JPH0440138B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a table transfer device used, for example, in machine tools. (Prior art) In a conventional table transfer device, a movable table is slidably attached to a fixed bed, and the feeding mechanism of this movable table is composed of a ball screw and a rotating motor such as a servo motor or a stepping motor that rotates the ball screw. It was common practice to control the linear motion of a movable table using the rotational motion of a ball screw for highly accurate positioning. However, due to ball screw backlash, etc., the responsiveness during starting and stopping is poor, making it impossible to achieve high positioning accuracy.Also, if the pitch of the ball screw is made smaller in order to achieve Sakai accuracy, the high speed will be poor, and the ball screw and rotary motor There were drawbacks such as the need to assemble the equipment, which increased the size of the device. On the other hand, when using a linear motor,
Since there is no need for a mechanical drive transmission mechanism such as a ball screw, it has good responsiveness and can be driven at high speed, and the movable element and stator of the linear motor can be incorporated between the movable table and the fixed bed. Various table transfer devices using linear motors have been proposed, which have advantages such as being able to be made smaller and more compact. (Problem to be Solved by the Invention) However, in the case of such a conventional example, the stator is usually fixed to the fixed bed side and the movable table moves above it, so the movable range of the movable table is It was limited to the length of the stator. Therefore, when moving a long distance, it was necessary to manufacture a long stator. On the other hand, the stator teeth of the stator are formed by etching a steel plate or the like, but the longer the stator, the longer the etching bath is required, which leads to an increase in production equipment and costs. Furthermore, there is a problem in that the manufacturing cost of the stator itself increases in proportion to its length. In order to solve this problem, it is possible to form a long stator by joining together several short stators, but the joint part of each stator must be made with the same precision as the pitch of the stator teeth. It is difficult to add joints, and even if the table is running at a pitch of 1 mm, the pitch may be over or under 1.5 mm at the joint, resulting in poor running accuracy of the movable table. Furthermore, there was a problem in that the feed pitch varied depending on the accuracy of the stator teeth. The present invention has been made to solve the above problems, and its purpose is to be able to move infinitely and precisely even over a long distance, regardless of the length of the stator. An object of the present invention is to provide a transportable table transfer device. (Means for Solving the Problems) In order to achieve the above object, the present invention provides a first movable table and a second movable table on a fixed bed.
Movable tables are provided spaced apart in the vertical direction, the first movable table and the second movable table are respectively attached via linear bearings so as to be movable in the same direction, and the first movable table and the second movable table have a A brake means is attached to fix the first movable table and the second movable table to the fixed bed, a plurality of linear motors are interposed between the first movable table and the second movable table, and the first movable table The second movable table is alternately fixed to the fixed bed by brake means and moved alternately to enable stepwise movement. (Examples) The present invention will be described below based on illustrated examples. In FIGS. 1 to 6 showing a linear motor according to a first embodiment of the present invention, reference numeral 1 denotes a fixed bed, and flanges 2, 2 at both ends thereof project upward and extend parallel to each other in the longitudinal direction. are formed, and track stands 3, 3 are fixed to the fixed bed 1 in parallel along the inner surfaces of both flanges 2, 2 with fasteners 4 such as bolts. A first movable table 5 is connected to the tracks 3, 3 via linear bearings.
A second movable table 6 is supported movably along the tracks 3, 3. Two sets of linear motors 7 and 8 (linear pulse motors in this embodiment) are interposed between the opposing surfaces of the first movable table 5 and the second movable table 6. The stator 7b and mover 7a of the first linear motor 7, one of the linear motors 7 and 8, are arranged such that the stator 7b is on the first movable table 5 side and the mover 7a is on the second movable table 6 side. The stator 8b and mover 8a of the other second linear motor 8 are arranged as follows.
Contrary to the first linear motor 7, a movable element 8a is disposed on the first movable table 5 side, and a stator 8b is disposed on the second movable table 6 side. 1st and 2nd
The movable tables 5, 6 are supported on the tracks 3, 3 by four pairs of linear bearings 9, 10, respectively. In other words, taking the second movable table 6 as an example, two pairs of linear bearings 9 are attached to both sides of the movable element 7a of the first linear motor 7 attached to the underside of the table, and fixing devices 11 such as bolts are attached to the second movable table 6.
