JPS6052902B2 - Conveyance drive device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transfer machine, and more particularly to an improvement in a drive device for conveying a workpiece.

A transfer machine is constructed by combining multiple dedicated machine tools, each in charge of a specific machining process, and a workpiece transfer device that synchronizes the operation of a series of dedicated machine tools and transports workpieces between them. There is.

A common transport method for this type of transport device is an in-line method, in which the workpiece is moved in a linear direction.

Therefore, conventional conveyance drive devices use long hydraulic cylinders to output reciprocating motion, or are configured by combining a constant-velocity electric speed reducer with a complex reciprocating mechanism. However, the workpiece generates vibrations and shocks when driven at high speed due to the transfer characteristics of the above-mentioned transfer device itself. For this reason, there is a limit to increasing the conveyance speed, and for this reason, the time and distance for conveying the workpiece cannot be sufficiently adapted to the increasing speed of dedicated machine tools. As described above, the technical problem in this type of technical field is to make it possible to set the optimum conveyance speed without applying vibration or impact to the workpiece. Therefore, an object of the present invention, in order to solve the above-mentioned technical problems, is to enable easy setting of appropriate conveyance speeds corresponding to conveyance conditions such as various workpiece conveyance times and conveyance distances, and to The aim is to reduce vibrations and shocks as much as possible during transportation.

Based on the above object, the present invention drives a rotary main shaft with a variable speed motor, converts the rotational motion of the rotary main shaft into linear motion by a motion conversion mechanism, and transmits the linear motion to a conveying device. Taking the characteristics into consideration, a cam on the contour curve gate that provides a non-impact speed at each conveyance position is driven, and the output of this cam is used to control the rotational speed of the variable speed motor.

Hereinafter, the present invention will be specifically explained based on an embodiment shown in the drawings. First, as shown in FIG.
, speed command cam 5, detection means 6, and speed control device 7
It is made up of.

The variable speed motor 2 is a DC or AC variable speed motor, and is installed on a frame 10 of a worm reducer 9 as shown in FIG.

The rotation of this variable speed motor 2 is controlled by a torque limiter 14 of a worm shaft 13 via a pulley 11 and a belt 12.
transmitted to. The worm shaft 13 is supported by bearings 15 at both ends of the frame 10,
The worm 16 at the intermediate position is engaged with the worm wheel 17. The worm wheel 17 is fixed to the rotating main shaft 3 by a key 18, and the rotating main shaft 3 is rotatably supported by a bearing 19 to the frame 10. The motion conversion mechanism 4 converts the rotational motion of the rotary main shaft 3 into a reciprocating linear motion and transmits this motion to the conveying device 8. As shown in FIGS. 2 and 3, one end of the rotary main shaft 3 is Attach arm 20 to bolt 21
The two shafts 23 and 24 are attached to this arm 20 so as to be prevented from rotating by means of a key 22, and two shafts 23 and 24 are rotatably attached to this arm 20 using bearings 25 and 26 in a state parallel to the main rotating shaft 3. The gears 27 and 28 that mesh with each other are installed in a state in which they are prevented from rotating by means such as splines, one gear 27 is meshed with a fixed gear 29 fixed to the side surface of the frame 10, and a swing arm 30 is attached to one end of the shaft 24. To the fastening body 31. A slider 3 as a part of the conveying device 8 is mounted on one end of the swing arm 30 so as to be coaxial with the main rotation shaft 3.
The connecting shaft 33 of 2 is rotatably mounted by a bearing 34, so that the slider 32 can slide along a guide bar 35. It is slidably fitted.

Here, the gears 27 and 28, the fixed gear 29, and the arm 20
The swing arm 30 constitutes a Cardan gear mechanism, and serves as means for converting the rotational motion of the rotary main shaft 3 into a linear reciprocating motion and transmitting the linear reciprocating motion to the slider 32 of the conveying device 8. Therefore, the number of teeth of the gear 28 is equal to the number of teeth of the fixed gear 29, and the effective length of the arm 20 is set to be equal to the effective length of the swing arm 30. Note that the arm 20 is attached to the frame 10 by a bearing 36 and a support 37.
It is rotatably held against the Next, the speed command cam 5 is attached, for example, to one end of the rotating main shaft 3, and synchronizes with the movement of the rotating main shaft 3 or the motion conversion mechanism 4 to provide a non-impact speed at each transporting position of the transporting device 8.
For example, it is configured as a plate cam.

