JP3223778B2 - Friction welding method and friction welding device - Google Patents

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 using frictional heat, and more particularly, to a method for easily managing the phases of the 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
It does not generate light or dust during welding compared to other methods for joining two workpieces, for example, arc welding,
There is an advantage that even if oil adheres to the work, it has almost no effect on the joining strength, and the production efficiency can be improved. The operation steps will be described with reference to FIG. by the way,
FIG. 12 shows the relationship between the number of rotations of the work that changes as the friction welding process proceeds, the feed speed of the work in the horizontal direction (Y direction), and the position in the Y direction that changes as the feed amount increases.

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

A friction pressure welding apparatus for carrying out the friction pressure welding method comprises clamping one of a pair of works and fixing the other to a chuck provided on a rotary drive means.
They are arranged coaxially. 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 work and the feed amount in the horizontal direction, etc. are mainly performed to generate frictional heat at a joint between the works and press the joint together. Does not appropriately detect the softened state in the above and make fine adjustments. That is, in the friction welding step, the control content is set in advance based on experimentally obtained data, and the welding step proceeds irrespective of the actual softened state at the joint between the two works.
As a conventional example of the friction welding apparatus, 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 needs to
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 workpiece with the above-described friction welding apparatus has the following problems. That is, since the friction welding apparatus itself does not have a means for detecting the progress of softening at the joint between the two workpieces, it is difficult to perform an optimal operation control for each single welding operation. It was not easy to increase the speed in units and to increase the versatility for different workpieces. In addition, it is necessary to detect the timing at which the above-described process is started by an external sensor, and the timing tends to vary depending on the detection accuracy of the external sensor and the like, and it has been difficult to stabilize the quality.

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

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to grasp the progress of softening at a joint portion between two workpieces at every press-welding operation and to determine the progress of the softening. Another object of the present invention is to adjust the rotation and feed of the workpieces to facilitate the phase management between the workpieces.

[0009]

Means according to the present invention for solving the above-mentioned problems are as follows: a pair of works arranged opposite to each other is pressed relative to each other by applying relative rotation to generate frictional heat at a joint between the two works; A friction welding method for welding a joint portion between the two works softened by the frictional heat, wherein the pair of works have a desired phase angle when the softening of the joint portion is advanced and a desired softened state is obtained. Calculating a deceleration curve of the relative rotation speed for stopping at step (a), 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 of the pair of works becomes a state suitable for applying the upset force, the phases of the works are accurately determined, and the upset force is applied. Complete the crimping operation.

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 made smaller than the feed torque of the work in the step of promoting the softening of the joint. Is desirable.

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

According to another aspect of the present invention, there is provided a friction pressure welding apparatus for fixing a pair of workpieces facing each other, a rotation driving means for relatively rotating the pair of workpieces, And a parallel moving means for pressing the rotary drive means and a servo motor as a power source of the parallel moving means, and a control means for grasping a progress state of the pressing process of the work from a load current value of the servo motor. Further, the control means can simultaneously control the rotation speed and the rotation angle of the rotary drive means and the feed amount and the feed torque of the parallel movement means in accordance with the progress of softening of the joint. It is characterized by being.

In the present invention, the progress of the pressing process of the work is grasped by the control means, so that the optimum pressing process is performed for each friction welding operation, and the rotation of the work by the rotation driving means is performed. By simultaneously controlling the speed and the rotation angle and the feed amount and the feed torque of the parallel moving means, accurate phase setting and size setting of the workpieces are performed.

[0015]

Embodiments of the present invention will be described below with reference to the accompanying drawings. First, FIG. 2 shows and describes a friction welding apparatus according to an embodiment of the present invention. This friction welding apparatus 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 main shaft 4 is rotatably supported by the main shaft 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. Furthermore, the tip of the main shaft 4 has a chuck 10 is mounted, it is possible to fix the workpiece W ₁ to the spindle 4.

The spindle unit 2 is attached to the equipment base 1 via a linear guide 11, and is movable in the axial direction of the spindle 4 (Y direction). 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 The driving force guides the main 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 apparatus of FIG. Servo motor for rotation 7
Each of the press-contact servomotor 13 and the press-contact servomotor 13 is provided with a rotation servo driver 16 and a press-contact servo driver 17, and has a friction press-contact controller 18 as control means for these. 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 such a construction, the pressure welding servomotor is controlled by the friction pressure welding controller 18 which is a control means.
From 13 load current values, the progress of softening at the joint between the works W ₁ and W ₂ can be grasped. Its approach is to grasp the optimum load current value in the feed amount with a workpiece W ₁ (the proportion in the feed torque) empirically, and the magnitude of the measured values for the optimal load current value, 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 and feeds the rotation servomotor 7.
And the feed amount and feed torque of the press-contact servomotor 13 are simultaneously controlled.