Two pairs of linear bearings 9, . . . are fixed on both sides of the stator 8b of the second linear motor 8.
are fixed by fixing tools 11... Further, electromagnetic brakes 12, 12 as a pair of braking means are fixed between the linear bearings 9, 9, and also between the linear bearings 9, 9 on both sides of the center part of the stator 8b of the second linear motor 8. A pair of electromagnetic brakes 12, 12 are fixed to the.
The first movable table 5 also has the same configuration as the second movable table 6, and has four pairs of linear bearings 1.
0,... and two pairs of electromagnetic brakes 12,... are attached. On the other hand, ball rolling grooves 3a are formed in two upper and lower positions in the track bases 3, 3, in which the linear bearings 9, 10 attached to the first movable table 5 and the second movable table 6 are guided. The first movable table 5 moves along the lower ball rolling grooves 3a via linear bearings 10, and the second movable table 6 moves along the upper ball rolling grooves 3a.
along... via linear bearings 9.... Each of the first and second movable tables 5, 6 is fixed to the fixed bed 1 by electromagnetic brakes 12, . . . , and these electromagnetic brakes 12, . It consists of a brake shoe 13 that is pressed against the track base 3, a plunger 14 that moves the brake shoe 13 back and forth in a direction perpendicular to the track base 3, and an electromagnetic coil 15 that operates the plunger 14. When energized, the plunger 14 is attracted and the brake shoe 13 is separated from the track base 3, and when the power is not energized, the brake shoe 13 is pressed against the track base by the spring 16. Each linear bearing 9, 10 is shown in FIG.
As shown in Figure 0, there are two ball rolling grooves on one side.
7, 17 are provided, and a ball escape hole 1 is provided inside.
Bearing block 19 provided with 8 and 18
and a retainer 20 that holds two rows of load balls.
, ball rolling grooves 17, 17 and ball escape hole 1
8, 18, and a pair of side lids 21, 21 communicating with each other. The load balls 22, 22... are provided with ball rolling grooves 17, 17 and ball relief holes 18,
It is designed to cycle between 18 and 18. The contact angle α between the ball rolling grooves 17, 17 and the load balls 22, 22... is approximately 45 degrees, but is not limited to 45 degrees and may be in the range of 30 to 60 degrees.
Further, the gaps between the linear bearings 9, . . . 10, . That is, by tightening the clearance adjustment bolts 23, the linear bearings 9,..., 10,...
At the same time, the reaction force of the pressing force of the clearance adjustment bolts 23, . . . acts on the linear bearing 9 on the opposite side, and a preload is applied to the load balls 22 . As a method for applying preload, an eccentric pin, a taper gib, etc. may also be used. Next, FIG. 11 shows the first
The main parts of the linear motor 7 are shown, and the mover 7
For example, a has a structure in which a permanent magnet 24 is interposed in the center, and two magnetic cores 25 and 26 are arranged facing each other on the left and right sides of the permanent magnet 24, and one of the magnetic cores 25 is magnetized to the N pole by the permanent magnet 24 first magnetic pole 2
7 and a second magnetic pole 28 are formed, and the other magnetic core 26 is formed with a third magnetic pole 29 and a fourth magnetic pole 30 that are magnetized to the S pole by the permanent magnet 24. As shown in FIG. 11, the stator 7b is provided with fixed teeth 7b' having a U-shaped cross section extending in a direction substantially perpendicular to the longitudinal direction, and are provided at equal intervals at the same pitch P over substantially the entire length in the longitudinal direction. ing. Each magnetic pole 27-3
0 also has magnetic pole teeth 27a of the same pitch as the stator 7b.
~30a are formed respectively. First magnetic pole 27 and second magnetic pole 28 on the N pole side
includes a first coil 31 and a second coil 32.
are wound and connected in series so that magnetic flux is generated in opposite directions when current flows.