The circumferential curve 38 of the speed command cam 5 will be described in detail later. The lift amount of the speed command cam 5 is detected by the detection means 6. As shown in FIG. 3, the detection means 6 is attached to one side of the frame 10, for example, and generates an electric signal to detect the displacement of the dock 39 driven by the speed command cam 5, that is, the lift amount of the speed command cam 5. year. Detect.
That is, the dock 39 is attached to one end of a rod 40, which is slidably held inside a bracket 41, is biased by a spring 42 in a direction approaching the speed command cam 5, and is attached to a roller 43 at one end.
is in contact with the circular curve 38 of the speed command 5. Therefore, when the speed command cam 5 rotates, the dot 39 moves up and down, so the detection means 6 detects its displacement, that is, the lift amount of the speed command cam 5. to generate an electrical detection signal proportional to the circular curve 38 of the speed command cam 5.The detection signal of the detection means 6 is then guided to a known speed control device 7.Here, the speed control device 7 is a servo system. It is comprised of a drive circuit, a speed command voltage setting circuit, etc., and controls the rotational speed of the variable speed motor 2 according to the detection signal.Next, a series of operations of the conveyance drive device 1 will be explained.

The rotation of variable speed motor 2 is transmitted to worm shaft 13 via pulley 11, belt 12 and torque limiter 14. Here, the worm 16 of the worm shaft 13 drives the worm wheel 17 at a constant reduction ratio. Note that the torque limiter 14 cuts off power transmission in the event of overload. Since the rotation of the worm wheel 17 is transmitted to the rotating main shaft 3 by the key 18, the rotating main shaft 3 gives a rotational motion to the arm 20 by its rotation. At this time gear 27
is fixed gear 2 while meshing with fixed gear 29 and gear 28.
Planetary motion around 9. At this time, the rotation of the gear 28 is transmitted to the swing arm 30 via the shaft 24. Here, the tip portion of the swinging arm 30 performs one reciprocating linear motion for each rotation of the rotating main shaft 3, as shown by the imaginary line in FIG. In this way, the slider 32 is guided by the guide bar 35 and repeats one reciprocating linear motion for each rotation of the rotating main shaft 3. The reciprocating linear movement of the slider 32 drives a transfer par (not shown) of the workpiece conveying device 8. On the other hand, the rotating main shaft 3 rotates a speed command cam 5 attached to one end thereof in synchronization with the reciprocating linear movement.

This speed command cam 5 gives the change in the circumferential curve 38 as a vertical change in the dot 39 via the roller 43 and the rod 40. Therefore, the detection means 6 has a detection surface and a dot 3.
9 is detected, and this is converted into an electrical detection signal and sent to the speed control device 7. Here, the speed control device 7 controls the rotation speed (rotation speed) of the variable speed motor 2 to increase or decrease based on the level change of the detection signal.
Now, the relationship between the output (conveyance) characteristics of the motion conversion mechanism 4 and the circumferential curve 38 of the speed command cam 5 will be described in detail.

Today's transfer machines are becoming faster due to mass production.

As transfer machines become faster, there is a demand for shorter workpiece transfer times. For this reason, there is a tendency for transfer speeds to become higher, but with conventional transfer methods, increasing the speed causes shocks and vibrations to be generated in the workpiece during starting, stopping, or movement of the workpiece. Such shocks and vibrations are greatly related to the acceleration curve of the workpiece during movement. The present invention focuses on the above points and is based on an ideal acceleration curve, that is, a motion curve in which acceleration starts from zero, draws a smooth curve halfway, and returns to zero. Examples of such motion curves include cycloid curves and epicycloid curves. The displacement L, velocity V, and acceleration a of the motion of the cycloid curve are expressed by the following formula, where S is the total stroke, 00 is 1800, 0 is the displacement angle of the arm 20, and ω is the rotational angular velocity. These changing characteristics appear as shown in FIG.

