JP3407191B2 - Pallet changer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pallet exchanging device used for automatic exchanging of works in a machine tool such as a machining center.

[0002]

2. Description of the Related Art As a pallet exchanging device, the one disclosed in Japanese Patent Laid-Open No. 61-65747 has been proposed.
What is described in the above publication is that the pallet on which the processed work is placed and the work to be processed are placed on both sides of the turning center of the pair of left and right turning arms rotatably provided in the horizontal plane. A pallet rotating mechanism that supports the respective pallets and that rotates the rotating arms to exchange the positions of both pallets; a machining position that faces the spindle head of the machine tool and an exchange position that faces the pallet rotating mechanism. In between, a pallet moving mechanism for moving the pallet on which the work is placed on the working table together with the working table, and an elevating mechanism for raising and lowering the revolving arm are provided.

According to the pallet changing device,
With the pallet on which the workpiece machined by the machine tool is placed on the machining table, the pallet moving mechanism moves the pallet from the machining position facing the spindle head of the machine tool to the exchange position facing the pallet turning mechanism. Next, the lifting mechanism is operated to raise the swing arm of the pallet swing mechanism, and the pallet in the exchange position is supported and engaged on the swing arm. After that, the pallet turning mechanism is operated to turn the turning arm 180 degrees, and the positions of the pallet on which the processed work is placed and the position of the pallet on which the work to be processed are placed are exchanged. Then, the lifting mechanism is operated again to lower the swing arm,
The pallet on which the work to be processed is placed,
Bring it to a position where it can be engaged with the processing table. And
The pallet is clamped on the machining table and the pallet moving mechanism is operated to reach the machining position facing the spindle head of the machine tool for machining the workpiece placed on the pallet. Hereinafter, by repeating the above operation, the automatic exchange of the pallets can be continuously performed.

[0004]

The above-mentioned conventional pallet exchanging device has the following problems. That is, a pallet moved from a machining position facing the spindle head of the machine tool to a replacement position facing the pallet rotating mechanism is transferred from the processing table to the rotating arm, or vice versa. In order to transfer the machine from the turning arm to the processing table, it is necessary to provide an elevating mechanism to elevate the rotating arm, and the structure becomes complicated accordingly, and a space for arranging the elevating mechanism must be secured. There was a problem that the device became large. In addition, there is a problem in that it takes a long time to replace the pallet because a step of operating the lifting mechanism to lift and lower the pallet together with the swing arm is required.

The present invention has been made in view of the above circumstances. An object of the present invention is to automatically move a pallet in a horizontal direction without using a special mechanism for raising and lowering a revolving arm. It is an object of the present invention to provide a pallet changing device capable of raising and lowering a pallet and shortening the pallet changing time.

[0006]

In order to achieve the above object, in the pallet exchanging device according to the first aspect, processing is performed on both sides of a turning center of a pair of left and right turning arms rotatably provided in a horizontal plane. A pallet revolving mechanism that reciprocates the positions of both pallets by revolving the revolving arm by supporting the pallet on which the finished work is placed and the pallet on which the work to be processed is placed, and the spindle of the machine tool. Pallet exchanging device including a pallet moving mechanism for moving the pallet on which the work is placed on the working table together with the pallet moving mechanism between the working position facing the pallet rotating mechanism and the working position facing the pallet rotating mechanism. A guided portion is provided at a position facing the left and right swivel arms on one of the pallet and the swivel arm. When the pallet is moved from the end side of the turning arm to the turning center side by guiding the guided portion to the other of the rotating table and the turning arm, the pallet is lifted to move the pallet against the machining table. There is provided a stepped rail for lowering the pallet to reach the clamp position when the pallet is moved to the end position from the turning center of the turning arm. Characterize.

In the pallet exchanging device according to claim 2,
The pallet changing device according to claim 1, wherein the guided portion is a roller provided at four corners of the pallet.

In the pallet exchanging device according to claim 3,
3. The pallet changing device according to claim 2, wherein the stepped rail is provided with a rear side step portion that engages with a roller closer to a turning center of the turning arm of the pallet, and a turning center of the turning arm of the pallet. Two step portions are formed, a front side step portion that engages with a distant roller, and these step portions have a back side step portion corresponding to the rollers provided at different heights of the pallet. It is characterized in that it is set higher than the front step.

