JP2003311553A - Press-fitting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of generation of permanent distortion in each workpiece and formation of cracking and breakage in the same at the time of application of an excessive press-fitting force in an attempt of carrying out positive press-fitting work, and a problem of increase in equipment manufacturing cost. <P>SOLUTION: The press-fitting apparatus comprises a moving means 1, a load sensor 9, a location detecting means 10, an inertial weight 3, a piezoelectric actuator 4, and a control means 11. The moving means 1 is formed of a press-fitting cylinder or the like, for moving the workpiece in a press-fitting direction and a backward direction, based on electric power or hydraulic or pneumatic pressure as a driving force. The load sensor 9 detects a press-fitting force to the workpiece. The location detecting means 10 is formed of a linear sensor or the like, for detecting a moved location of the moving means. The inertia weight 3 is attached to a lower edge of the moving means. The piezoelectric actuator 4 is attached to a lower edge of the inertia weight. The control means 11 stores therein a press-fitting force set value and a press-fitting location set value which are set according to the shape of the workpiece, compares the press-fitting force set value with a press-fitting force signal detected by the load sensor, and calculates a press-fitting force deviation. Further, the control means compares the press-fitting location set value with a moved location signal detected by the location detecting means, and calculates a press-fitting locational deviation, to thereby drive the moving means according to the press-fitting force deviation and the press-fitting locational deviation. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a press-fitting device which enables accurate and reliable press-fitting of parts and incorporation of press-fitting.

[0002]

2. Description of the Related Art Conventionally, as a means for press-fitting another member into a member, a hydraulic or pneumatic cylinder is used to press-fit the members together, but at the time of press-fitting, one member or both members are warmed. By chilling or chilling, the mutual dimensions were loosely fitted and relaxed to the extent of intersection.

However, in this press-fitting method, since it is necessary to heat or cool the parts, it has become an unsuitable method due to the recent reduction in equipment manufacturing cost and efficiency improvement of kinetic energy. Therefore, in recent years, it is being switched to press-fitting at room temperature, but in that case, it becomes press-fitting with strict tolerances of parts, things that can not be press-fitted to a predetermined position or the bottom of the hole, scrapes on the wall surface of the press-fitted object, its metal And the like are narrowed between the workpieces on the bottom surface, resulting in a floating state.

[0004]

Therefore, it is conceivable to increase the press-fitting force in order to secure a reliable press-fitting work. However, if the press-fitting force is too high, permanent distortion occurs between the works, causing cracks or damage. It also causes an increase in equipment manufacturing costs, and in the case of parts with bottoms, there is a possibility that they may be shipped in a half-pressed state without a confirmation means, and it is impossible to generate the prescribed function during operation in the market. There was a problem that market complaints occurred.

The present invention is intended to solve the above-mentioned problems, and an object of the present invention is, in a press-fitting device for inserting a work into a predetermined position, the insertion force and position of the tip jig to the shape of the work. In order to provide a press-fitting device that can optimally set and improve the assembly accuracy of the work by low pressure rolling press-fitting with no work distortion, and that can detect and warn for abnormalities such as foreign matter mixing. is there.

[0006]

The press-fitting device of the present invention achieves the above-mentioned object, and the means of claim 1 is to move or return in the work-press-fitting direction by using electric or hydraulic / pneumatic pressure as a drive source. Moving means such as a press-fitting cylinder to be operated, a load sensor for detecting a pressure input to the work,
Position detecting means such as a linear sensor for detecting a moving position of the moving means, an inertia weight attached to a lower end of the moving means, a piezoelectric actuator attached to a lower end of the inertia weight, and a work shape according to the shape of the workpiece. The set pressure input setting value and the press-fitting position setting value are stored, the pressure input setting value and the pressure input signal detected by the load sensor are compared, and the pressure input deviation which is the deviation thereof is calculated to obtain the press-fitting position. A control means for comparing the set value and the moving position signal detected by the position detecting means to obtain a press-fitting position deviation which is the deviation, and driving the moving device according to the press-fitting deviation and the press-fitting position deviation. It is equipped with.