On the other hand, when the variable speed motor 2 rotates at a constant speed, the output of the motion conversion mechanism 4 of the Cardan gear mechanism changes its displacement to L.
'', speed V'', acceleration a'', and rotation speed NC
rpm], the following equations are obtained, and their change characteristics are as shown in FIG.

Here, each displacement angle 0 calculated in the case of a cycloid curve
Expression (5) of the velocity V'' in the case of the motion conversion mechanism 4 of the Cardan gear mechanism corresponding to the value of the velocity ■ at the position of
If the number of rotations N of the variable speed motor 2, which is the drive source, is calculated backwards, the number of rotations N can be obtained as follows.

If the value of the rotation speed N obtained by the above equation (7) is set as the rotation speed of the variable speed motor 2 at each stroke position, the output of the motion conversion mechanism 4 by the Cardan gear mechanism operates in a cycloidal curve motion. It turns out.

The rotational speed N in this case is calculated from the above equation (7) as shown in the graph of FIG. The cam diagram (lift H) obtained from this graph of the rotational speed N is as shown in FIG. 7A. And the speed command cam 5 based on this curve
The contour curve 38 has an elliptical cam shape as shown in FIG. 7B. Next, the above-mentioned epicycloid curve will be considered as an example having other transport characteristics.

This epicycloid curve is based on the trajectory of the fixed point P on the planetary circle 45 revolving around the base circle 44, as shown by the broken line in FIG. When the planetary circle 45 revolves around the base circle 44 at a constant speed, a fixed point P on the planetary circle 45
The angle φ formed by the line connecting the center of the base circle 44 and
changes with a certain deviation from the revolution angle 0, and the relationship is expressed by the following equation. ~'Town VVVV
υυriV If the above equation (8) is differentiated with respect to time t, the angular velocity ωo
is calculated, and its angular velocity ω.

is as follows.
ゞDisplacement L″ and velocity V″ expressed here
The movement with acceleration a'' has no impact on the conveying device 8,
It is nothing but something that gives vibration-free motion characteristics. Although the motion converting mechanism 4 in the above embodiment is a Cardan gear mechanism, it is not limited to this and may be any other mechanism.

The motion conversion mechanism 4 in FIGS. 10 to 13 is
This is an application of Ratsell's mechanism, in which the arm 20 is rotated by the rotating main shaft 3, the middle point of a lever 46 with a length twice the effective length of this arm 20 is connected by a pin 47, and the other end is connected to a connecting pin. 48 to the slider 49, and a roller 50 is rotatably attached to one end of the other end, and the roller 50 is guided along a pair of guides 51 and 52 located vertically perpendicular to the guide bar 35. This is an example.

When the rotating main shaft 3 rotates, the arm 20 rotates counterclockwise. In the initial state, the slider 49 moves to the right as shown in FIGS. 10 and 11. In this case, since the roller 50 is guided by the pair of lower guides 52, the slider is reliably displaced to the right. Next, when the arm 20 passes the center line 53 as shown in FIG.
The slider 49 changes its movement in the opposite direction, ie to the left. In this way, the slider 49 is guided by the guide bar 35 and performs a reciprocating linear motion as the main shaft 3 and the arm 20 rotate. Since the motion of this Scott Ratsel mechanism is basically the same as the motion of the Cardan gear mechanism already described, the rotational speed of the variable speed motor 2 is similarly given by the formula (7) already described. This angular velocity ω. A graph showing changes in is shown in FIG. Here, if the rotating main shaft 3 in the motion conversion mechanism 4 of the Cardan gear mechanism is changed by the values of the above equation (9), the outputs of the conveyance drive device 1 are the displacement L'', the speed ■'', and the acceleration a'' are respectively expressed by the following formulas.
Furthermore, this motion conversion mechanism 4 can also be constructed using a reciprocating slider crank mechanism as shown in FIG. 14 or a lever crank mechanism as shown in FIG. 15.

