JPH09174260A - Friction pressure welding method and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate phase control between works. SOLUTION: In welding a pair of works by friction pressure welding, a phase between the works is accurately determined. As the procedure, steps are provided such that softening is promoted for the joining part of the pair of works (step 1), that, upon obtaining a desired softened state, in order for the pair of works to stop at a desired phase angle, a deceleration curve U is calculated from the relative revolution speed (a) of the works (step 2), and that the relative revolution of the works is stopped along the deceleration curve U (step 3), and a step for adding a feed torque KP commensurate with an upset force. In addition, in comparison with the feed torque βof the works in the step for promoting the softening of the joining part, the feed torque δ of the works is reduced in the step for stopping the relative revolution of the works along the deceleration curve. With this method, the need for deciding, the phase of the work by a mechanical lock mechanism is obviated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction welding method for welding a pair of works by using frictional heat, and more particularly to a method for facilitating phase control between works when welding is completed.

[0002]

2. Description of the Related Art A friction welding method is often used as a method for joining two works. This friction welding method is 2
Compared to other methods for joining two workpieces, such as arc welding, does not generate light or dust during welding,
Even if the oil adheres to the work, there is an advantage that the bonding strength is hardly affected, and the production efficiency can be improved. The working process will be described with reference to FIG. by the way,
FIG. 12 shows the relationship between the rotational speed of the work, which is changed with the progress of the friction welding process, the feed speed of the work in the horizontal direction (Y direction), and the Y-direction position, which is changed as the feed amount is increased.

First, relative rotation is applied to a work, and when it reaches a predetermined frictional rotation speed, the work is started to be fed (step). Then, the works are brought into pressure contact with each other, the feed rate is adjusted to be constant so as to maintain a predetermined pressure, and the joint part of the two works is softened by the friction heat generated at the joint part. Then, the feed amount of the work is increased as the softening of the joint progresses, and the softening progresses to a desired state described later (step). When the softening progresses to a desired state, that is, to a state optimal for applying the upset force, braking is applied to stop the rotation of the work, and at the same time, the feed rate is maximized to pressurize the upset force (step). The joints between the workpieces are integrated so as to fit into each other, and welding is completed. At this time, the relative rotation and feed of the work are completely stopped (step).

A friction welding device for carrying out the above friction welding method is such that one of a pair of works is clamped and the other is fixed to a chuck provided on a rotation driving means.
It is arranged to be coaxial. Then, while rotating one of the workpieces, the workpiece can be moved in parallel so as to be brought into contact with the other workpiece. The rotation drive means and the parallel movement means each use a motor or the like as a power source. The control of the number of rotations of the workpieces and the feed amount in the horizontal direction is mainly performed to cause frictional heat generation in the joints between the workpieces and press-contact the joints. It does not detect the softened state in the above as appropriate and make a fine adjustment. That is, in the friction pressure welding process, the control content is set in advance based on the data obtained experimentally, and the pressure welding process proceeds regardless of the actual softened state at the joint between the two works.
As a conventional example of the friction welding device, the details thereof are disclosed in Japanese Utility Model Laid-Open No. 3-85183.

When it is necessary to provide a predetermined phase in the positional relationship between the two works, the friction welding device is provided with
A dedicated mechanical lock mechanism is provided for each type of work, and a desired phase is obtained by the operation of the mechanical lock mechanism.

[0006]

However, the method of friction-welding a work with the above-mentioned friction-welding device has the following problems. That is, since the friction welding device itself is not provided with any means for detecting the progress of softening at the joint between two workpieces, it is difficult to perform optimum operation control for each welding operation, and the lot welding process is not performed. It was not easy to increase the speed in units and increase versatility for different works. Further, it is necessary to detect the timing of starting the above process with an external sensor, and the timing is likely to vary depending on the detection accuracy of the external sensor, etc., and it is difficult to stabilize the quality.

Further, when it is necessary to provide a predetermined phase in the positional relationship between two works, it is necessary to provide a dedicated mechanical lock mechanism for each type of work in the friction welding device. It became larger and lost versatility. Therefore, when the work is changed, various restrictions such as the work shape and the material are imposed, and it is necessary to significantly change the equipment in order to eliminate the conditional restrictions.

