JP2000043058A - Resin molding method and machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for certainly suppressing rotary vibration generated in the rotary power transmission mechanism in a molding machine for a resin or the like by a relatively simple means sufficient in a small sum of investment even if an existing molding machine is remodeled to be attached and the molding machine provided with this suppressing means. SOLUTION: Molding is performed while the inherent rotary vibration generated in a transmission mechanism transmitting rotary power to a load 4 such as a roll or the like, for example, a speed reducer is absorbed. A buffer device 3 is used in the absorption of this inherent rotary vibration. As the buffer device 3, it is pref. to employ a device having such a structure that the end parts of two rotary shafts to which the rotary power to the load 4 is transmitted are mutually connected by a deformable elastomer within the plane crossing the axial line of the rotary shafts at a right angle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission mechanism for transmitting rotational power generated by a motor or the like, which suppresses the rotational vibration when a rotational vibration is generated due to the meshing period of gears of a speed reducer or the like. The present invention relates to a molding method and a molding machine.

[0002]

2. Description of the Related Art In general, in a molding machine made of resin or the like, molding is performed by transmitting rotational power generated by a motor or the like to a load via an appropriate power transmission mechanism. Here, the load is a mechanical element that performs some molding or processing operation on a resin or the like by a given rotational power, for example, a roll of a roll forming machine such as a calender roll, a heating / cooling roll, and a pressurization. There are rolls, mixing rolls, rolling rolls, squeezing rolls, screws for extruders or injection molding machines, and the like.

Incidentally, the power transmission mechanism includes various transmission means such as a ball screw, a nut, and a speed reducer. In general, when power is transmitted by these power transmission mechanisms, rotational vibration is generated. Poor molding may occur. Here, as shown in FIG. 4, the rotational vibration refers to a state in which a vibration component (b) is applied to a steady rotational speed component (a) in the power transmission mechanism.

For example, when a speed reducer is used as a power transmission mechanism, rotational vibration having a specific period and amplitude is generated in accordance with the meshing period of the gears in the speed reducer, and this rotational vibration is transmitted to a load. It is known to cause various problems. The surface unevenness of the resin in extrusion roll molding is a typical example. In this example, the rotational vibration given from the reduction gear to the rotating roll contacting the molten resin surface extruded from the extruder is a resin molded product. This may cause minute undulation on the surface. In addition, a driving device that rotates a load such as a bearing, a pulley, or a chain is included as an element that causes the rotation vibration.

In order to reduce this problem, a signal from a position detector connected to the rotating shaft of the motor is received, and a correction signal having the same cycle as the rotational vibration is input to a servo control system of the motor, so that the motor is controlled. Japanese Patent Application Laid-Open No. 62-242151 discloses an apparatus that controls the rotation to suppress vibration generated in an output system such as a speed reducer by a motor serving as a driving source. An apparatus for feeding back a correction function signal for canceling the vibration to the input of the automatic control device when a resonance state is caused by the method disclosed in
No. 9141. Further, a method of transmitting power using a speed reducer that does not easily generate rotational vibration, such as a planetary roller type speed reducer, has also been proposed.

[0006]

However, as described in each of the above publications, a rotational vibration appearing on an output shaft or the like of a rotational power transmission mechanism is measured by a sensor, and a signal from the sensor is converted into a rotational vibration suppression signal. In a control device that converts and further suppresses the rotational vibration of the load by feeding back the signal to the input of the drive motor, a motor in which the drive motor itself has an excellent output response characteristic to the input of the rotational vibration control signal, For example, it must be a servomotor. Therefore, when the above-mentioned control device is attached to a molding machine of an existing resin or the like, if the existing driving motor of the molding machine is not of such a type, the driving motor itself must be replaced. In such a case, a new driver and other input devices need to be provided, and a large investment is required.