In other words, in the case shown in Fig. 14, the rotation of the main shaft 3 is
0, this is the case where the transmission is transmitted to the slider 55 via the connecting j rod 54, and the one in FIG.
In this case, the rotation of the lever 57 is transmitted to the lever 57 via the connecting rod 56, and its reciprocating motion is transmitted to the slider 58. Further, although the speed command cam 5 is directly attached to the rotating main shaft 3, it may be attached to a part of the motion conversion mechanism 4 and configured in the form of a direct-acting cam. Although the detection means 6 specifically uses an element that detects current loss due to overcurrent, other proximity switches may be used instead. Furthermore, variable-speed rotation can also be obtained by combining a constant-speed motor with a continuously variable transmission, so a variable-speed motor is equivalent to and includes the drive sources of a constant-speed motor and a continuously variable transmission. . The present invention brings about the following unique effects. First, the speed command cam controls the rotational speed (rotation speed) of the variable speed motor and gives the output of the motion conversion mechanism ideal motion conveyance characteristics, so the workpiece can be conveyed without shock or vibration. As a result, the conveyance speed can be increased as much as possible.

Second, if the design of the circular curve of the speed command cam is changed according to the motion characteristics of the interlocking conversion mechanism, ideal conveyance characteristics can be easily obtained for all motion conversion mechanisms, so the conveyance drive system has a high degree of freedom. can be provided.

Thirdly, since the speed command cam always operates in synchronization with the rotating main shaft or the motion conversion mechanism, the desired operation can be reliably achieved.

Fourth, the input and output parts of the control system (speed command cam, detection means, and speed control device) have a simple and general-purpose configuration.
It is easy to put this conveyance drive device into practical use.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the conveyance drive device of the present invention, FIG. 2 is a partially cutaway side view of the variable speed motor and the motion conversion mechanism,
Figure 3 is a vertical sectional view, Figure 4 is a motion characteristic diagram of a cycloid curve, Figure 5 is a motion characteristic diagram of a motion conversion mechanism using a Cardan gear mechanism, Figure 6 is a characteristic diagram of the rotation speed of a variable speed motor, Figures 7A and 7B are displacement diagrams and cam circular curve diagrams of the speed command cam, Figure 8 is a locus diagram of an epicycloid curve, Figure 9 is a characteristic diagram of the angular velocity of the variable speed motor, and Figures 10 to 13. 1 is an explanatory diagram of the operation of the motion conversion mechanism based on the Skott-Ratssel mechanism, and FIGS. 14 and 15 are side views showing other embodiments of the motion conversion mechanism. 1... Conveyance drive device, 2... Variable speed motor, 3...
-Rotating main shaft, 4...Motion conversion mechanism, 5...Speed command cam, 6...Detection means, 7...Speed control device, 8.
...Transportation device.

Claims (1)

[Scope of Claims] 1. A variable speed motor, a rotating main shaft rotationally driven by the variable speed motor, a motion conversion mechanism that converts the rotational motion of the rotating main shaft into linear motion and transmits it to the conveyance device, and this motion conversion A speed command cam for the variable speed motor having a contour curve that synchronizes with the movement of the mechanism and provides a shock-free speed at each transport position of the transport device, a detection means for detecting a lift amount of the speed command cam, and a detection means for detecting the lift amount of the speed command cam; A conveyance drive device comprising: a speed control device for controlling the speed of the variable speed motor according to a signal from the means. 2. The conveyance drive device according to claim 1, wherein the contour curve of the speed command cam is formed so as to impart a cycloidal curve motion to the conveyance device through a motion conversion mechanism. 3. The conveyance drive device according to claim 1, wherein the circumferential curve of the speed command cam is formed so as to impart an epicycloidal curve motion to the conveyance device through a motion conversion mechanism.