The present invention has been made in view of the above problems, and an object of the present invention is to grasp the progress of softening at the joining portion of two works for each pressure welding operation and to determine the progress of softening based on the progress. First, the rotation and feed of the works are adjusted to facilitate phase control between the works.

[0009]

Means for Solving the Problems According to the present invention for solving the above-mentioned problems, a pair of works arranged opposite to each other are pressed against each other by relative rotation, and frictional heat is generated at the joint between the two works. A friction welding method for welding the joints of the two works softened by the friction heat, wherein the pair of works has a desired phase angle when the softening of the joints is advanced and a desired softened state is obtained. It is characterized by including a step of calculating a deceleration curve of the relative rotation speed for stopping at, stopping the relative rotation of the work along the deceleration curve, and then applying an upset force.

With this configuration, when the softened state at the joint between the pair of works becomes a state suitable for applying the upsetting force, the works are accurately phased, and the upsetting force is further applied. Complete the pressure welding work.

In the present invention, the feed torque of the work in the step of stopping the relative rotation of the work along the deceleration curve is smaller than the feed torque of the work in the step of advancing the softening of the joint. Is desirable.

In the step of stopping the relative rotation of the work along the deceleration curve, the amount of heat generated by the relative rotation of the work is reduced. Therefore, the feed torque of the work is reduced and the softening of the joint between the pair of works is promoted. Balance with the work feed amount.

Further, in the friction welding device according to the present invention for solving the above problems, a fixing means for arranging a pair of works facing each other, a rotation driving means for giving a relative rotation to the pair of works, and the pair of works. And a parallel moving means for press-contacting each other, each of which uses a servo motor as a power source of the rotation driving means and the parallel moving means, and grasps the progress state of the press-contacting process of the work from the load current value of the servo motor. Further, the control means can simultaneously control the rotation speed and the rotation angle of the rotation driving means and the feed amount and the feed torque of the parallel moving means in accordance with the progress of softening of the joint portion. Is characterized in that.

According to the present invention, the progress state of the work piece pressure contact process is grasped by the control means, so that the optimum pressure contact process progresses for each frictional pressure contact work, and the rotation drive means rotates the work piece. By simultaneously controlling the speed and rotation angle and the feed amount and feed torque of the parallel moving means, accurate phasing and dimensioning of the works are performed.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. First, a friction welding device according to an embodiment of the present invention is shown in FIG. 2 and described. This friction welding device has a spindle unit 2 and a clamp 3 on an equipment base 1. The pair of works W ₁ and W ₂ are attached to the spindle unit 2 and the clamp 3, respectively.

The spindle 4 is rotatably supported by the spindle unit 2. The spindle 4 is located inside the spindle unit 2.
It is drivingly connected to a rotation servomotor 7 via gears 5 and 6. Further, a brake disk 8 is attached to the main shaft 4, and the brake can be applied to the main shaft 4 by operating the brake caliper 9. Further, a chuck 10 is attached to the tip of the spindle 4, so that the work W ₁ can be fixed to the spindle 4.

The spindle unit 2 is attached to the equipment base 1 via a linear guide 11 and is movable in parallel in the axial direction (Y direction) of the spindle 4. Further, the spindle unit 2 has an arm 12 projecting into the equipment base 1, a pressure contact feed shaft 14 driven by a pressure contact servomotor 13 is inserted into the arm 12, and the pressure contact feed shaft 14 is rotated, An arm is formed by a thread groove formed in the shaft.
Generates propulsion between 12 This propulsive force drives and guides the spindle unit 2 in the Y direction. Between the spindle unit 2 and equipment base 1 provided with a stroke sensor 15, 15a, the spindle unit 2 (i.e., the workpiece W ₁₎ feed rate and feeding amount (or current position) and can be measured.

The clamp 3 includes a y-axis clamp 3a for positioning the workpiece W ₂ in the axial direction of the main shaft 4, and z-axis clamp 3b for the positioning in the lateral direction with respect to said axis, the positioning in the vertical direction relative to said axis X-axis clamp 3c. Then, each axis clamp by appropriately adjusting, in the work W ₁ coaxially to the fixed to the main shaft 4, it is possible to arrange the workpiece W _2.