It is electrically connected to a pulse generation source (not shown). On the other hand, a third magnetic pole 29 and a fourth magnetic pole 30 on the S pole side are also wound with a third coil 33 and a fourth coil 34, which are similarly connected in series. )It is connected to the. Here, for convenience of explanation, for example, the first magnetic pole 2
The phase of the magnetic pole tooth 28a of the second magnetic pole 28 is shifted by 1/2 pitch (1/2P) with respect to the magnetic pole tooth 27a of the third magnetic pole 29. It is assumed that the phases of the magnetic poles 30a are similarly shifted by 1/2 pitch (1/2P). Further, a first magnetic pole 27 and a second magnetic pole 28 on the N pole side
The magnetic pole teeth 29a of the third magnetic pole 29 and the fourth magnetic pole 30 on the S pole side with respect to the magnetic pole teeth 27a, 28a of
30a is assumed to be out of phase by 1/4 pitch (1/4P). Here, the operating principle of the linear pulse motor of this embodiment will be explained. 12a to 12d show schematic diagrams showing the working principle of the linear pulse motor, in which the first coil 31 and the second coil 32 are connected to the terminal a, and the third coil 33 and the fourth coil are connected to the terminal a. coil 34
A pulse is input from terminal b to the terminal b. In FIG. 12a, the first magnetic pole 27 is connected to terminal a.
(mode) in the direction of exciting the fourth magnetic pole 30 at terminal b in FIG. 12b, and the second magnetic pole 28 at terminal a in FIG.
FIG. 12d shows a state in which a pulse is input to terminal b in a direction to excite the third magnetic pole 29 (mode), and in a direction to excite the third magnetic pole 29 to terminal b (mode). Here, Table 1 shows the magnetic force generation state of each magnetic pole in each mode.

[Table] As shown in Table 1, in the mode, the magnetic force of the first magnetic pole 27 on the N pole side is strong, and the first magnetic pole 27
The movable element 7a is held in a stable state by the suction force between the movable element 7 and the fixed teeth 7b' of the stator 7b. On the other hand, S
The third and fourth magnetic poles 29 and 30 on the pole side are each shifted in phase by 1/4 pitch with respect to the fixed teeth 7b' of the stator 7b. In mode the first magnetic pole 2
The magnetic force caused by the coil 31 of 7 disappears and is replaced by S
As the magnetic force of the fourth magnetic pole 30 on the pole side becomes stronger, the movable element 7a moves relatively in the direction in which the fourth magnetic pole 30 matches the fixed tooth 7b' of the stator 7b in phase.
You will advance by 4 pitches (1/4P). At this time, the first and second magnetic poles 27 and 28 on the N pole side are 1/4
The phase is shifted by a pitch (1/4P). Furthermore, in the mode, the magnetic force of the second magnetic pole 28 on the N pole side becomes strong, and the second magnetic pole 28
The movable element 7a moves in a direction that matches the fixed tooth 7b' in phase.
moves relatively and advances by 1/4 pitch (1/4P), and S
The third and fourth magnetic poles 29 and 30 on the pole side are out of phase by 1/4 pitch (1/4P). In the mode, the magnetic force of the third magnetic pole 29 on the S-pole side becomes strong, and the mover 7a moves relatively in the direction where the third magnetic pole 29 matches the fixed tooth 7b' of the stator 7b in phase.
Advance 4 pitches (1/4P). Further, the mode returns again, and the magnetic force of the first magnetic pole 27 on the north pole side becomes strong, and the movable element 6 moves relatively by 1/4 pitch (1/4P) to reach the state shown in FIG. 12a. In this way, by resetting the mode, the movement is made by 1/4 pitch (1/4P) per pulse. In the above explanation, one-phase excitation was explained, but
It may be driven by two-phase excitation, in which two-phase currents are constantly flowing, or 1-2, in which current is passed alternately in one phase and two phases.