According to a second aspect of the present invention, in the press-fitting device of the first aspect, a tip jig for holding a work at the tip of the press-fitting rod and guiding it to a head hole, a holder for holding the tip jig, and a holder for holding the tip jig and the holder. It is equipped with a piezoelectric actuator that vibrates, and an inertia weight that holds the tip jig and the holder and the piezoelectric actuator and has a mass larger than those masses, and the tip jig and the holder are capable of stretching vibration of any amplitude and any frequency. It is characterized by

According to a third aspect of the present invention, in the piezoelectric device according to the first aspect, when the bottom of the hole in the head of the work can be confirmed, the piezoelectric actuator is temporarily returned to the contracted end,
In addition, the inertia weight is moved in the press-fitting direction and held when it reaches a preset press-in force, then the piezoelectric actuator is extended in DC mode, the load change during that time is measured by the load sensor, and the voltage applied to the piezoelectric actuator is measured. The load deviation / position deviation is calculated from the extension distance converted from and the load change accompanying it, and the presence / absence of foreign matter between the workpiece and the bottom surface is determined by the deviation between the calculation result and a preset normal value. It is characterized by having done.

According to a fourth aspect of the present invention, the weight of the tip jig, the holder and the piezoelectric actuator attached to the press-fitting rod according to the second aspect is lightened to increase the resonance frequency.

According to a fifth aspect of the present invention, the mass of the inertia weight is set to be sufficiently larger than the total mass of the tip jig attached to the press-fitting lot, the holder and the piezoelectric actuator. The reaction force is absorbed by the inertia energy of the inertia weight.

According to a sixth aspect of the present invention, the vibration frequency of the piezoelectric actuator according to the second aspect is automatically changed from a low range to a high range, and a resonance frequency between them is detected from the input power,
The resonance frequency is maintained, and the means of claim 7 detects that the resonance frequency of the piezoelectric actuator in claim 2 changes with a press-fitting load change, and automatically corrects and maintains the optimum frequency. It is characterized by doing so.

According to an eighth aspect of the present invention, by constantly driving the piezoelectric actuator according to the second aspect at a resonance frequency, static friction associated with press-fitting is reduced with a minimum energy, and the work is press-fitted with a small pressure that does not cause distortion. The means of claim 9 is characterized in that
When the press-fitted work bottoms out, the fact that the bottoming work is completed can be determined by utilizing the fact that the resonance frequency of the piezoelectric actuator changes greatly.

According to a tenth aspect of the present invention, the tip jig according to the second aspect is provided with a pressing rod that moves back and forth in the center, and a hooking body that spreads outward as the pressing rod advances is provided at least twice on the outer periphery of the pressing rod. The present invention is characterized in that it is movably provided and that the claws formed on the hook body are hooked on the ring-shaped work by expanding the hook body outward.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION A portable device for carrying out a press-fitting device according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the entire press-fitting device of the present invention. 1 is a cylinder whose piston is expanded and contracted by electric, hydraulic or pneumatic pressure, 2 is a press-fitting rod which is vertically moved by expansion and contraction of the piston of the cylinder 1, and 3 is a cylinder. An inertia weight 4 having a large mass attached to the lower end of the press-fitting rod 2 is attached to the lower end of the inertia weight 3, and a piezoelectric actuator 5 vibrated by an output from a control means 11 described later is attached to the lower end of the piezoelectric actuator 4. A hole 8 in a workpiece 8 to be attached and described later
A holder for avoiding interference with the periphery of a, 6 is attached to the lower end of the holder 5 and has a tip jig for press-fitting a work 7 described later into a hole 8a of the head 8, and 7 is a ring shape or a ring shape with a bottom. Work, 8 is the work 7 has a hole 8
The head is integrated by being pressed into a.

9 is attached to the upper end of the cylinder 1,
A load sensor for measuring the load of the cylinder 1, 10 is a linear sensor for measuring the moving distance of the press-fitting rod 2, and 11
Is a load comparison means for comparing the output from the load sensor 9 with a preset load to obtain a load deviation, and the output from the linear sensor 10 with a preset press-fitting position for obtaining a position deviation. Control means having a comparison means for controlling the movement of the cylinder 1 and the piezoelectric actuator 4 from these deviations, and 12 amplifies the output from the control means 11 and outputs an output for controlling the piezoelectric actuator 4. A power amplifier 13 for sending out is a display for displaying an abnormality judgment and an operation status by the control means 11.

The load sensor 9 may be provided inside the press-fitting rod 2 or inside the cylinder 1,
It suffices if the load received by the press-fitting rod 2 can be detected. Also,
The linear sensor 10 may be an outrigger shape having one end fixed to the working rod tip of the cylinder 1, or may be a rotary encoder that detects the rotation of the electric motor if the cylinder 1 is of the electric screw type.