In the pallet exchanging device according to claim 4,
2. The pallet changing device according to claim 1, wherein the guided portion is a roller provided inside and outside of the pallet, and the stepped rail is provided on the turning arm, the inner roller and the outer roller. It is characterized in that two rows of inner stepped rails and outer stepped rails are provided so as to correspond to the above.

In the pallet exchanging device according to claim 5,
The pallet changing device according to any one of claims 1 to 4, wherein the pallet moving mechanism is provided on the machining table in a standing state, and the pallet is provided on the pallet, and the pallet moving mechanism is vertically opposed to the drive pin. And a hook having a groove engaged with the drive pin so as to be restrained so as to be movable and relatively immovable in the movement direction of the processing table.

In the pallet exchanging device according to claim 6,
The pallet exchanging device according to claim 5, wherein the pallet rotating mechanism is arranged concentrically with the center of rotation of the rotating arm and has an arc-shaped guide that engages with the groove of the hook when the pallet rotates. A rail is provided, and the guide rail is provided with a notch through which the hook enters.

According to the present invention, when the pallet is moved together with the machining table from the end side of the revolving arm to the revolving center side, the guided portion of the pallet is guided along the stepped rail, so that the pallet is It will rise automatically. On the contrary, when the pallet is moved from the turning center of the turning arm to the end side, the guided portion of the pallet is guided along the stepped rail, so that the pallet is automatically lowered. That is, by using the stepped rail, it is possible to automatically move up and down when moving the pallet in the horizontal direction without using a special lifting mechanism.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a machining center equipped with a pallet changing device according to the present invention, in which reference numeral 1 is a base. This base 1 has a fixed column 2
The main shaft 3 is moved up and down on the fixed column 2 by the X-axis feed servomotor 4 and the saddle S is moved up and down on the fixed column 2 by the Y-axis feed servomotor 5. It is mounted movably in the X and Y axis directions via a spindle head H that moves in the direction (Y direction).

7 is a tool storage device for automatic tool change (ATC
Magazine). A plurality of tools are arranged inside the tool storage device 7 for automatic tool change, and the most suitable tool for the current machining is selected from the tools, and the automatic tool changer (ATC chain) 8 automatically moves the tool to the tip of the spindle 3. It can be attached. Further, 9 is a high-voltage panel, 10 is a splash guard, 11 is a swivel arm 21 described later,
It is a revolving panel that is integrally inverted with 21.

In this machining center, a work mounted on the pallet P is subjected to a predetermined machining while using a tool mounted on the spindle 3, but when the machining is completed, the pallet P on which the machined work is placed. And the pallet P on which the work to be processed is placed
Are automatically replaced by the pallet changing device 20 according to the present invention.

The pallet changing device 20 has a pair of left and right turning arms 21 and 21 rotatably provided in a horizontal plane.
With the pallet P on which the processed work is placed on both sides of the turning center of the pallet and the pallet P on which the work to be processed is placed, respectively, the turning arms 21 and 21 are turned to move the pallet. A pallet P on which a work is placed is processed between a pallet rotating mechanism 22 for exchanging the position of P, a machining position (a) facing the spindle 3 and a changing position (b) facing the pallet rotating mechanism 22. And a pallet moving mechanism 24 for moving the machining table 23 together with the pallet moving mechanism 24. The processing table 23 is arranged on the upper surface of the base protruding portion 1A extending toward the main spindle 3 side of the base 1 so as to be reciprocally movable along the main spindle 3 direction (Z direction) (see FIGS. 3 and 4).

The pallet turning mechanism 22 will be described. As shown in FIGS. 2, 3, 5, and 6, the pallet changing device main body 30 arranged on the axial extension of the base protruding portion 1A has a bearing 31. , 31, a pivot arm central shaft 32 is rotatably provided along a horizontal plane, and an upper end of the pivot arm central shaft 32 is provided with an arm mounting portion 32a projecting to both sides, and the arm mounting portion 32a.
The pair of left and right revolving arms 21, 21 are attached so as to integrally revolve in a parallel state.

Further, a pinion gear 34 is attached to the outer periphery of the lower end of the pivot arm central shaft 32 so as to rotate integrally with a rotation stop key 34a. Pinion gear 3
A rack 35 is meshed with the rack 4, and one end of the rack 35 is connected to the cylinder 36. And the cylinder 36
Is expanded and contracted by switching the switching valve 36aa of the hydraulic mechanism 36a which is the drive source, whereby the rack 35 is moved along the axial direction, whereby the pinion gear 34
The pivot arm central shaft 32 and the pivot arms 21, 21 integrally attached to the pivot arm central shaft 32 are pivotally operated around the pivot center (C).