FIG. 3 shows the structure of the control means used in the friction welding device of FIG. Servo motor for rotation 7
A rotary servo driver 16 and a pressure servo driver 17 are provided for each of the press servo motor 13 and the press servo motor 13, and a friction press controller 18 is provided as a control means for these. Further, the friction welding controller 18 is in communication with a host controller (PLC) 19 that controls the entire equipment. In the figure, 20 and 21 are encoders.

With this structure, the friction welding controller 18 serving as the control means controls the servomotor for pressure welding.
From the load current value of 13, it is possible to grasp the progressing state of softening at the joint between the works W ₁ and W ₂ . The method empirically grasps the optimum load current value (proportional to the feed torque) at a certain feed amount of the work W ₁ , and compares the actual measured value with the optimum load current value and the feed amount at that time. Therefore, the quality of the softened state is determined.
Further, the friction welding controller 18 feeds back the progress of the softening of the joint portion, and the servomotor 7 for rotation is fed back.
The rotation speed and the rotation angle of the above are simultaneously controlled, and the feed amount and the feed torque of the pressure welding servo motor 13 are simultaneously controlled.

Next, the step of performing friction welding with the friction welding apparatus having the above-mentioned structure will be described with reference to FIGS. 1 and 4 to 10. As described above, in the embodiment of the present invention,
The progress of softening at the joint between the works W ₁ and W ₂ is
It is grasped from the load current value of the servomotor for pressure welding 13 and fed back to the control of each servomotor. By the way, the load current value is proportional to the load applied to the press-contact servomotor 13, and the load is proportional to the feed torque applied to the joint between the works W ₁ and W ₂ . Therefore, in the embodiment of the present invention, as shown in FIG. 1, the relationship between the rotation number of the work, the feed amount of the work in the horizontal direction, and the feed torque, which are changed with the progress of the friction welding process, is grasped, and each servo is grasped. It is feeding back to the motor control. Therefore, in the following description, the description of the flowcharts of FIGS. 4 to 10 will be sequentially incorporated mainly with reference to FIG. 4 to 6 show the contents relating to the control system (hereinafter referred to as the rotation control system) for the relative rotation speed of the work shown in the upper part of FIG. 7 to 10 show the contents relating to the pressure contact torque control system (hereinafter referred to as the torque control system) shown in the lower part of FIG.

As shown in FIG. 1, in the friction welding process, a step of starting friction welding (step 0), a step of advancing softening until a desired softened state is obtained at a welded portion of the work (step 1), the welding is performed. When the desired softened state in the part is obtained,
Calculating a deceleration curve of the relative rotation speed of the work for stopping the pair of works at a desired phase angle (step 2); stopping the relative rotation of the work along the deceleration curve (step 3) , Step of applying upset force (step 4).

Here, the step 0 will be described with reference to FIGS.
This will be described with reference to FIG. First, in the rotation control system shown in FIG. 4, the setting condition for each work is input (00
1). Perform home return to set the operation reference point (00
2). If no return to origin is performed, stop the work (003). Then complete the work setting (0
04). Then, it waits for an instruction to start friction welding (005), and when receiving the instruction to start friction welding, it starts friction welding (006). And PID control (PID: Proportional Integral and
Derivative), the relative rotation speed ω of the work is proportionally accelerated to the friction rotation heat generation speed a (a = 2000 rpm) (007). Then, a pressure welding start signal is output to the torque control system (008).

At this point, as shown in FIG. 7, the feeding of the work in the torque control system is started (009). First,
Designate the work feed torque H = β (010). PID
By the control, torque control is performed while feeding back the load current value of the press contact control motor 13, and the torque is increased to H = β (011). The load current value of the servomotor for pressure welding 13 (FIG. 3) is monitored (012). By the way, when the work W ₁ and the work W ₂ come into contact with each other as shown in FIG. 1 (position Y ₀ ), the load temporarily increases due to the frictional force of the joint surface, and slippage occurs when the joint surface begins to soften due to frictional heat. Then, the load becomes constant again. Therefore, the feed torque H = α at the time when this load increases is defined as the workpiece contact determination torque,
The feeding is continued until the feeding torque H = α is detected (013).