[0007] In addition, the speed reducer such as the above-mentioned planetary roller type speed reducer, which hardly generates rotational vibration, is expensive in itself and tends to be large in size. Therefore, when mounting to an existing molding machine made of resin or the like, mounting is often difficult, and even if mounting is possible, a large amount of equipment remodeling cost is required in many cases. In addition, for a power transmission mechanism other than the speed reducer, such as a rotational vibration generated from a bearing or a joint, which causes an error in processing accuracy or mounting accuracy, another solution is required. was there.

An object of the present invention is to solve the above problems. That is, the present invention
A method that reliably suppresses rotational vibration generated in the transmission mechanism of rotational power in a molding machine such as a resin by using a relatively simple means that requires a small investment even if the existing molding machine is modified and installed. It is another object of the present invention to provide a molding machine provided with such a suppressing means.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention does not prevent the generation of the inherent rotational vibration in the transmission mechanism of the rotational power, but rather the generation of the inherent rotational vibration itself. Is characterized in that transmission of rotational vibration to a load is suppressed by absorbing the absorption after permitting.

[0010] A shock absorber is used to absorb the inherent rotational vibration. As the shock absorber, one having a structure in which ends of two rotation shafts to which rotation power to the load is transmitted are connected by an elastic body that can be deformed in a plane perpendicular to the axis of the rotation shaft. It is preferable to employ it.

The moment of inertia of the load is 10
0 kg · m ² or less, and the torsional torque of the rotating power is 500
In the case of kgf · m or less, it is desirable that the torsion spring constant of the shock absorber be 5000 kgf · m / rad or less.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a basic configuration of a rotational vibration suppressing mechanism in a molding machine for resin or the like according to the present invention. In the present embodiment, a motor 1 that generates rotational power
A speed reducer 2 as a power transmission mechanism for efficiently transmitting a driving force by reducing the rotational speed of the high-speed rotational power generated by the motor 1; and a load 4 driven by the rotational power reduced by the speed reducer 2. By installing a shock absorber 3 subsequent to the speed reducer 2 in the molding machine consisting of the following, the rotational vibration generated in the speed reducer 2 is absorbed by the shock absorber 3, and the rotational vibration is transmitted to the load 4. Restrained. The specific location of the shock absorber 3 may be either inside or outside the casing of the speed reducer 2.

For example, in the case of an extruder, a multi-stage helical wheel subjected to surface hardening and tooth grinding is usually used as the speed reducer 2, and a one-stage gear, a spur gear, or the like is used depending on the application. Sometimes. The rotational vibration generated in such a speed reducer 2 has a property that the rotational speed periodically changes according to the number of gear teeth in the speed reducer 2.
10Hz if a gear with zero teeth rotates once per second
Rotational vibration is generated based on the frequency. This frequency is uniquely determined by the number of teeth and the number of revolutions of the gear of the reduction gear 2, and a vibration component unique to the gear is generated literally.

As described above, since the reduction gear is generally configured by combining a number of gears, the vibration components of each gear are superimposed on the entire reduction gear, and the rotational vibration inherent to the reduction gear is generated. appear. Therefore, as shown in FIG. 5, the inherent rotational vibration of the speed reducer has a complex vibration waveform in which a plurality of frequencies including a low-frequency component and a high-frequency component are combined with a steady rotational speed component. It is known that the frequency of the rotational vibration increases as the rotational speed of the motor 1 increases.

In the embodiment shown in FIG. 1, since the rotational vibration generated in the speed reducer 2 is absorbed by the shock absorber 3, a complicated control for suppressing the generation of the rotational vibration in the speed reducer 2 is required. In addition, it is not necessary to use an expensive servomotor or planetary roll type reduction gear as the motor 1 or the reduction gear 2, respectively. Therefore, as compared with the case where the drive motor or the power transmission mechanism is modified, it can be easily attached to an existing molding machine, and the modification cost can be reduced.

The structure of the shock absorber 3 used in the present invention is not particularly limited as long as it has a function of attenuating the transmission of rotational vibration applied to the rotational power input to the shock absorber 3. Is an elastic body having an appropriate spring constant that can be deformed in a plane orthogonal to the axis of the rotating shaft without tightening the ends of the two rotating shafts to which the rotating power to the load is transmitted. It is preferable to have a flexible connection structure.