A stepped rail 37 is attached to the upper part of the revolving arm 21. Stepped rail 37
Is to guide the rollers Pa and Pb, which are guided portions, which are rotatably provided at both left and right sides of the pallet P and at both end sides in the Z-axis direction, that is, at four corners of the pallet. As the guided portion, instead of the rollers Pa and Pb, a cylindrical pin in which a sliding member having a small friction coefficient is fixed on the sliding contact side with the stepped rail 37, or another rod-shaped member can be used. Specifically, when the pallet P is moved from the tip end side of the turning arm 21 to the turning center (c) side (base end side), the stepped rail 37 raises the pallet P to the working table 23. On the other hand, the pallet P is moved to the unclamped position (height), and conversely, the pallet P is moved to the rotation center (C) of the rotation arm 21.
When the pallet P is moved from the to the tip side, the pallet P is guided by the step portions 37a and 37b described later so that the pallet P is lowered to reach the clamp position (height) with respect to the working table 23.

The stepped rail 37 has a rear side step portion 37a which engages with the roller Pa closer to the turning center (c) of the turning arm 21 of the pallet P and the turning arm 21 of the pallet P at the time of guiding. Roller Pb farther from the center of rotation (C)
Front step 37b that engages with the front side step 37a is formed.
It is set at a position higher than b. On the other hand, pallet P
The rollers Pa, Pa, Pb, Pb provided at the four corners of
Corresponding to the shape of the stepped rail 37, the back side step portion 3
The roller Pa engaged with 7a is high, and the roller Pb engaged with the front step 37b is low.

The distance l ₁ between the rollers Pa and Pb and the distance L ₂ between the steps 37a and 37b are set to the same value. Further, the rear side step portion 37a and the front side step portion 37b of the stepped rail 37 are inclined surfaces with a high proximal end side and a low distal end side of the revolving arm 21 so that the rollers Pa and Pb can be quickly guided in the vertical direction, respectively. It is said that. The portion connecting the two step portions 37a and 37b and the portion extending from the rear side step portion 37a to the base end side of the revolving arm 21 are horizontal flat portions 37c and 37d, respectively.

Further, the pallet P has a pair of revolving arms 2
When the pallet P is moved between No. 1 and No. 21, the roller Pa set to a high level on the pallet P moves to both step portions 37a, 3a of the stepped rail 37.
7b and runs on the flat portion 37c to reach the back side step portion 37a, the roller Pb of the pallet P set low is brought into contact with the front side step portion 37b from the free state, and each roller Pa, Pb moves on each of the step portions 37a and 37b to reach the flat portions 37c and 37d, respectively, and the pallet P is raised while keeping the horizontal state (see FIG. 4).

The pallet rotating mechanism 22 is provided with pallet shift preventing means 39 so that the pallet does not shift outward in the radial direction even if the pallet receives a centrifugal force during turning. That is, as shown in FIG. 2, FIG. 3, and FIG. 6, the pallet shift prevention means 39 is in a state where the arc-shaped guide rail 40 is arranged concentrically with the turning center (c) in the pallet exchanging device body 30. The hook 4 fixed and attached to the guide rail 40 on one end surface side of the pallet P in a protruding state
The circular arc groove 41a on the lower surface of No. 1 is engaged.
The curvature of the arc groove 41a is set to be approximately the same as the curvature of the guide rail 40. Further, a notch 42 for allowing the hook 41 to enter is provided at a position of the guide rail 40 along the central axis of the pallet changing device body 30 (see FIG. 3).

On the other hand, in the pallet moving mechanism 24, the machining table 23 has a machining position (a) and an exchange position (b) by a Z-axis feed servomotor 45 and a screw mechanism (not shown) connected thereto. Between the main shaft 3 of the machining table 23 and a drive pin 46 in an upright state. The hook of the hook 41 of the pallet P is formed at the tip of the drive pin 46. The groove 41a is configured so as to be relatively movable in the vertical direction and immovable in the moving direction (Z-axis direction) of the processing table so as to be restrained.