Next, a process of performing friction welding by the friction welding apparatus having the above-described configuration 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
It grasps from the load current value of the press-contact servomotor 13 and feeds it back to the control of each servomotor. Incidentally, the load current value is proportional to the load applied to the pressure servomotor 13, the load is proportional to the feed torque applied to the joint portion of the workpiece W _1, W _2. Therefore, in the embodiment of the present invention, as shown in FIG. 1, the relationship between the number of rotations of the work, the feed amount in the horizontal direction of the work, and the feed torque, which is changed with the progress of the friction welding process, is grasped. Feedback to motor control. Therefore, in the following description, the description of the flowcharts of FIGS. 4 to 10 will be sequentially incorporated while mainly referring to FIG. 4 to 6 show the contents related to a control system (hereinafter, referred to as a rotation control system) of the relative rotational speed of the work shown in the upper part of FIG. FIGS. 7 to 10 show the contents related to a pressure contact torque control system (hereinafter, referred to as a torque control system) shown in the lower part of FIG.

As shown in FIG. 1, in the friction welding step, a step of starting friction welding (step 0), a step of proceeding softening until a desired softened state is obtained at a joint portion of the work (step 1), When the desired softened state in the part is obtained,
A step of calculating a deceleration curve of the relative rotational speed of the work for stopping the pair of works at a desired phase angle (step 2); and a step of stopping the relative rotation of the work along the deceleration curve (step 3). And the step of applying an upset force (step 4).

Here, step 0 is described with reference to FIGS.
This will be described with reference to FIG. First, in the rotation control system shown in FIG.
1). Perform home return to determine the operation reference point (00
2). If homing is not performed, the operation is stopped (003). Next, complete the work setting (0
04). Then, it waits for a friction welding start instruction (005), and upon receiving the start instruction, 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,
The work feed torque H = β is designated (010). PID
By the control, the 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 press-contact servomotor 13 (FIG. 3) is monitored (012). Incidentally, when the workpiece W ₁ and the workpiece W ₂ are in contact as shown in FIG. 1 (Y ₀ position), the load is temporarily increased by a frictional force of the joint surface, sliding the softening starts the bonding surface caused by frictional heat Thus, the load becomes constant again. Therefore, the feed torque H = α at the time when the load increases is defined as the workpiece contact determination torque,
Feeding is continued until feed torque H = α is detected (013).

Next, step 1 for promoting the softening of the workpiece will be described with reference to FIGS. 1, 3, 4 and 8. First, in the torque control system shown in FIG. 8, data corresponding to the feed position Y = Y ₀ at the time when the feed torque H = α is detected is input as pulse data of the encoder 21 from the press-contact servo driver 17 ( 101), to identify and stored by calculating the contact position Y ₀ of the workpiece (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). Further, even after the workpiece comes into contact, PID control is performed to maintain the workpiece feed torque H = β (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 defined as a 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). And at the time when a Y = Y _1, and outputs a deceleration position signal (108).

In the rotation control system shown in FIG.
After the pressure contact start signal is output at step (008), the value of the feed position Y is received from the torque control system shown in FIG.
9), the deceleration start position determined whether reached Y ₁ (
110).

Next, step 2 for calculating the deceleration curve of the relative rotational speed of the work will be described with reference to FIGS.
Perform based on. In the (110) Step 1 shown in FIG. 4, when the feed position of the workpiece has reached the deceleration start position Y ₁ is confirmed, the rotation control system illustrated in FIG. 5, the deceleration operation for stopping the relative rotation Is started (201). And
A deceleration start signal is output to the torque control system (202), and Z-phase data of the rotation servomotor 7 (a signal representing the home 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 from the Z-phase position to the target position (angle) (I = the number of rotations from the start to the stop of deceleration + the target position (angle)) is obtained (205).