Next, step 1 for promoting the softening of the work will be described with reference to FIGS. 1, 3, 4, and 8. First, in the torque control system shown in FIG. 8, the data corresponding to the feed position Y = Y ₀ at the time when the feed torque H = α is detected is input from the pressure contact servo driver 17 as the pulse data of the encoder 21 ( 101), the contact position Y _{0 of the} work is specified by calculation and stored (102). Then, the deceleration start position Y ₁ is obtained from Y ₁ = M + Y ₀ (M is a feed amount during heat generation and is a constant) (10
3). In addition, PID control is performed in order to maintain the work feed torque H = β even after the work contacts (10
Four). Then, the feed position Y is continuously monitored until the desired softened state of the work is obtained (105). Here, the feed position for obtaining the desired softened state of the work is set to the deceleration start position Y.
_1, and enter the value of the deceleration start position Y ₁ (106), compared to the current feed position Y, continues monitoring until Y = Y ₁ (107). Then, when Y = Y ₁ , a deceleration position signal is output (108).

Further, in the rotation control system of FIG. 4, step 0
After the pressure welding start signal is output at (008), the value of the feed position Y is received from the torque control system shown in FIG.
9), it is judged whether or not the deceleration start position Y ₁ is reached (
110).

Next, step 2 for calculating the deceleration curve of the relative rotation speed of the work will be described with reference to FIGS. 1, 3 and 5.
Perform based on. When it is confirmed that the feed position of the work reaches the deceleration start position Y ₁ in (110) of step 1 shown in FIG. 4, the deceleration work for stopping the relative rotation in the rotation control system shown in FIG. Is started (201). And
A deceleration start signal is output to the torque control system (202), Z phase data of the rotation servo motor 7 (a signal indicating the origin position detected by the encoder 20) is input from the rotation servo driver 16 (203), When the Z-phase signal is detected (204),
Count number data I (I = number of rotations from deceleration start to stop + target position (angle)) from the Z-phase position to the target position (angle) is obtained (205).

Next, the count number data I up to the target position
A three-dimensional deceleration curve U is obtained as a deceleration curve of the relative rotation speed of the work based on the calculation result of, and PID control is performed so that the rotation of the work W ₁ is decelerated along the deceleration curve U (206). . This deceleration curve U has a curve as shown in FIG. 11, and as an example thereof, it can be obtained from the following mathematical formula. Here, assuming that the time when the deceleration start position Y ₁ is reached is the elapsed time t = 0, ω = Rt ³ + A (0 ≦ t <1/2 T) (i) ω = R (t−T) ³ (1/2 T ≦ t <T) (ii) At this time, ω: rotation speed of work T: deceleration stop time A: relative rotation speed at deceleration start R: constant calculated from A and T Further, when the rotation speed ω is integrated during the elapsed time t = 0 to T, an arbitrary rotation speed (for example, 8 rotations) + phase angle is obtained.

Returning to the explanation of the flow chart again, during the deceleration control along the three-dimensional deceleration curve U, the pulse count data P from the rotary servo driver 16 to the encoder 20 is obtained.
(207) and compare until the difference between the operation data I and the pulse count data P falls within the allowable error range (20
8). If this difference is within the allowable error range, the current position (angle) X of the rotation servo motor 7 is calculated from the information of the rotation servo driver (209), and the current position X is set to the target position X _a.
Continue monitoring until it falls within the tolerance b of (21
0). Then, when it is within the allowable error range, the process proceeds to step 3 described below.

Next, the step 3 of stopping the relative rotation of the work along the deceleration curve U will be described with reference to FIGS.
It will be described based on. In the rotation control system shown in FIG. 6, when it is confirmed that the current position X related to the angle of the work is within the allowable error b of the target position X _a (210), the rotation control system shown in FIG. , Outputs a disc brake (8 and 9 in FIG. 2) operation command to the spindle 4 to prevent phase shift, and further outputs a positioning completion signal to the torque control system (302) to control the rotation control system. End (30
3). By the way, the feed position at the time when the relative rotation of the work is stopped is Y ₂ (FIG. 1).