The pallet P is firmly positioned and fixed on the upper surface of the processing table 23 by a positioning clamp mechanism 47 described below. As shown in FIG. 6, the positioning clamp mechanism 47 includes a plurality of (four in the present embodiment) cylinders 50 formed on the upper surface of the processing table 23, a positioning cone 51 having a lower portion fitted to the cylinders 50, and screws. It is fixed. A plurality of balls 52 are radially movably accommodated in a plurality of ball accommodating holes formed in the radial direction at appropriate intervals in the circumferential direction at an upper protruding tip of the positioning cone 51. These balls 52 have a ball restricting member 53 inserted vertically into a shaft hole 48 concentrically provided in a positioning cone 51, and a ball 54 of a spring 54 housed in a large diameter hole 49 below the shaft hole 48. When in the lowered position due to the urging force,
Since the position of the upper end inclined surface 53a of the ball restricting member 53 coincides with the position of the ball 52, the inside of the ball accommodating hole of the positioning cone 51 can be moved radially inward, and the cylinder 50 has Pressure oil is introduced into the pressure chamber 55 formed between the bottom portion and the piston 50a integrally provided at the lower end of the ball restricting member 53, and the ball restricting member 53 is in the upper position against the biasing force of the spring 54. At some times, the ball 52 is pushed by the upper end inclined surface 53a of the ball restricting member 53 and is maintained in the outward protruding state from the upper end small diameter portion 51a of the positioning cone 51.

On the other hand, an engaging ring member 57 is attached to the lower surface of the pallet P, and the upper end small diameter portion 51a of the positioning cone 51 is inserted through the center of the engaging ring 57, and the upper end small diameter portion 51a of the engaging cone 57 is inserted. The taper hole 57a, which has a diameter larger than that of the taper hole 57a, is fitted downward, and is engaged with the ball 52 which is located above the taper hole 57a and moves radially outward. A hole 57c having a tapered hole 57b that expands upward is formed.

The positioning clamp mechanism 47 shown in FIG.
When the pallet P is lowered downward in the state shown in FIG. 3, the upper end small diameter portion 51a of the positioning cone 51 of the processing table 23 is inserted into the hole 57c of the engaging ring member 57 of the pallet P, and the upper end small diameter portion Taper shaft portion 51 below 51a
b is fitted into the tapered hole 57a of the engagement ring member 57,
The pallet P is planarly positioned with respect to the processing table 23. Then, in this state, when the pressure oil is introduced into the pressure chamber 55 and the ball restricting member 53 moves to the upper position, the ball 52 is projected in the radial direction so as to project outward from the upper end small diameter portion 51b of the positioning cone 51. The ball 52 is pushed outward and the ball 52 is firmly engaged with the inner surface of the tapered hole 57b of the engagement ring member 57, so that the engagement ring member 57
And the positioning cone 51 are integrally connected. As a result, the pallet P is firmly clamped while being accurately positioned on the processing table 23.

After that, in order to release the clamp by the positioning clamp mechanism 47, the pressure oil is removed from the pressure chamber 55, and the ball restricting member 53 is moved to the lowered position by the urging force of the spring 54. At this time, the ball 52 is in a state of facing the upper end inclined surface 53a of the ball restricting member 53 and being movable inward in the radial direction of the positioning cone 51. Therefore, when the pallet P is raised in this state, the engagement ring The ball 52 is moved inward by the taper hole 57b of the member 57, the upper end small diameter portion 51a of the positioning cone 51 is disengaged from the hole 57c of the engaging ring member 57, and the positioning and clamping are released. In addition,
Reference numeral 58 in FIG. 7 is a telescopic cover.

Next, the operation of the pallet changing device having the above structure will be described. At the processing position (a), when the predetermined processing by the machine tool on the workpiece placed on the pallet P is completed, the clamping by the positioning clamp mechanism 47 is first released. That is, the pressure oil is drained from the pressure chamber 55 formed between the bottom of the cylinder 50 and the piston 50a of the ball restricting member 53, the ball restricting member 53 is moved to the lowered position, and the engagement ring member 57 by the ball 52 is moved.
The pressure on the taper hole 57b is released.

Next, the pallet moving mechanism 24 moves the pallet P from the processing position (a) facing the spindle 3 to the exchange position (b) facing the pallet turning mechanism 22 (see FIG. 4). Specifically, the Z-axis feed servomotor 45
To operate the machining table 2 via a screw mechanism (not shown).
3 is moved to the exchange position (b) direction. At this time, the drive pin 46 also moves integrally with the processing table 23, and the hook 41 engaged through the arcuate groove 41a engaging the tip of the drive pin 46 and the pallet P to which the hook 41 is attached are also processed. It moves integrally with the table 23 in the exchange position (b) direction.