A phase excitation method may also be used. The linear motor having such a configuration is driven as follows. First, the electromagnetic brakes 12, . With the movable table 6 in a free state relative to the tracks 3, 3, pulses are input to each of the movers 7a, 8a of the first and second linear motors 7, 8, as shown in FIGS. 13a, b, and c. The second movable table 6 is driven forward by a predetermined amount (to the left in the figure). In this case, the mover 7 of the first linear motor 7
a moves forward with respect to the stator 7b, but since the second linear motor 8 moves the stator 8b, the stator 8a attached to the first movable table 5 fixed to the track base 3 has a stator. A pulse is input in the direction of retreating from 8b (to the right in the figure),
As a reaction, the stator 8b is moved. Next, after the second movable table 6 moves forward a predetermined amount and stops, the electromagnetic brake 12 of the second movable table 6 is turned off, the second movable table 6 is fixed to the tracks 3, and the first movable table 6 is The electromagnetic brakes 12, . . . of the table 5 are turned on to free the first movable table 5 relative to the tracks 3, 3. Each movable element 7a, 8a of the first and second linear motors 7, 8,
The second movable table 6 with respect to the first movable table 5
Input a pulse in the direction that moves backward (toward the right in the figure). Then, the first movable table 5 moves forward (leftward in the figure) as shown in FIGS. 13c to 13e and stops at a predetermined position. Furthermore, in the state shown in Figure 13e, the first
The electromagnetic brake 12 of the movable table 5 is turned off, the first movable table 5 is fixed to the track base 3, 3, and the electromagnetic brake 12 of the second movable table 6 is turned off.
Turn on... to make the second movable table 6 free, repeat the above operation, and the second movable table 6 and first movable table 5 alternately move forward (to the left in the figure) and move toward the tracks 3, 3. move along infinitely. Since the linear motors are configured in two series in this way, the propulsive force of each movable table 5, 6 is doubled. Furthermore, if there is variation in the feed amount per pulse by each of the first and second linear motors 7 and 8,
For example, if one linear motor advances too much than a predetermined feed amount and the other feed amount lags behind, the error in the feed amount is canceled out. Also, if both of them advance too far beyond the predetermined feed amount, each table 5, 6
The error in the feed amount of the first linear motor 7 can be suppressed to an intermediate error between the two linear motors 7 and 8.
and the second linear motor 8 mutually correct each other, thereby improving the feeding accuracy of each table 5, 6. Furthermore, since the stators 7b, 8b and movers 7a, 8a of the first linear motor 7 and second linear motor 8 are arranged in reverse, the first movable table 5 and the second movable table 6 have the same shape. , one movable table can be used commonly as the first and second movable tables 5 and 6, increasing versatility. In addition, since each of the first and second movable tables 5, 6 is moved via linear bearings 9,..., 10,..., the sliding resistance is small, and even when a large load is applied, the increase in frictional resistance is small. , slides smoothly. In addition, the linear bearings 9,..., of this embodiment
By using 10,..., compared to the case where linear bearings 9,..., 10,... are not used,
It becomes possible to support up to 100 times the load. Furthermore, the contact angle between the load balls 22... of the linear bearings 9,..., 10,... and the ball rolling surface 17... is approximately 45
Since the movable table 5 and the second movable table 5 are made in a degree, the load applied to the first and second movable tables 5 and 6 in four directions, up, down, right and left, can be equally supported. Further, by applying a preload, high rigidity is achieved, so the first movable table 5 and the second movable table
The gap of the movable table 6 is kept constant, stable running performance is obtained, and problems such as pitching, meandering yawing, which causes pitch variations during running, and rolling, which moves while turning from side to side, are prevented. Next, a second embodiment of the present invention is shown in FIGS. 14 to 19, and the same components as in the first embodiment will be described with the same reference numerals.
In this embodiment, the linear motors 7 and 8 have a double configuration as in the first embodiment, but only two ball rolling grooves 17 are provided in the tracks 3 and 3. First, the linear bearings 10, . . . fixed to the first movable table 5 and the linear bearings 9, . . . fixed to the second movable table 6 move along the same ball rolling groove 17.