Next, count number data I to the target position
Calculation based on the result of, as the deceleration curve of the relative rotational speed of the workpiece to obtain the deceleration curve U 3D, rotation of the workpiece W ₁ is to slow, performs PID control along the deceleration curve U (206) . The deceleration curve U has a curve as shown in FIG. 11, and can be obtained from the following equation as an example. Here, assuming that the time point when the vehicle reaches the deceleration start position Y ₁ 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: Workpiece rotation speed T: Deceleration stop time A: Relative rotation speed at the start of deceleration R: Constant calculated from A and T In addition, when the rotation speed ω is integrated over the elapsed time t = 0 to T, an arbitrary rotation speed (for example, 8 rotations) + a phase angle is obtained.

Returning again to the description of the flowchart, during the deceleration control along the three-dimensional deceleration curve U, the rotation servo driver 16 sends the pulse count data P of the encoder 20 from the encoder 20.
Is input (207), and comparison is performed 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 falls within the allowable error range, the current position (angle) X of the rotary servomotor 7 is calculated from the information of the rotary servo driver (209), and the current position X is set to the target position _Xa.
Monitoring is continued until the value falls within the tolerance b of
0). Then, when the value falls within the allowable error range, the process proceeds to step 3 described below.

Next, step 3 for stopping the relative rotation of the work along the deceleration curve U is described in FIGS. 1, 6 and 9.
It will be described based on. The rotation control system illustrated in FIG. 6, the current position X of the angle of the workpiece, it is confirmed to be within the allowable error range b of the target position X _a (210), in the rotation control system shown in FIG. 6 Then, a disc brake (8 and 9 in FIG. 2) operation command is output to the main shaft 4 to prevent a phase shift, and further a positioning completion signal is output to the torque control system (302) to control the rotation control system. Exit (30
3). By the way, the feed position at the time when the relative rotation of the work stops is defined as 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 in step 2 is received (304), the workpiece feed torque H = β in step 1 is obtained. Small feed torque H =
An instruction to change the torque to δ is issued (305). Here, the reason for reducing the feed torque is as follows. That is,
In step 3 for 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 progress of softening and the work It is necessary to balance with the feed amount. Therefore, the feed torque H = δ
It is assumed that the value of can prevent the change of the softened state due to the temperature change of the joint and suppress the fluctuation of the surface pressure at the joint, thereby stabilizing the degree of adhesion of the joint until the application of the upset force.

Then, while feeding back the load current value of the press-contact control motor 13, torque control is performed by PID control, the feed torque of the work is maintained at H = δ, and the feed of the work is continued (306). When a positioning completion signal is received from the torque control system (307), when positioning is completed (3)
08), and proceed to the step of applying the upset force described below.

Next, step 4 of applying an upset force to the work will be described with reference to FIGS. 1 and 10. Figure
In the torque control system shown in 10, at the feed position Y ₂ at the time the relative rotation of the workpiece is stopped, the torque-up instruction to the feed torque H = K _p corresponding to the upset force (401). The pressure control motor 13 is controlled by PI control.
Performs torque control while feeding back the load current value to the torque up to the feed torque H = K _p. In this case, even if the if H> K _p, since particular problem that does not occur is known from experience, the torque down instruction during H> K _p is not performed. Then, the temperature of the joint portion of the workpieces decreases, and the pair of workpieces 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). A comparison is made as to whether the feed position Y at this time satisfies Y ≧ B + g (B = B ₀ + Y ₀ ) (iii) B: target feed position B ₀ : constant g: allowable error (404). Then, when the comparison condition is satisfied, data input indicating that the desired dimensional accuracy has been obtained is performed (406), and the friction welding operation 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 workpieces during friction welding. The operation and effect obtained from the embodiment of the present invention having the above configuration are as follows. In the friction welding process, the rotation servomotor 7 and the pressure servomotor 13
The progress of the pressure welding process of the work was grasped from the load current value of the work, and it was fed back to the operation control of each motor, and the softened state at the joint of the pair of works became a state suitable for applying the upset force. At this point, it is possible to perform accurate phase setting 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 PI is decelerated along the deceleration curve U so that the rotation of the work W ₁ is decelerated.
Since the D control is performed, it is possible to perform accurate phase detection. Moreover, in the step of reducing the rotational speed of the workpiece W _1, it is taken into account the partial amount of heat generation is decreased, the feed torque H of the workpiece is decreased from β to [delta], progressive softening at the junction of the pair of works and so balance the feed rate of the workpiece, prevent variations in the softened state due to the temperature change of the junction, by suppressing the surface pressure variations at the junction, to apply a feed torque K _P corresponding to upset force, It is possible to stabilize the degree of adhesion of the joint.
Therefore, a product with high dimensional accuracy can be obtained.

[0036]

As described above, the present invention has the following effects. That is, in the step of welding the pair of works by the friction welding method, the softening of the joining portion is advanced, and at the time when a desired softened state is obtained, the relative work for stopping the pair of works at a desired phase angle is achieved. After calculating the deceleration curve of the rotation speed and stopping the relative rotation of the work along the deceleration curve, each step of applying an upset force is included, so that the softened state at the joint between the pair of works applies the upset force. When the state becomes suitable for the above, by reducing the relative rotational speed of the work along the deceleration curve, it is possible to perform accurate phase setting between the works.

Then, at the time when the phase setting is completed, an upsetting force is further applied to complete the pressure welding operation, so that the phase of the product can be accurately set. Therefore, it is not necessary to use a mechanical lock mechanism, to prevent the size of the friction welding device from being increased, and to make large-scale equipment changes every time the work is changed, in order to accurately phase out the works as in the past. Is also gone. Therefore, the shape, material, and the like when changing the workpiece are not restricted, and the unit cost of the product can be reduced.

In addition, 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. The balance between the progress of the workpiece and the feed rate of the workpiece, preventing the change in the softened state due to the temperature change of the joint, and suppressing the surface pressure fluctuation at the joint, stabilizes the adhesion of the joint until the upset force is applied It is possible to do. Therefore, a product with high dimensional accuracy can be obtained.

Further, the friction welding apparatus according to the present invention grasps the progress state of the workpiece welding process from the load current value of the servo motor which is the power source of the pair of workpiece rotation drive means and parallel movement means. Furthermore, since feedback is provided to the operation control, when the softened state at the joint of the pair of works becomes a state suitable for applying the upset force, it is possible to complete accurate phase setting between the works,
Further, by applying an upset force and terminating the pressure welding operation, a product having high dimensional accuracy can be obtained.

[Brief description of the drawings]

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

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

FIG. 3 is a configuration diagram of control means of the friction welding device shown in FIG. 2;

FIG. 4 is a flowchart illustrating a control procedure in a control system of a relative rotational speed of a work in the friction welding method according to the embodiment of the present invention.

FIG. 5 is a flowchart continued from FIG. 4;

FIG. 6 is a flowchart continued from FIG. 5;

FIG. 7 is a flowchart showing a control procedure in a control system of a press-contact torque of a work in the friction press-contact method according to the embodiment of the present invention.

FIG. 8 is a flowchart continued from FIG. 7;

FIG. 9 is a flowchart continued from FIG. 8;

FIG. 10 is a flowchart continued from FIG. 9;

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

FIG. 12 is a graph showing the rotational speed of the work, the Y-direction position that changes with an increase in the feed amount, and how the feed speed changes in each step of the conventional friction welding method.

[Explanation of symbols]

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

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-53-43056 (JP, A) JP-A-53-147652 (JP, A) JP-A-51-45651 (JP, A) JP-A-61-456 283479 (JP, A) JP-A-3-124384 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23K 20/12

Claims (3)

(57) [Claims] 1. A pair of works arranged opposite to each other are given relative rotation and pressed against each other to generate frictional heat at a joint between the two works.
A friction welding method for welding a joint portion of the two works softened by the frictional heat, wherein softening of the joint portion is advanced,
At the time when the desired softened state is obtained, a deceleration curve of the relative rotational speed for stopping the pair of workpieces at a desired phase angle is calculated, and after the relative rotation of the workpiece is stopped along the deceleration curve, And a step of applying an upset force. 2. The work feed torque in the step of stopping the relative rotation of the work along the deceleration curve is smaller than the work feed torque in the step of promoting the softening of the joint. The friction welding method according to claim 1, wherein the friction welding is performed. 3. A fixing device for arranging a pair of works facing each other, a rotation driving means for giving relative rotation to the pair of works, and a parallel moving means for pressing the pair of works into contact with each other. Each servo motor is used as a power source of the parallel moving means, and a control means for grasping a progress state of the pressing process of the work from a load current value of the servo motor is further provided. A friction welding apparatus, wherein a rotation speed and a rotation angle of the rotation drive unit and a feed amount and a feed torque of the parallel movement unit can be simultaneously controlled in accordance with a traveling state.