When the pallet P approaches the exchange position (b), the rollers Pa, Pb of the pallet P are moved by the revolving arm 21,
Step on the stepped rails 37, 37 on the 21. The stepped rails 37, 37 are formed with a back side step portion 37a and a front side step portion 37b, respectively, and these step portions 37a, 37b.
The four rollers Pa and Pb run on each other simultaneously. At this time, the pallet P is lifted by the height L of the step while being kept in the horizontal state (see FIG. 4). Then, when the pallet P reaches the movement end position in the Z-axis direction, that is, the exchange position (b), the pallet P is separated from the machining table 23 and completely transferred onto the flat portions 37c and 37d of the turning arms 21 and 21. .

When moving the pallet P, the arcuate groove 41a of the hook is not
Since they are relatively movable in the vertical direction and relatively immovable in the Z-axis direction and are engaged so as to be restrained, the pallet P moves up and the positioning cone 5 of the processing table 23 is moved.
Even in the state in which the pallet P is released from 1, there is no problem in ensuring the movement of the pallet P in the Z-axis direction following the processing table 23 and stopping the positioning of the pallet P at the exchange position (B).

When the pallet P reaches the exchange position (B) in the Z-axis direction, the tip end side of the hook 41 enters the inside of the guide rail 40 through the notch 42 of the guide rail 40, and at this time, the drive pin 46. Is located on the circle drawn by the guide rail 40, and the arcuate groove 41a of the hook 41 is also located on the circle drawn by the guide rail 40 (see FIG. 3).

In this state, the cylinder 36 of the pallet revolving mechanism 22 is extended to move the revolving arms 21, 21 to 18 through the rack 35 and the pinion gear 34 meshing with the rack 35.
Turn 0 degrees. A pallet P on which a workpiece to be machined is to be machined is previously mounted on the upper surface of the revolving arm 21 on the side opposite to the spindle 3, and the pallet P is machined by revolving the revolving arms 21, 21 as described above. The pallet P on which the finished work is placed and the pallet P on which the work to be processed is placed are exchanged.

At the time of the turning, the pallet P receives a centrifugal force and tries to shift outward, but at this time, since the pallet shift preventing means 39 operates, the pallet P does not shift outward. That is, the arcuate groove 41a formed on the lower surface of the hook 41 of the pallet P is engaged with the guide rail 40 to prevent the pallet P from being displaced outward during turning.

When the pallet P is positioned on the processing table 23 after the pallet is exchanged, the hook 41 of the pallet P corresponds to the notch 42 of the guide rail 40, and the hook 41 has a diameter defined by the guide rail 40. At the same time, the hook 41 engages with the drive pin 46 on the machining table 23 side and is restrained to prevent relative movement in the Z-axis direction from the drive pin 46.

After that, the pallet P on which the work to be processed is placed by the pallet moving mechanism 24.
To the processing table 23. That is, the Z-axis feed servomotor 45 is operated to move the machining table 23 from the exchange position (B) to the machining position (A) via a screw mechanism (not shown). At this time, the drive pin 46 also moves integrally with the processing table 23, and the pallet P is moved to the processing table 2 via the hook 41 that engages with the tip of the drive pin 46.
Move together with 3.

When the pallet P moves away from the exchange position (b), the rollers Pa and Pb of the pallet P are moved to the stepped rail 3
The pallet P descends when passing through the stepped portions 37a and 37b of the pallets 7 and 37, and the engagement ring member 5 on the lower surface of the pallet P
The small diameter portion of the tip of the positioning cone of the processing table fits into the hole 57a of No. 7.

After that, when the pallet P reaches the processing position (a), the positioning clamp mechanism 47 is operated.
That is, when pressure oil is introduced into the pressure chamber 55 to raise the ball restricting member 53, the ball 52 is pressed into the tapered hole 57b of the engaging ring member 57 by the upper end inclined surface 53a thereof, whereby the engaging ring member 57. Is pressed downwards,
The taper hole 57a is the taper shaft portion 5 of the positioning cone 51.
The pallet P is clamped on the working table by being firmly fitted to the 1b. In this state, the work fixed on the pallet P is processed. Hereinafter, by repeating the above operation, the work can be automatically exchanged and processed.