FIG. 2 is a sectional view showing an example of a preferred structure of the shock absorber 3 used in the present embodiment, and FIG. 3 is a sectional view taken along line AA of FIG. As is clear from the drawings, the shock absorber 3 shown in FIGS. 2 and 3 includes a first flange joint 5 and a first flange joint 5 attached to first and second rotating shafts (not shown) that mutually transmit rotational power. It has a coupling structure in which the ends of the second flange joint 6 are connected to each other. The second flange joint 6 is held by a holder 7, and the holder 7 is connected to the first flange joint 5 by bolts and the like. Are joined. Therefore, the first flange joint 5 and the holder 7 are integrated into a second flange joint 6
Can rotate relative to.

As shown, the second flange joint 6
In the vicinity of the outer periphery of the flange portion, a through-hole 6a having an elliptical cross section penetrating the flange portion is formed. In the present embodiment, four through-holes are provided at positions separated from each other by 90 degrees, but the number of the through-holes 6a and the locations of the perforations can be adjusted as needed.

On the other hand, on the surface of the first flange joint 5 and the holder 7 facing the second flange joint 6, a groove having the same oblong cross section as the through hole 6a is provided at a position corresponding to the through hole 6a. 5a and 7a are engraved, respectively, and a spring element 10 composed of a spring 8 as an elastic body and a spring holding member 9 is disposed in a closed space defined by the through hole 6a and the grooves 5a and 7a.

As shown in detail in FIG. 3, the spring element 10 has a spring 8 having an appropriate spring constant at both ends by a spring holding member 9 having an outer shape adapted to the inner surfaces of the through holes 6a and the grooves 5a and 7a. The structure is held.
In the present embodiment, two springs 8 are connected to two spring holding members 9.
To form one spring element 10, but the number of springs 8 can be adjusted as appropriate according to the required degree of cushioning function. In addition, as the material of the spring 8, a resin, a fiber-reinforced composite material, or the like can be used in addition to a metal such as a normal spring steel. In the shock absorber 3 of the present invention, an elastic material such as rubber may be used as an elastic body other than the spring.

In the present embodiment, as shown in FIG. 2, the length of the spring holding member 9 is
Is set to be larger than the thickness of the flange portion. Therefore, a part of the spring element 10 protrudes from the through hole 6a of the second flange joint 6, and the protruding part is formed by the groove 5a formed on the surface of each of the first flange joint 5 and the holder 7 described above. , 7a. Thus, the first flange joint 5 and the second flange joint 5
Are connected to each other via a spring element 10.

As is apparent from the drawings, the spring 8 in the present embodiment is connected to the axes of the first and second rotating shafts (not shown) connected to the first and second flange joints 5 and 6, respectively. It is possible to expand and contract in an orthogonal plane. Therefore, when rotational power is applied to the first flange joint 5 from the rotary shaft (not shown), the grooves 5a, 7
One spring holding member 9 of the spring element 10 is pressed through the inner wall of the groove a. The spring 8 is compressed, and as a reaction, the other spring holding member 10 of the spring element 10 presses the inner wall surface of the through-hole 6a to generate rotational power.
To the flange joint. As described above, since the rotational power is transmitted from the first flange joint to the second flange joint 6 via the spring 8, the rotational vibration applied to the rotational power is effectively absorbed.