In the torque control system shown in FIG. 9, when the deceleration start signal (202) output from the rotation control system is received in step 2 (304), the work feed torque H = β in step 1 Small feed torque H =
Instruct to change the torque to δ (305). Here, the reason for reducing the feed torque is as follows. That is,
In step 3 in which the relative rotation of the work is stopped along the deceleration curve, the amount of heat generated by the relative rotation of the work is reduced. Therefore, the feed torque of the work is reduced, and the progress of softening and the work It is necessary to balance with the feed amount. Therefore, the feed torque H = δ
The value of is to prevent the softened state from changing due to the temperature change of the joint and suppress the surface pressure fluctuation at the joint, thereby making it possible to stabilize the adhesion of the joint until the upset force is applied.

Then, while feeding back the load current value of the pressure contact control motor 13, torque control is performed by PID control to keep the work feed torque at H = δ and continue the work feed (306). When the positioning completion signal is received from the torque control system (307) and positioning is completed (3
08), and shifts to the step of applying upset force described later.

Next, step 4 for applying the upsetting force to the work will be described with reference to FIGS. 1 and 10. Figure
In the torque control system shown in FIG. 10, at the feed position Y ₂ at the time when the relative rotation of the workpiece is stopped, a torque up instruction to feed torque H = K _p corresponding to the upset force is issued (401). And the pressure control motor 13 by PI control
The torque control is performed while feeding back the load current value of 1 to increase the feed torque to H = K _p . At this time, it is known from experience that even if H> K _p , no particular problem will occur, so the torque down instruction is not issued when H> K _p . Then, the temperature of the joint portion of the works is lowered, and the pair of works W ₁ and W ₂ are welded. The feed position is calculated from the pulse data of the encoder 21 up to this point (403). The feed position Y at this time is: Y ≧ B + g (B = B ₀ + Y ₀ ) ... (iii) B: Target feed position B ₀ : Constant g: It is compared whether or not the tolerance is satisfied (404). When the comparison condition is satisfied, the data indicating that the desired dimensional accuracy has been obtained is input (406), and the friction welding work is completed (4).
07). If the comparison condition is not satisfied in (404), it is recognized as a defective product and an error is displayed (405).

As described above, it is possible to provide a predetermined phase in the positional relationship between the pair of works when the friction welding is performed. The operation and effect obtained from the embodiment of the present invention having the above configuration is as follows. In the friction welding process, the rotation servomotor 7 and the pressure welding servomotor 13
The progress state of the work piece pressure welding process is grasped from the load current value of, and it is fed back to the operation control of each motor, and the softened state at the joint part of the pair of work pieces becomes a state suitable for applying the upset force. At this point, it is possible to perform accurate phase alignment between the works.

Further, in order to stop the rotation of the work W ₁ at a desired phase, a three-dimensional deceleration curve U is obtained, and the rotation of the work W ₁ is decelerated along the deceleration curve U so that the PI
Since the D control is performed, it is possible to perform the phase extraction with high accuracy. Moreover, in the step of decelerating the rotation speed of the work W ₁ , the feed torque H of the work is reduced from β to δ in consideration of the decrease in the heat generation amount, and the softening progresses in the joint portion of the pair of works. And the feed amount of the work are balanced, the change in the softened state due to the temperature change of the joint is prevented, and the fluctuation of the surface pressure at the joint is suppressed, until the feed torque K _P corresponding to the upset force is applied. It is possible to stabilize the adhesion of the joint.
Therefore, a product with high dimensional accuracy can be obtained.

[0036]

According to the present invention, the following effects are obtained. That is, in the step of welding a pair of works by a friction welding method, the relative softness of the pair of works is stopped at a desired phase angle when the softening of the joint is advanced and a desired softened state is obtained. After calculating the deceleration curve of the rotation speed and stopping the relative rotation of the workpiece along the deceleration curve, each step of applying the upset force is included, so that the softened state at the joint portion of the pair of works applies the upset force. When it becomes a state suitable for the above, the relative rotation speed of the works is reduced along the deceleration curve, whereby the work can be accurately phased.

Then, when the phase setting is completed, the upsetting force is further applied to complete the pressure welding work, so that the phase of the product can be accurately obtained. Therefore, it is not necessary to use a mechanical lock mechanism to accurately phase the workpieces as in the conventional case, it is necessary to prevent the friction welding device from increasing in size, and it is necessary to significantly change the equipment every time the workpiece is changed. Also disappears. Therefore, the shape, material, etc. when changing the work are not restricted, and the product unit price can be kept low.