According to the pallet exchanging device 20 described above, when the pallet P is moved together with the processing table 23 from the tip end side of the revolving arm 21 to the revolving center side, the roller Pa of the pallet P is moved along the stepped rail 37. , Pb to automatically raise the pallet P, and
On the contrary, when the pallet P is moved from the turning center of the turning arm 21 to the end side, the rollers Pa and Pb of the pallet P are guided along the stepped rail 37, so that the pallet P is automatically lowered. . That is, the stepped rail 37
By using, it is possible to move the pallet P in the horizontal direction and simultaneously move it up and down without using a special lifting mechanism.

In the above embodiment, the swivel arms 21, 21 are swung by 180 degrees in order to exchange the pallet P, but it is not always necessary to swivel by 180 degrees and may be 90 degrees or 120 degrees.

In the above embodiment, the swivel arm 2 is used.
A combination of a cylinder 36, a rack 35, and a pinion gear 34 is used to rotate the wheels 1 and 21.
The present invention is not limited to this, and a configuration may be adopted in which the revolving arms 21, 21 are revolved by using a servo motor.

Further, in the above embodiment, the positioning and clamping mechanism 47 can perform positioning and clamping at the coaxial center position and does not cause deformation of the pallet due to the above clamping force, which is a preferable mode. Alternatively, it may be configured as shown in FIG. That is, FIG.
The positioning clamp mechanism 60 shown in (1) comprises a pressing means 61 for pressing the pallet P toward the working table side, and a positioning means 62 for planarly positioning the pallet P with respect to the working table 23.

The pressing means 61 is provided with a clamp claw 61a which is vertically movable so as to project from the upper surface of the processing table 23, and an engaging groove 61b which is engaged with the clamp claw 61a is provided on the pallet P side. The claw 61a is the engaging groove 6
It is adapted to be pressed downward by hydraulic pressure while being engaged with 1b. Here, the engaging groove 61b and the clamp claw 6
The clearance C between the stepped rail 37 and the stepped rail 37 is set to be slightly larger than the step difference between the stepped portions 37a and 37b. The positioning means 62 is provided in the taper hole of the engagement ring member 63 attached to the pallet P in the processing table 23.
The structure is such that the taper pin 64 provided at the above is fitted.

In the above embodiment, the rollers are provided on the pallet P side and the stepped rails are provided on the revolving arm 21 side, but the present invention is not limited to this, and the rollers Pa and Pb of the pallet P and the revolving arm are provided. 21 steps 37a, 37
It is also possible to reverse the relationship with b, that is, to provide the stepped rail 37 having step portions 37a and 37b on the lower surface on the pallet P side, and to attach the rollers Pa and Pb to the revolving arm 21 side.

Further, as shown in FIG. 9, two swivel rails 66, 67 are provided on each of the swivel arms 21, 21 with stepped portions 65, 65 having the same inclined surface at the tips thereof.
And the rollers Pb and Pc of the pallet P are mounted at the same height position, the front end roller Pb is guided by the inner stepped rail 66, and the base end side roller Pc is protruded to the outer side, The rail 67 may be guided. In this case, the length of the outer stepped rail 67 is made to match the mounting distance la of the rollers Pb and Pc,
The horizontal portions 66a and 67a of the stepped rails 66 and 67 have the same height. Even with this configuration, the pallet P
Can be raised and lowered while maintaining a horizontal state.

[0047]

According to the pallet exchanging device according to the first aspect of the present invention, the pallet can be automatically moved up and down when the pallet is moved in the horizontal direction without using a special mechanism for moving up and down the swing arm. Moreover, since the step of raising and lowering the pallet can be omitted, the pallet replacement time can be shortened.

According to the pallet exchanging device of the second aspect, since the guided portion is constituted by the rollers, the smooth movement of the pallet can be guided.

According to the pallet exchanging device according to the third aspect of the present invention, the back side step portion of the stepped rail is set higher than the front side step portion in correspondence with the roller height of the pallet.
It is possible to raise and lower the pallet while keeping it horizontal.

According to the pallet exchanging device of the fourth aspect, the pallet is provided with rollers arranged inside and outside, respectively, and the turning arm is provided with inner and outer rollers so as to correspond to the inner roller and the outer roller, respectively. Since the two stepped rails are provided, the height of the rollers provided on the pallet can be set to the same height position, and the number of stepped portions provided on the stepped rail may be one. In addition, the stepped rail structure can be simplified.

