146
The pressing portions 146a are inserted into the through holes 12a of the main shaft 12 through the corresponding openings 148 of the main shaft 12. In this state, the pressing portions 14 of the operating claws 146 are
6a, the respective axial ends are engaged with the axial rear end surface of the operating member 136, and the respective radial end surfaces 146b are separated from each other by a distance that allows the workpiece to be inserted in the main shaft 12. Thus, the plurality of operating claws 146 move in the axial direction of the main shaft 12 integrally with the mover 140 of the linear motor 138, and
Can be directly transmitted to the operating member 136.

According to the material gripping device 130 having the above-described configuration, the overall size of the material gripping device 130 can be further reduced as compared with the above-described material gripping device 10 because the thrust transmitting device 62 is omitted. Moreover, the thrust transmission device 6
2, the operating efficiency of the chuck 14 is further improved. In addition, by incorporating the thrust control mechanism 84 and the position control mechanism 100 to control the linear motion of the output shaft of the linear motor 138 (the support member 144 in the illustrated embodiment) as described above, the gripping force of the chuck 14 becomes more subtle. Adjustment can be easily performed. However, this configuration increases the thrust of the linear motor 138 to increase the operating member 13.
Therefore, it can be effectively used for applications requiring a relatively small gripping force, such as a small-diameter material such as a watch part, a hollow material, or a material that does not like scratches on the outer surface.

FIG. 10 shows a material holding device 150 according to still another embodiment of the present invention. Material holding device 150
Has substantially the same configuration as that of the above-described material gripping device 10 except for the configurations of the operating mechanism 152 and the thrust transmission device 154. Therefore, corresponding components are denoted by common reference numerals and description thereof is omitted. .

The material gripping device 150 is different from the material gripping devices 10, 110 and 130 described above in that the operating mechanism 152
Actuating member 156 fixedly connected to chuck 14
And the thrust transmitting device 154 transmits the thrust of the linear motor 54 to the operating member 156,
By moving the 56 integrally with the chuck 14 rearward in the axial direction of the main shaft 12, the chuck 14 is configured to shift from the open state to the closed state. Therefore, in the axial front end region of the main shaft 12, the tapered working surface 1 that can be engaged with the entire tapered surface 36 on the outer periphery of the grip portion of the chuck 14 is provided.
58 are formed. Linear member 64 of thrust transmission device 154
The plurality of levers 66 are installed in the axial rear end region of the main shaft 12 in a relative arrangement opposite to the above-described relative arrangement in the thrust transmission device 62. When gripping the workpiece,
By driving the linear motor 54, the operating member 156 is moved together with the chuck 14 in a direction of being drawn into the main shaft 12, and the tapered surface 36 of the chuck 14 is pressed against the working surface 158 at the tip of the main shaft 12, thereby obtaining a desired gripping force. . It is understood that the same operation and effect as the operation and effect of the material gripping device 10 described above are also achieved in such a configuration.

[0065]

As is apparent from the above description, according to the present invention, a material holding device having a chuck is provided with a drive unit capable of automatically adjusting the chucking force of the chuck relatively easily, and furthermore, the overall size of the device. And the operating efficiency of the chuck can be significantly improved. Therefore, if this material gripping device is incorporated into an automatic lathe, a small, high-performance automatic lathe is provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a state in which a material holding device according to an embodiment of the present invention is incorporated in a headstock of an automatic lathe.

FIG. 2 is an enlarged cross-sectional view showing a chuck and its peripheral portion of the material holding device of FIG.

FIG. 3 is an enlarged cross-sectional view showing a driving unit of the material holding device of FIG. 1 and a peripheral part thereof, showing a chuck open state.

FIG. 4 is a sectional view corresponding to FIG. 3, showing a chuck closed state.

FIGS. 5A and 5B are partially enlarged cross-sectional views illustrating the operation of the thrust transmitting device of the material gripping device of FIG.
(B) shows a chuck closing position, and (c) shows other chuck closing positions.