Moreover, in the step of stopping the relative rotation of the work along the deceleration curve, the heat generation amount due to the relative rotation of the work is reduced, so that the feed torque of the work is reduced and the joining portion of the pair of works is softened. Balances the progress of welding and the feed amount of the work, prevents changes in the softening state due to temperature changes at the joint, and suppresses surface pressure fluctuations at the joint, thereby stabilizing the adhesion of the joint until the upset force is applied. It becomes possible. Therefore, a product with high dimensional accuracy can be obtained.

Further, the friction welding device according to the present invention grasps the progress state of the workpiece pressing process from the load current value of the servo motor which is the power source of the rotation driving means and the parallel moving means of the pair of workpieces, Further, since it is fed back to the operation control, when the softened state in the joint portion of the pair of works becomes a state suitable for applying the upset force, it is possible to complete accurate phase alignment of the works,
By further applying an upset force and ending the pressure welding work, a product with high dimensional accuracy can be obtained.

[Brief description of the drawings]

FIG. 1 is a graph showing changes in a rotation speed of a work, a Y-direction position that changes with an increase in a feed amount, and a transition of a feed torque in each step of a friction welding method according to an embodiment of the present invention.

FIG. 2 is a schematic view showing a friction welding device according to an embodiment of the present invention.

3 is a configuration diagram of a control unit of the friction welding device shown in FIG.

FIG. 4 is a flow chart diagram showing a control procedure in a relative rotation speed control system of a work in the friction welding method according to the embodiment of the present invention.

FIG. 5 is a flow chart diagram continuing from FIG.

FIG. 6 is a flow chart diagram continuing from FIG.

FIG. 7 is a flow chart diagram showing a control procedure in a control system of the pressure welding torque of the work in the friction welding method according to the embodiment of the present invention.

FIG. 8 is a flow chart diagram continuing from FIG.

FIG. 9 is a flow chart diagram continuing from FIG.

FIG. 10 is a flowchart diagram continuing from FIG. 9;

FIG. 11 is a graph showing a deceleration curve of relative rotation speed for stopping relative rotation of the work at a desired phase angle.

FIG. 12 is a graph showing a rotation speed of a work in each step of a conventional friction welding method, a position in the Y direction which changes with an increase in the feed amount, and a change in the feed velocity.

[Explanation of symbols]

B Target feed position K _P Feed torque when upset force is applied U Deceleration curve of relative rotation speed of work Y ₀ Work contact position Y ₁ Work deceleration start position Y ₂ Relative rotation of work in desired phase Feed position at the time of stop a Friction rotation heat generation rate α Work contact judgment feed torque β Feed torque at the step of softening the work δ Feed torque at the step of stopping the relative rotation of the work

Claims (3)

[Claims] 1. A pair of works arranged to face each other is relatively rotated and pressure-contacted to generate friction heat at a joint between both works,
A friction pressure welding method of welding the joints of the two works softened by the friction heat, wherein the softening of the joints is advanced,
When a desired softened state is obtained, a deceleration curve of the relative rotation speed for stopping the pair of works at a desired phase angle is calculated, and after the relative rotation of the works is stopped along the deceleration curve. And a friction welding method, which comprises steps of applying upset force. 2. The feed torque of the work in the step of stopping the relative rotation of the work along the deceleration curve is made smaller than the feed torque of the work in the step of advancing the softening of the joint. The friction welding method according to claim 1. 3. A rotation driving means, comprising: fixing means for arranging a pair of works facing each other; rotation driving means for giving relative rotation to the pair of works; and parallel moving means for pressing the pair of works in pressure contact with each other. Each servo motor is used as a power source of the parallel moving means, and the control means has a control means for grasping the progress state of the pressure welding process of the work from the load current value of the servo motor, and the control means further controls the softening of the joint portion. A friction welding device characterized in that the rotational speed and the rotational angle of the rotary drive means and the feed amount and the feed torque of the parallel moving means can be simultaneously controlled in accordance with the progress state.