According to the pallet exchanging device of the fifth aspect, the pallet can be moved integrally with the processing table even when the distance between the pallet and the processing table below is changed.

According to the pallet exchanging device of the sixth aspect, it is possible to prevent the pallet from being displaced outward in the radial direction due to a centrifugal force when the pallet is swung and exchanged.

[Brief description of drawings]

FIG. 1 is a machining center including a pallet changing device according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a main part of the pallet changing device according to the embodiment of the present invention.

FIG. 3 is a plan view showing a main part of the pallet changing device according to the embodiment of the present invention.

FIG. 4 is a side view showing a main part of the pallet changing device according to the embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a main part of the pallet changing device according to the embodiment of the present invention.

FIG. 6 is an enlarged cross-sectional view showing a main part of the pallet changing device according to the embodiment of the present invention.

7 is a sectional view taken along line XX of FIG.

FIG. 8 is a cross-sectional view showing the clamp mechanism according to the embodiment of the present invention.

9A is a plan view showing another embodiment of the swivel arm of the present invention, and FIG. 9B is a side view of the same.

[Explanation of symbols]

3 Spindle 20 Pallet Changer 21 Swivel Arm 22 Pallet Swivel Mechanism 23 Machining Table 24 Pallet Moving Mechanism 32 Swivel Arm Central Axis 34 Pinion Gear 35 Rack 36 Cylinder 37 Stepped Rail 37a Back Side Step 37b Front Side Step 37c Flat Section 39 Pallet Displacement prevention means 40 Guide rail 41 Hook 41a Arc groove 42 Notch 45 Z-axis feed servo motor 46 Drive pin 47 Clamp mechanism P Pallet Pa, Pb, Pc Roller

Claims (6)

(57) [Claims] 1. A pallet (P) on which a machined work is placed on both sides of the center of rotation of a pair of left and right revolving arms (21, 21) rotatably provided in a horizontal plane, and a pallet (P) to be machined. A pallet turning mechanism (22) for supporting a pallet (P) on which a work is placed and turning the turning arm to exchange the positions of both pallets, and a machining position (a) facing a spindle of a machine tool. A pallet moving mechanism (24) for moving the pallet on which the work is placed on the working table (23) together with the working table (23) between the pallet turning mechanism and the exchange position (b). A pallet exchanging device (20), wherein one of the pallet and the swivel arm (21) is provided with a guided portion (Pa, Pa) at a position facing the left and right swivel arms.
Pb) is provided, and the other of the pallet and the swing arm (21) is
When guiding the guided portion to move the pallet from the end side of the turning arm to the turning center side, the pallet is raised to reach the non-clamping position with respect to the processing table, and conversely the pallet is turned. Of the stepped rail (3) for lowering the pallet to move it to the clamp position with respect to the machining table when moving from the turning center to the end side.
7) The pallet exchanging device is provided. 2. The pallet changing device according to claim 1, wherein the guided portions (Pa, Pb) are rollers provided at four corners of the pallet. 3. The stepped rail (27) includes a rear step portion (37a) engaging with a roller closer to a turning center of the turning arm of the pallet, and a turning center of the turning arm of the pallet. To the front side step (3
7b) and two step portions are formed, and these step portions are set so that the back side step portion is higher than the front side step portion in correspondence with the rollers provided with different heights of the pallet. The pallet exchanging device according to claim 2, wherein: 4. The guided portion (Pa, Pb) is a roller (P) provided inside and outside the pallet.
b, Pc), wherein the stepped rail (27) corresponds to the swivel arm with the inner roller and the outer roller, respectively, and an inner stepped rail (66) and an outer stepped rail (67). 2. The pallet exchanging device according to claim 1, wherein the pallet exchanging device is provided in two. 5. The pallet moving mechanism is provided on the working table in a standing state and a drive pin (46), which is provided on the pallet, and is movable relative to the drive pin in the vertical direction and of the working table. A hook (41) having a groove (41a) to be engaged with the drive pin so as to be relatively immovable in the moving direction and to be restrained, and a hook (41). The pallet changer described. 6. The pallet turning mechanism has an arcuate shape which is arranged concentrically with a turning center of the turning arm and engages with a groove (41a) of the hook (41) when the pallet turns. A guide rail (40) is provided, and the guide rail has a notch (42) through which the hook enters.
6. The pallet changing device according to claim 5, further comprising: