JP2794691B2 - Processing machine with camshaft rotation control mechanism - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a processing machine, and more particularly to a plastic working machine equipped with a rotation control mechanism for controlling the rotation of a cam shaft. (Prior Art) Conventionally, in a plastic working machine or the like, a driving method having a slide or a turning portion to which a tool such as a mold or a roll is attached is often based on hydraulic pressure. In the case of a hydraulic servo which is difficult and expensive and complicated, high-precision control is possible, but there are problems due to maintenance (particularly dust) and complexity of the control. As another driving method, there is a method of driving a ball screw directly or via a speed reducer to control the movement of a tool attached to the tip of the ball screw. However, in this method, the ratio (reduction ratio) between the rotational speed of the motor and the moving speed of the tool attached to the ball screw is constant. For this reason, if a high speed can be provided, the load becomes low, and if a high load can be provided, the speed becomes low over the entire stroke. If you try to get a high load at high speed, you need a huge motor. Driving a tool with hydraulic pressure and a ball screw has the above-mentioned problems. Therefore, it is known to use a plastic working machine having a camshaft to perform spinning forming, rolling forming, rotational forming, bending, and the like. Have been. In this type of plastic working machine, when the workpiece to be machined, that is, the object, changes, the movement of a mold or a roll attached to a slide or a turning portion driven by a cam changes, and at that time, They are changing and adjusting the timing. When a cam is used as a drive source for reciprocating or turning a mold or a roll as a processing tool, there are the following advantages. The position, speed and acceleration of the cam follower can be freely determined by selecting the pressure angle of the cam. When the camshaft is driven at a constant rotation speed under a constant torque condition (motor output is constant), if the pressure angle is small, a high load output can be obtained at a low speed. The output of the load is obtained. This is considered to be an ideal function for a plastic working machine because the cam itself has a function as a variable speed reducer. As a result, the capacity of the motor can be reduced. Since the cam and the cam follower are in rolling contact with each other, there is little energy loss. Furthermore, since the motor is driven by the motor, a stable movement can be realized. That is, variations in movement due to load fluctuation and temperature fluctuation are reduced. (Problems to be Solved by the Invention) When a cam is used in a plastic working machine, the above advantages can be obtained, but the use of a cam has the following disadvantages at the same time. The amount of movement of the mold and the roll moved by the cam was constant, and it was difficult to adjust the amount of movement. The cam pattern is usually fixed, that is, the relationship between the phase and the cam lift is fixed. Therefore, when an object to be processed changes, a cam having a different cam pattern is required, and the cams need to be replaced one by one. Further, when changing the timing of the movement of the camshaft and other mechanical parts, or the timing of a plurality of cams, it is necessary to shift the mounting position of the cams. Among these drawbacks, the drawback is that it is unavoidable due to the characteristics of the cam, but what actually matters is the forward end position of the mold and roll. This is another method, for example, by changing the length of the portion connecting the cam follower and the roll manually or electrically with a screw or the like, so that the forward end position can be changed even with a cam having a fixed stroke. it can. Conventionally, this method is generally performed. However, the above drawbacks can be solved only by replacing the conventional cam, and when the processing force is large, the cam is inevitably large in size, and the replacement requires a great deal of labor and time. As for the disadvantage, since the timing adjustment shifts the mounting position of the cam, the timing of the cam cannot be realized with very high accuracy, and the final adjustment is performed by trial and error, which often takes time. Was. Therefore, an object of the present invention is to make the forward end position of a processing tool variable, and at the same time, even if an object to be processed changes, a cam having a different pattern is not required, and the cam is not replaced one by one. A plastic processing machine with a camshaft rotation control mechanism that can change the timing of the movement of the camshaft and other parts or the timing of multiple cams with high precision without shifting the mounting position of the cam To provide. (Means for Solving the Problems) In order to achieve the above object, a cam for moving a tool for processing a workpiece according to the present invention, and a cam shaft for rotatably supporting the cam are provided. A processing machine, wherein the cam processes the workpiece with the tool after the rapid advancing part and the rapid advancing part that abruptly advances the workpiece a predetermined distance when the tool is not in contact with the workpiece. A processing machine having a low-speed machining feed unit for giving a feed amount when performing the rotation, and having a rotation control mechanism for controlling rotation of the cam shaft, wherein a total low-speed machining stroke of the low-speed machining feed unit is a stroke per unit cam rotation angle. A cam formed to have the same amount and set to be equal to or larger than a desired actual low-speed feed stroke, and the rotation control mechanism includes:
The camshaft is controlled so that the angular velocity (ω) between the cam start angle and the rotation angle from the start of the low-speed feed stroke can be expressed by the following equation. Here, ω ₂ : basic constant angular velocity when feeding at a constant angle θ ₁ : end angle of basic rapid advance θ ₂ : basic low speed start angle at which actual low speed feed stroke starts. (Operation) As described above, the plastic working machine of the present invention has a single cam having a plurality of different pressure angle patterns and a rotation control mechanism for variably controlling the rotation speed of the cam shaft in one cycle. The camshaft and other parts can be moved without changing the position of the cam, eliminating the need for a cam that moves in a different pattern even if the object to be machined changes. , Or the timing of a plurality of cams can be changed with high precision.
The “pressure angle” can be defined as an angle between the (common) normal line at the contact point between the cam surface and the cam follower (follower contact) and the direction of movement of the contact, and is an element that determines the cam shape. In this specification, it may be understood as a cam shape or a cam pattern. Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same parts are indicated by the same reference numerals. FIG. 1 is a front view showing a partial structure of a plastic working machine of the present invention, that is, a rotary forming machine 1. In the drawings, only one axis driven by the cam is shown. The processing tool, that is, the roll 2 is fixed to the headstock 11 at the forward end position of the rotary molding machine 1 for processing the workpiece.
The roll 2 is disposed substantially coaxially, and its forward end position is adjusted by a roll advance end adjusting screw 3 provided on the headstock 11, and is freely adjusted to a set position. The screw 3 is moved by a gear box 5 and a pulse motor 6. The screw 3 is in contact with one end of the cam follower 9 at one end opposite to the roll 2.
And receives a predetermined pressing force. The other end of the cam follower 9 is in contact with the cam 7 and receives a predetermined pressing force from the cam 7. The cam 7 is fixed to a camshaft 8, and the camshaft 8
Is connected to a control motor, that is, a servomotor 10 via a speed reduction mechanism (not shown). Therefore, the rotation of the camshaft 8 is controlled by the servomotor 10. The headstock 11
Reciprocates on the slide 4. In this embodiment, the cam 7 has a cam pattern having a shape as shown in FIG. The cam 7 has a cam curve shown in FIG. 3 and has a shape shown in FIG. As can be seen from FIG. 2, the pressure angle pattern of the cam 7 comprises a plurality of cam patterns having different radii of curvature, the rotation of which is controlled by the servomotor 10.
For example, the cam 7 shown in FIG. 2 is a cam having a total stroke a as can be seen from the third appendix, and when viewed from the pressure angle pattern, there is a rapid advance idle feed from θ ₀ to θ ₁ first, and then theta until only a stroke (full slow working stroke) b ₁ from theta ₃ has slow processing feed, theta ₄ from subsequent theta ₃
, And rapid retreat from θ ₄ to θ ₀ continues. Rotation at a constant rotational speed by the cam 7 servomotor 10, the S-T curve was changed every other horizontal axis θ゜Wo time t _s of Figure 3. The cam curve in FIG. 4 is due to the cam having a low machining stroke represented by c. A method of producing a cam curve of low-speed machining feed having a machining stroke c shown in FIG. 4 using the cam 7 (cam shown by the cam curve in FIG. 3) shown in FIG. 2 will be described below. That is, the cam curve of the cam 7 in FIG.
First, an angular velocity suitable for processing is set using the cam 7. The basic specifications at this time are defined as follows using FIG. θ _{1 is the} basic rapid advance end angle, which is the basic rotation angle of rapid advance. θ ₂ : An (arbitrary) basic low speed start angle at which the actual low speed feed stroke starts in the cam curve for obtaining various actual low speed feed strokes c using the cam 7. θ _{3 is} a basic low speed end angle at which the entire low speed machining stroke b ends at the same time as the actual low speed feed stroke c. ω ₁ is a basic angular velocity between the start angle θ ₀ and θ ₂ of the cam 7, and is a basic rapid advance angular velocity. ω ₂ : Basic low-speed angular velocity (θ ₀ → θ ₃₆₀ ) when feeding at a constant angular velocity using the cam 7. ω ₃ : angular speed at which the actual low-speed feed stroke c is obtained when a cam curve as shown in FIG. 4 is obtained by the cam curve in FIG. 3. Note that the magnitude relationship between ω ₁ , ω ₂ and ω ₃ is a basic processing condition suitable for processing. An arbitrary relationship can be determined by (for example, test processing). Reducing the rotational speed of the part A of the cam of FIG. 2 as an example, it is possible to rotate control cam shaft to indicate angular velocity of this portion Figure 5 and Figure 6 and omega _3. At this time (as shown in FIG. 5 and FIG. 6)
The stroke b of the cam 7 is set to be larger than the stroke (actual low-speed feed stroke) c. When the rotation of the camshaft is controlled as shown in FIGS. 5 and 6, an ST curve as shown in FIG. 7 is obtained. In the above description, the machining is performed in the order of the stroke b, the stroke c, and the stroke a. However, the stroke b, the stroke c, and the stroke b can be controlled by appropriately controlling the rotation of the cam 7 (forward rotation, reverse rotation control, and the like). , Stroke a,
Processing can be performed in the order of the stroke b and the like. Figure 8 shows the S-T curve when rotated (e.g. by an angular velocity omega ₂₎ at a constant rotational speed as is done in general a cam having a cam curve of Figure 4. As can be seen by comparing FIGS. 7 and 8, FIG. 7 and FIG.
In the drawing, the low-speed machining feed has the same pattern except for the idle feed portion that is rapidly moving forward. In this idle feeding section, the processing is not affected at all because it is in a state before the workpiece hits the tool. At this time, the angular velocity ω ₁ (r.
pm) is preferably selected so as not to increase the cycle time and to minimize the maximum number of revolutions required for the motor, which is determined by the following equation. In the equation (1), t ₄ is the time (second) for the cam 7 to make one rotation, and the value in {} in the right term Means the rotation angle for advancing the machining stroke c in FIG. _3, and subtracting this value from θ ₃ is nothing less than finding the value of θ ₂ . Also, ω is rp
m. (revolutions per minute), 60 / t ₄
Is the average angular velocity of one cycle of the cam, that is, ω ₂ (fifth
FIG. 6 and FIG. 6). By transforming equation (1) using the following relationship, the following equation (2) is obtained. ω ₁ θ ₁ = ω ₂ θ ₂ − (2) ω indicates the angular velocity (rpm) of the idle feeding portion. The angular velocity of the idle feed portion corresponds to the angular velocity of θ ₀ → θ ₁ in the cam curve of FIG. 4, and uses the cam curve of FIG. 3 obtained from the cam 7 of FIG. When the actual low-speed feed stroke curve is obtained, the idle feed portion becomes θ ₀ → θ ₂ (FIG. 3), which corresponds to the angular velocity ω in this section. Accordingly, the cam 7 having a cam curve of FIG. 3 in omega ₂ theta
₀ → theta ₃₆₀ theta in same application with the conventional methods of rotating the ₀ →
between θ ₂ (jump feed) In this application, if the section of the actual low-speed feed stroke c (FIGS. 5 and 6) θ ₂ → θ ₃ is assumed to be ω ₃ smaller than ω ₂ (although the cycle is reduced), the entire cycle empty feed unit cycle increase in the in, it can compensate for that cycle decreased amount, and using the cam 7 of the cam curve showing between theta ₂ → theta ₃ in FIG. 3, real slow like Figure 4 it can be rotated at an angular velocity omega ₃ as having a cam curve having a feed stroke. In this way, one cam can be used freely as a cam having a different pattern. In this embodiment, for the sake of simplicity, in the cams shown in FIGS. 3 and 4, the feed pattern is switched, and θ is the same from θ ₁ to θ ₃ , but this θ is different. The cam of FIG. 3 can represent the cam of FIG. The cam according to the present invention is used, for example, for plastic working, and can generate a sufficient load necessary for a tool for plastic working. In this case, when a cam having a cam curve shown in FIG. 3 is selected. The speed reduction ratio changes during one cycle of the cam. When the rotation of the cam shaft is controlled as shown in FIG. 6 to move the tool as shown in FIG. 7, the torque applied to the motor shaft is as shown in FIG. Naturally, here the camshaft 8 and the servomotor
Although a speed reducer with a considerably large reduction ratio must be interposed between 10 and 10, in the case of the machining example according to the present embodiment, the motor torque required to achieve a high load during machining and a high speed during idle feed. Can be considerably smaller than when machining with a ball screw. This is because the reduction ratio is constant in the case of processing with a ball screw. Therefore, a small servomotor can be used, and the efficiency is improved. The timing between the movement of the camshaft and other mechanical parts,