Incidentally, the above-described shock absorber 3 absorbs rotational vibrations of various frequencies, but depending on the specific structure inside the shock absorber 3, there are frequencies having particularly high absorption efficiency. In the shock absorber 3 according to the present embodiment, the frequency of the rotational vibration that can be effectively absorbed can be appropriately adjusted by the inertia moment of the load, the torsion spring constant of the shock absorber 3, and the torsional torque applied to the rotating shaft. Here, the torsion spring constant refers to a force required when rotating by a unit angle, and in the present embodiment, the torsion spring constant is a compression spring constant of the spring 8 and a radial mounting of the spring element 10 from the rotation axis. It is adjusted by arbitrarily selecting the position, the number of the spring elements 10 attached, or the number of the springs 8 in the spring element 10.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In a molding machine having a rotation suppressing mechanism shown in FIG. 1, a shock absorber 3 having a coupling structure shown in FIGS. It was measured. In the present embodiment, the shock absorber 3 having a torsional spring constant of 256 kgf · m / rad is used under the condition that the moment of inertia of the load 4 is 1.6 kg · m ² and the torsion torque applied to the rotating shaft is 0.45 kgf · m. As a result, a result was obtained in which the rotational vibration generated by the reduction gear 2 was reduced by 50% or more in the frequency region of 5 Hz or more.

[0025]

According to the present invention, it is possible to prevent the transmission to a load by absorbing the inherent rotational vibration generated in the transmission mechanism of the rotational power. It is possible to perform good molding without causing the molding.

Moreover, since the absorption of the rotational vibration can be achieved only by installing the shock absorber in the transmission mechanism, the mounting to the existing molding machine is easy. Also, since there is no need to use an expensive servo motor as the drive source, and because it is not necessary to employ an expensive planetary roller type reducer, the remodeling cost for suppressing rotational vibration in existing molding machines is greatly reduced. Can be reduced.

Further, the present invention can cope with not only the rotational vibration at the speed reducer but also the rotational vibration generated in other power transmission mechanisms.

The shock absorber has a structure in which ends of two rotating shafts to which rotational power to a load is transmitted are connected by an elastic body that can be deformed in a plane orthogonal to the axis of the rotating shaft. When a shock absorber is used, the shock absorber can be made simple and have a high absorption effect.

[Brief description of the drawings]

FIG. 1 is a block diagram of a method for suppressing and controlling rotational vibration of a power transmission mechanism according to an embodiment of the present invention.

FIG. 2 is a sectional view showing an example of an embodiment of a shock absorber according to the present invention.

FIG. 3 is a view taken along line AA of FIG. 2;

FIG. 4 is a conceptual diagram showing a combined state of inherent rotational vibration generated in the rotational power transmission mechanism.

FIG. 5 is a conceptual diagram showing details of inherent rotational vibration generated in a speed reducer as an example of a rotational power transmission mechanism.

[Explanation of symbols]

 Reference Signs List 1 motor 2 reduction gear 3 shock absorber 4 load 5 first flange joint 6 second flange joint 7 holder 8 spring 9 spring holding member 10 spring element

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Tadanobu Ikeda 20-1 Miyukicho, Otake City, Hiroshima Prefecture Mitsubishi Rayon Co., Ltd. Central Research Laboratory (72) Inventor Takeaki Amakawa 201-1 Miyukicho, Otake City, Hiroshima Prefecture No. Mitsubishi Rayon Co., Ltd. Otake Works F-term (reference) 4F201 AM00 AM32 BA08 BC01 BC02 BD02 BD04 BD05 BS10 4F204 AM00 AM32 FA06 FQ40 4F206 AM00 AM32 JT37 JT40 4F207 AM00 AM32 KM30

Claims (4)

[Claims] 1. A method of molding a resin, wherein molding is performed while absorbing inherent rotational vibration generated in a mechanism for transmitting rotational power to a load. 2. A resin molding machine characterized in that a transmission mechanism for transmitting rotational power to a load including an element generating a specific rotational vibration is provided with a shock absorber for absorbing the specific rotational vibration. 3. A structure in which the shock absorber is configured such that ends of two rotation shafts to which rotation power to the load is transmitted are connected by an elastic body that can be deformed in a plane perpendicular to the axis of the rotation shaft. The resin molding machine according to claim 2, comprising: 4. The load has a moment of inertia of 100 kg.
· M ² or less, the torsional torque of the rotational power 500kgf
The resin molding machine according to claim 2, wherein the torsional spring constant of the shock absorber is 5000 kgf · m / rad or less when the pressure is equal to or less than m.