The control means 11 also includes a solenoid valve for controlling the oil / pneumatic cylinder, a servo valve, a motor servo amplifier, and the like. Further, the power amplifier 12 is composed of a drive amplifier circuit and a control circuit, and the power amplifier 12 has a function of arbitrarily generating and outputting a waveform by using each setting value of the waveform, cycle, and peak shown in FIG. With this, the optimum vibration can be set according to various work shapes and press-fitting conditions.

For example, the waveform at the left end of FIG. 3 shows a steep forward stroke and a gradual contraction, but when the contact surface between members is high in viscosity, this waveform quickly presses forward to cut off the viscosity, and the mass is large. By slowly shrinking the press-fitting rod 2 and the inertia weight 3 in accordance with the advancing speed, it becomes possible to operate without forming a gap between the tip jig 6 and the work 7.

Next, the operation based on the above configuration will be described with reference to FIG.
In the state where the work 7 is mounted on the tip jig 6, the press-fitting set value and the press-fitting position set according to the type and shape of the work 7 stored in the control means 11 will be described. Based on this, a drive signal is input to the cylinder 1 via the power amplifier 12, the press-fitting rod 2 is extended, the tip jig 6 is lowered via the inertia weight 3, the piezoelectric actuator 4, and the holder 5, and the work 7 is moved to the head 8. The hole 8a is approached.

At this time, the control means 11 obtains the load deviation and the position deviation by the output from the load sensor 9 and the load comparison means of the control means 11, and the output from the linear sensor 10 and the press fit position comparison means of the control means 11. Based on the result, when the work 7 comes into contact with the hole 8a of the head 8 and the load is output from the load comparing means whose load has risen to a preset threshold value, the piezoelectric actuator 4 has a preset designated frequency, Alternatively, while changing the frequency from the low range to the high range, the resonance point shown in FIG. 3 is obtained to start the vibration and shift to the vibration press-fitting.

The power amplifier 12 for driving the piezoelectric actuator 4 has a resonance detecting function in addition to the frequency setting function, and is used in a test run or the like when the resonance frequency at the time of press fitting is unknown in advance. That is, although the operation starts at the same time as the start of press-fitting, the load sensor 9 also starts operating at the same timing, and when the press-fitting load rises to the load preset in the control means 11, the power amplifier 12 keeps the load and the piezoelectric element of the power amplifier 12 is maintained. The actuator 4 is swept from a low frequency to a high frequency.

Naturally, the press-fitting progresses and the work 7 moves and advances,
Although the load changes with the forward movement, the control means 11 advances the press-fitting cylinder 1 so as to maintain the load at a constant value, and holds the press-fitting load at a constant value. Then, the power amplifier 12 monitors the input power at the time of sweep driving, regards the frequency of the power bottom peak as the resonance frequency under constant load, and controls the oscillation so as to maintain the frequency.

Then, the press-fitting due to the vibration is continuously performed and the power amplifier 12 for driving the piezoelectric actuator 4 continues to vibrate at the optimum efficiency while maintaining the resonance frequency and advancing so as to maintain the press-fitting load. Further, although a reaction force vibration due to the vibration press-fitting by the piezoelectric actuator 4 is generated in the driving device side direction, this reaction force has a high vibration frequency and an extremely small amplitude.

On the other hand, the receiving side has a large mass including the inertia weight and the press-fitting rod, and the inertia of this portion absorbs most of the vibration reaction force, and as a result, the averaged continuous reaction of a very low frequency continues. Become power. This reaction force is made to oppose by the cylinder hydraulic force of the moving device, and is continuously pressed. As a result, the vibration is maintained only from the inertial weight to the tip portion, and apparently, the midpoint of the expansion / contraction stroke of the press-fitting actuator 4 accompanying the minute press-fitting advance of the tip portion is continuously moved forward and press-fitted.

When the work 7 contacts the bottom of the hole 8a in the head 8 at the final stage of press-fitting, the vibration frequency changes abruptly, so that it can be determined that press-fitting has ended.
Further, by monitoring the amount of movement from the start of work to this abrupt change, it is possible to accurately and quantitatively determine the normal end of the press-fitting work.

Further, when the bottoming is confirmed, the piezoelectric actuator 4 is shortened to the shortest point, the press-fitting rod 2 of the moving device is moved forward at a slight speed, and the position is maintained when the pressure is increased to the threshold load. After that, the piezoelectric actuator 4 is continuously extended at a low speed, and the work 7 is pressurized to the bottom surface of the hole 8a up to a specified pressure. At this time, the load / position deviation is calculated from the load corresponding to the position converted from the applied voltage, and the graph pattern of the designated section is generated. By comparing this with the normal setting pattern area shown in FIGS. 4 and 5,
It is possible to determine whether the foreign matter is mixed between the work 7 and the bottom surface of the hole 8a as shown in FIG.

That is, since the linear sensor 10 for detecting the stroke of the cylinder 1 measures the upper portion of the press-fitting position, the tip jig 6 vibrates at a frequency higher than the moving speed of the work 7, and therefore the average position thereof. Is assumed to be measured, and the characteristic curve of FIG. 5 is assumed from this information and the information from the load sensor 9. This curve is a curve that is calculated by calculating backward from the bottomed position, and the instantaneous value at that time is plotted. By enlarging the situation when the work 7 and the bottom surface of the hole 8a of the head 8 are in contact, an abnormality judgment is made. Can be performed more accurately.

When the foreign matter is caught, most of the foreign matter is scrap metal scraped off the bottom wall surface of the hole 8a of the head 8 by the work 7, and when the foreign matter is caught, the load rises faster than usual when viewed from the load. After the start, the metal scraps are crushed, so that the load increase rate rises in a smooth state, and the frequency rises in a smooth state in the power vs. frequency comparison of FIG. When this part is compared with the normal state, as shown in FIG. 4, in the normal state, the load repulsion occurs immediately after the surfaces come into contact with each other, so that the load that has changed due to the wall friction rises substantially vertically, and The frequency also changes significantly as shown in FIG.

Then, as means for determining this abnormality,
In the case of the load vs. position shown in FIG. 4, a judgment virtual line passing through the position where the bottomed confirmation load is reached is assumed, and the judgment evaluation value of the point where this straight line intersects each regulation curve = load × bottomed position It is possible to determine the presence / absence of a foreign substance based on the size of the specified value, and determine the abnormality. Also, in the case of the power vs. frequency shown in FIG. 5, since the frequency changes gently as described above, it is possible to judge from the relative difference.

Although it is possible to determine a foreign substance such as a metal scrap in the above-described operation, in order to perform the determination more reliably, the piezoelectric actuator 4 is checked in the bottomed confirmation step after the determination of the foreign substance is performed. The cylinder 1 to the contracted end, drive the cylinder 1 forward and press it until the load rises to a preset value, and press-fit rod 2 to maintain that position.
The piezoelectric actuator 4 is slowly extended while the position is controlled to press the work 7 against the bottom surface.

At this time, the load-position characteristic curve is drawn again from the load increase and the extension distance in terms of piezoelectric actuator voltage, and the foreign matter is judged again by the method described above. This allows
A normal value means that foreign matter such as metal scrap is sufficiently crushed by double press fitting, and there is no risk of the work 7 sinking further, and if it is still an abnormal determination, it is determined to be defective and disposed of. It becomes possible.

When the work 7 is ring-shaped, the tip jig 6 is provided with a pressing rod 6a for moving back and forth inside the center as shown in FIG. 7, and the pressing rod 6a is extended outward by expanding the pressing rod 6a. At least two hooks 6b are rotatably provided on the outer circumference of the pressing rod 6a, and the claws 6b ₁ formed on the hooks 6b are hooked on the ring-shaped work 7 by expanding the hooks 6b to the outside. .

As a result, it is possible to prevent the work 7 from falling off or being obliquely inserted when the work 7 is inserted into the hole 8a of the work 7 at the initial stage of the work, and to perform the press-fitting work at the stage when an abnormal load or the like due to a dimension defect is detected. The work can be interrupted before the work 7 is pulled out or repaired by the hook body 6b during the press-fitting, or the work can be interrupted before a non-reproducible defect occurs.

[0034]

As described above, according to the present invention, the piezoelectric actuator and the weight for converting the vibration reaction energy of the piezoelectric actuator into the inertia energy are provided at the tip of the moving means such as the press-fitting cylinder, and only the tip vibrates to reduce static friction. However, since it can be press-fitted with a light force, it is possible to check whether the work has bottomed in the hole in the head from the load near the bottom and position change information, and it is also possible to detect abnormalities such as foreign matter biting in and diagonal insertion. is there.

Further, with respect to the work judged to be abnormal, the pass / fail difference confirmation can be performed during a series of operations again by a slow motion close to static pressurization, and when the work is inserted into the hole of the head. Can be prevented from falling off and diagonally inserted.In addition, the press-fitting work is interrupted at the stage when an abnormal load is detected due to a dimensional defect, and the work is pulled out during the press-fitting, repaired or repaired or the work cannot be performed before it becomes defective. It has the effect of being able to interrupt the.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of a press-fitting device according to the present invention.