In order to adjust the timing between the plurality of cams with high precision, the rotation start time of the servomotor can be controlled by arbitrarily shifting, so that the mechanical cam phase adjustment is not required. This rotation control is performed according to the flowchart shown in FIG. First, by the command program 12,
A program relating to predetermined rotation control and rotation speed of the camshaft is input, and the deviation counter 13 counts it,
The signal is input to the servomotor 10 via a digital / analog converter (D / A exchanger) 14 and an amplifier, that is, an amplifier 15. The number of rotations of the servo motor 10 is constantly monitored by the rotation detector 16 and the encoder 17, and the result is fed back to the amplifier 15 and the deviation counter 13, respectively. As described above, since the cam has the variable speed reduction mechanism, the portion where the cam pressure angle is small (high load, low speed portion)
Thus, the motor capacity can be reduced by the combination of the portions where the pressure angle of the cam is large (low load, high speed portion), and an efficient and flexible drive system can be made in combination with the above-described cam shaft rotation control. (Effect of the Invention) According to the plastic working machine of the present invention described in detail above, the following effects can be obtained. The forward end position of the processing tool can be changed, and at the same time, a small-capacity motor can be used.Even if the object to be processed changes, the cam having a different pattern is not required, and the cams are replaced one by one. The timing of the movement of the cam shaft and other parts or the timing of the plurality of cams can be changed with high accuracy without shifting the mounting position of the cam.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial sectional view of a plastic working machine showing an embodiment of the present invention, and FIG. 2 is a diagram showing an example of a cam pattern of a cam for explaining the present invention. FIG. 3 is a graph showing a cam curve corresponding to FIG. 2, and FIG. 4 is a desired curve desired to be obtained from the present invention in which a low-speed machining stroke is represented as c from the cam curve of FIG. 5 and 6 are graphs showing cam curves of different cams, and FIGS. 5 and 6 are graphs showing cam cam shaft rotation control for explaining the present invention having the cam curves of FIG. 3 using the cams of FIG. FIG. 7 is a graph showing the S-axis obtained by the rotation control of the present invention obtained by using the cam of FIG. 2 and improving the cam curve shown in FIGS. 4 and 8 during the rapid advance. is a graph showing the T curve, FIG. 8, when the rotational speed is constant (omega _2), second It is a curve which shows an example of a desirable ST curve of this invention obtained using the cam of the figure, FIG. 9 is a figure which shows the flowchart for controlling the rotation angle and rotation speed of the cam of this invention. FIG. 10 is a graph showing the torque applied to the motor when the rotation of the camshaft of the present invention is controlled. [Description of Signs of Main Parts] 1 ... Plastic processing machine 2 ... Roll 7 ... Cam 8 ... Cam shaft 10 ... Servo motor

Claims (1)

(57) [Claims] A processing machine with a rotation control mechanism, comprising: a cam for moving a tool for processing a workpiece; a cam shaft rotatably supporting the cam; and a rotation control mechanism for controlling the number of rotations of the cam shaft. The cam includes at least a rapid advancing portion that abruptly advances the workpiece by a predetermined distance when the tool does not contact the workpiece, and a feed when the workpiece is machined by the tool subsequent to the rapid advancing portion. A rotation control mechanism for variably controlling a rotation speed of the camshaft in one cycle, wherein the rotation control mechanism variably controls a rotation speed of the camshaft in one cycle. 2. A cam in which the total low-speed machining stroke of the low-speed machining feed section is set to be equal to or larger than a desired actual low-speed feed stroke, and the rotation control mechanism performs rotation from a cam start angle to the start of the desired low-speed feed stroke 2. The processing machine with a rotation control mechanism according to claim 1, wherein the camshaft is controlled so that an angular velocity ([omega] ₁ ) between the angles can be expressed by the following equation. Here, omega _2: constant angular basic constant angular velocity when sending in theta _1: different desired end angle rapidly advanced from the start of rotation when rotating the cam pattern ω ₂ θ _2: desired real slow feed stroke 2. Basic low speed start angle to start The processing machine with a rotation control mechanism according to claim 1, wherein the rotation control mechanism includes a control motor. 4. The processing machine with a rotation control mechanism according to claim 3, wherein the cam is a single cam composed of cam patterns having different radii of curvature.