FIG. 6 is a block diagram showing a configuration of a thrust control mechanism that can be provided in the material holding device of FIG. 1;

7 is a diagram illustrating an example of an operation of a drive unit for controlling a chuck closing operation by the thrust control mechanism in FIG. 6;

FIG. 8 shows a material holding device according to another embodiment of the present invention.
It is a schematic sectional drawing shown in the state where it was built in the headstock of an automatic lathe.

FIG. 9 is a schematic cross-sectional view showing a state in which a material holding device according to still another embodiment of the present invention is incorporated in a headstock of an automatic lathe.

FIG. 10 is a schematic cross-sectional view showing a state in which a material holding device according to still another embodiment of the present invention is incorporated in a headstock of an automatic lathe.

[Explanation of symbols]

 10, 110, 130, 150: Material gripping device 12: Spindle 14: Chuck 16, 132, 152: Actuating mechanism 18, 112, 134: Drive unit 40, 136, 156: Actuating member 46: Elastic member 54, 114, 138 ... linear motors 56, 116, 140 ... movers 60, 118, 142 ... stators 62, 154 ... thrust transmission device 64 ... linear motion members 66 ... levers 70 ... engagement surfaces 72, 120, 144 ... support members 84 ... thrusts Control mechanism 100: Position control mechanism 146: Actuating claw

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Kunihiko Kokubo, Inventor 6-1-1-12, Tanashi-cho, Nishi-Tokyo, Tokyo Citizen Watch Co., Ltd. F-term (reference) 3C007 AS12 CY36 ES15 HS26 HT33 HT35 KS03 KV08 KV11 LV10 NS07 3C032 GG27 GG32

Claims (10)

[Claims] 1. A material gripping device comprising: a chuck having a gripper capable of opening and closing operation; an operating mechanism for opening and closing the gripper of the chuck; and a drive unit for driving the operating mechanism. A material gripping device characterized by being equipped with a linear motor. 2. The chuck has a cylindrical main body having a central axis, and the elastically deformable grip portion provided on the cylindrical main body, and the operating mechanism includes an axis of the cylindrical main body of the chuck. An actuating member movable in the axial direction, the actuating member being configured to elastically deform the grip portion by moving in the axial direction, wherein the linear motor moves the operating member in the axial direction by a thrust. Item 1. The material holding device according to Item 1. 3. The material grip according to claim 2, further comprising a thrust transmitting device installed between the linear motor and the operating member, for increasing the thrust of the linear motor and transmitting the thrust to the operating member. apparatus. 4. The thrust transmitting device is connected to a mover of the linear motor, and is connected to a linear member movable in the axial direction together with the movable member, and is engaged with the linear member at a first end. A lever member that engages with the operating member at a second end and pivots in association with the axial movement of the translation member;
4. The apparatus according to claim 3, wherein the lever member transmits the thrust to the operating member under the action of a lever. 5. The linear motion member has an engagement surface slidably engaged with the first end of the lever member, and the engagement surface grips a material on the grip portion of the chuck. 5. The material gripping device according to claim 4, further comprising a load reduction area for reducing a load applied to the linear motor via the thrust transmission device during the operation. 6. The apparatus according to claim 2, wherein the linear motor directly applies the thrust to the operating member. 7. The operating member comprises a cylindrical body disposed coaxially with the cylindrical main body of the chuck, and the linear motor includes a tube disposed so as to surround at least a part of the operating member. The material gripping device according to any one of claims 1 to 6, further comprising a movable element. 8. The material gripping device according to claim 1, further comprising a thrust control mechanism for adjusting a gripping force of the chuck by controlling a thrust of the linear motor. 9. The material gripping device according to claim 1, further comprising a position control mechanism for adjusting a gripping force of the chuck by controlling a position of a mover of the linear motor. 10. An automatic lathe wherein the material gripping device according to claim 1 is incorporated in a main shaft.