FIG. 2 is a diagram showing a load versus distance curve.

FIG. 3 is a diagram showing an output curve of a power amplifier.

FIG. 4 is a diagram showing a load versus position curve.

FIG. 5 is a cross-sectional view showing a power vs. frequency curve.

FIG. 6 is a diagram showing a state in which foreign matter is present between a work and a hole in a head.

FIG. 7 is a cross-sectional view showing details of a tip jig.

[Explanation of symbols]

1 Cylinder 2 Press-fit Rod 3 Inertial Weight 4 Piezoelectric Actuator 5 Holder 6 Tip Jig 6a Push Rod 6b Hook 6b ₁ Claw 7 Workpiece 8 Head 8a Hole 9 Load Sensor 10 Linear Sensor 11 Control Means 12 Power Amplifier 13 Indicator

Claims (10)

[Claims] 1. A moving means such as a press-fitting cylinder that moves or returns in the work press-fitting direction using an electric or hydraulic / pneumatic pressure as a drive source, a load sensor that detects a pressure input to the work, and a moving position of the moving means. Position detecting means such as a linear sensor for detecting the inertial weight, an inertia weight attached to the lower end of the moving means, a piezoelectric actuator attached to the lower end of the inertia weight, and a pressure input setting set according to the work shape. The value and the press-fitting position set value are stored, the press-fitting set value is compared with the press-in setting value detected by the load sensor, and the press-fitting deviation which is the deviation thereof is obtained. The moving position signal detected by the means is compared, the press-fitting position deviation which is the deviation is calculated, and the moving device is driven according to the press-fitting deviation and the press-fitting position deviation. A press-fitting device comprising: a moving control means. 2. The press-fitting device according to claim 1, wherein a tip jig that holds the work at the tip of the press-fit rod and guides it to the head hole, a holder that holds the tip jig, and a piezoelectric actuator that holds and vibrates the tip jig and the holder. And an inertia weight holding the tip jig and the holder and the piezoelectric actuator and having a mass larger than those masses,
A press-fitting device characterized in that the tip jig and the holder are capable of stretching vibration of arbitrary amplitude and frequency. 3. The piezoelectric device according to claim 1, wherein when the work is confirmed to have a bottom in the hole in the head, the piezoelectric actuator is temporarily returned to the contracted end, and the inertia weight is moved in the press-fitting direction to be preset. Hold at the time of reaching the pressure input, then extend the piezoelectric actuator in DC mode, measure the load change during that time with the load sensor,
A load deviation / position deviation is calculated from the extension distance converted from the voltage applied to the piezoelectric actuator and the accompanying load change, and the deviation between the calculation result and a preset normal value is used to detect foreign matter between the work and the bottom surface. A press-fitting device characterized in that the presence / absence is determined. 4. A press-fitting device according to claim 2, wherein the tip jig attached to the press-fitting rod, the holder and the piezoelectric actuator are made lighter in weight to increase the resonance frequency. 5. A tip jig, a holder, and a piezoelectric actuator 3 attached to a press-fitting lot according to claim 2.
A press-fitting device, characterized in that the mass of the inertial weight is made sufficiently larger than the total mass of the points, and the tip end vibration reaction force at the time of press-fitting is absorbed by the inertial energy of the inertial weight. 6. The piezoelectric actuator according to claim 2, wherein the vibration frequency of the piezoelectric actuator is automatically changed from a low frequency range to a high frequency range, and a resonance frequency during that period is detected from the input power, and the resonance frequency is maintained. Press-fitting device. 7. A press-fitting device according to claim 2, wherein it is detected that the resonance frequency of the piezoelectric actuator changes in accordance with a change in press-fitting load, and is automatically corrected and maintained at an optimum frequency. 8. The piezoelectric actuator according to claim 2, wherein the piezoelectric actuator is always driven at a resonance frequency to reduce static friction due to press-fitting with a minimum energy, and press-fit with a small pressure that does not distort the work. Press-fitting device. 9. The press-fitting according to claim 2, wherein when the press-fitted work bottoms out, it is possible to determine that the bottoming work is completed by utilizing the fact that the resonance frequency of the piezoelectric actuator largely changes. apparatus. 10. The tip jig according to claim 2 is provided with a pressing rod that moves back and forth inside the center, and at least two hooking bodies that extend outward by the forward movement of the pressing rod are rotatably provided on the outer periphery of the pressing rod. A press-fitting device characterized in that a claw formed on the hook body is hooked on a ring-shaped work by expanding the hook body outward.