With this configuration, unlike the first embodiment, the table cannot be shared, but the device can be made thinner by the thickness of the linear bearing. The other configurations and functions are the same as those in the first embodiment, so their explanations will be omitted. In the first and second embodiments described above, the arrangement of the stator and mover of each linear motor is reversed, but two stators are placed on the first movable table side, and two stators are placed on the second movable table side. It is also possible to have a configuration in which two movable elements are provided in the same direction, or the opposite configuration. Further, although an example of two linear motors is shown, three or more linear motors may be installed. Further, although a linear pulse motor driven by a pulse signal is used as the linear motor, a linear induction motor, a linear DC motor, etc. may also be used. (Effects of the Invention) The present invention has the above-described configuration and operation, and the first movable table and the second movable table are each provided with a brake means, and one of the first movable table and the second movable table is selectively operated. Since the stator is fixed to a fixed bed and the first movable table and the second movable table are moved alternately, it is possible to move an infinitely long distance regardless of the length of the stator. Therefore, even when transporting over a long distance, there is no need to manufacture a long stator unlike in the past, making it easier to manufacture the device and reducing costs. Furthermore, there is no pitch deviation between stators that occurs at joints when stators are connected as in the past, and precise feeding is possible. In addition, since linear bearings are used, there is no variation in the table's longitudinal movement (pitching), meandering (yawing), or sideways movement (rolling), resulting in stable and smooth running performance. Furthermore, by arranging multiple linear motors, several times the propulsive force can be obtained, and even if the feed amount of each linear motor varies, the errors in feed amount are reduced by mutually correcting, and the feed accuracy is increased. Various effects can be obtained, such as the ability to

[Brief explanation of drawings]

FIG. 1 is a plan view of a table transfer device according to a first embodiment of the present invention, FIG. 2 is a longitudinal sectional view of the device in FIG. 1, FIG. 3 is a sectional view taken along the - line in FIG. 1, and FIG. is a sectional view taken along - line in Fig. 1, and Fig. 5 is a - line sectional view in Fig. 1.
A line sectional view, FIG. 6 is a - line sectional view of the present invention,
7 is a vertical sectional view of the main part of the electromagnetic brake of the device shown in FIG. 1, FIG. 8 is a front view of the linear bearing of the device shown in FIG. 1, FIG. 9 is a plan view of the device shown in FIG.
Figure 0 is a sectional view taken along the - line in Figure 9, Figure 11 is an enlarged sectional view of the main parts of the mover and stator, and Figures 12a to 12d are schematic front views of the linear pulse motor showing the operating principle of the linear pulse motor. , Figure 13 a to e
14 is a plan view of a table transfer device according to a second embodiment of the present invention, and FIG. 15 is a longitudinal sectional view of the device shown in FIG. 14. , Fig. 16 is - of Fig. 14
17 is a sectional view taken along the - line in FIG. 14, FIG. 18 is a sectional view taken along the - line in FIG. 14, and FIG. 19 is a sectional view taken along the - line in FIG. Explanation of symbols: 1... Fixed bed, 5... First movable table, 6... Second movable table, 7... First linear motor, 8... Second linear motor, 9, 10... Linear bearing, 12... Electromagnetic brake (brake) means).

Claims (1)

[Claims] 1. A first movable table and a second movable table on a fixed bed.
Movable tables are provided spaced apart in the vertical direction, the first movable table and the second movable table are respectively attached via linear bearings so as to be movable in the same direction, and the first movable table and the second movable table have a A brake means is attached to fix the first movable table and the second movable table to the fixed bed, a plurality of linear motors are interposed between the first movable table and the second movable table, and the first movable table and a second movable table which is alternately fixed to the fixed bed by brake means and moved alternately to enable stepwise movement. 2. Two linear motors are interposed between the first movable table and the second movable table, arranged in the moving direction of the first and second movable tables, and one movable element of the linear motor is interposed between the first movable table and the second movable table. 2. The table transfer device according to claim 1, wherein the movable element of the other linear motor is disposed on the second movable table side.