JPH0929464A - Friction welding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve dimensional precision of a product and suppress unnecessary generation of burr by visualizing the progress state of softening of a work joining part by a high-speed camera and setting a rotating speed and feed speed of the work based on that. SOLUTION: A work W2 is coaxially arranged with a work W1 fixed on a main spindle 4. By abutting the work W1 , while rotating, on the work W2 , increasing pressure and generating friction heat at the joining part between the work W1 and work W2 , the joining part of both works is softened. Fusion is progressed while softening the joining part, at this time, the feed speed and rotating speed of the work are set so that the graph showing relation between a feed quantity and pressing pressure of the work W1 is found in the optimum joining zone. By picking up the softening state of the joining part with a high speed camera 19, this optimum joining zone is set based on the visualized data. Progressing state of softening is discriminated by the variation in light emitting and color due to heat generation of joining part and the progressing state of deformation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing method for welding a workpiece using frictional heat, and more particularly, to a method for facilitating management of dimensional accuracy after welding.

[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. In the working process, first, one of a pair of workpieces arranged to face each other is rotationally driven and pressed against the other to generate frictional heat at a joint portion of both workpieces,
The frictional heat softens the joint between the two works. Then, the softening is advanced to a desired state, and the upset pressure is further applied while stopping the rotation of the work. Then
The joint portions are integrated and welded by being inlaid with each other.

[0003] In the friction welding apparatus for performing the friction welding, one of a pair of works is clamped and fixed, and the other is fixed to a chuck provided in a rotation driving means, and is 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 are set in advance, and the pressure welding process proceeds regardless of the actual softened state at the actual joint between the two works. . As a conventional example of the friction welding device,
The details are disclosed in Japanese Utility Model Publication No. 3-85183.

[0004]

However, the method of friction-welding a work with the above-mentioned friction-welding device has the following problems. The operation procedure of the friction welding device is set in advance, but it is not something that analyzes the softened state of the work and fully grasps the actual softened state to set the two work pieces more reliably. In order to
In the above-mentioned step, it is generally performed that a large portion (approaching margin) is deformed by applying upset pressure. Therefore, it is necessary to determine the length of the work piece in consideration of this deviation, and since this deviation causes unnecessary burrs around the joint, optimal bonding (preventing unnecessary burrs from occurring) It was not easy to carry out the bonding (suppressing and sufficiently giving the welding strength).

Moreover, as described above, the operation setting of the friction welding device is made independent of the molten state of the contact surface of the work, so that the actual deviation amount tends to vary, and the dimensional accuracy of the product is stable. I didn't. Therefore, it has been required to grasp the softened state of the work in advance and to set the conditions for optimal welding.

The present invention has been made in view of the above problems, and an object thereof is to perform frictional pressure welding with a small margin of deviation so as to suppress the generation of unnecessary burrs at the joint portion and to improve the dimensional accuracy of the product. Is to stabilize and to have sufficient welding strength at the joint.

[0007]

Means for Solving the Problems According to the present invention for solving the above-mentioned problems, one of a pair of workpieces arranged facing each other is rotationally driven and pressed against the other workpiece so that frictional heat is applied to a joint portion of both workpieces. A friction welding method for welding the welded portions of the two workpieces, which are softened by the friction heat, to soften the welded portions in order to maintain the welded portions in a desired softened state and to advance the pressure welding step. It is characterized in that the state is visualized and the rotation speed and feed rate of the work are set based on the visualization.

As a means of the present invention, while rotating one of a pair of works arranged oppositely to each other while press-contacting the other, friction heat is generated at the joint between the two works, and the two works softened by the friction heat. Friction welding method for welding the welded portion of the workpiece, in order to maintain the welded portion in a desired softened state and proceed with the pressure welding step, the frequency fluctuation of vibration caused by the pressure welding of the work is measured, Then, the rotation speed and the feed speed of the work are set.

Further, in order to maintain the joining portion in a desired softened state and proceed with the pressure welding step, a temperature change of friction heat generated in the joining portion due to the pressure welding of the work is measured, and the work is based on the change. It is also possible to set the rotation speed and the feed speed of. Further, as another means in the present invention, in order to maintain the joint portion in a desired softened state to proceed with the pressure contact step, a motor for rotating the work is measured, and a change in load current in the pressure contact step is measured. The rotation speed and the feed speed of the work are set based on the above.

As a further means, one of a pair of opposed works is rotationally driven and pressed against the other to generate frictional heat at the joint between the two works, and the frictional heat joins the two works together. In the friction welding process in which the part is softened and the desired softened state is obtained, and then the upset pressure is applied and the rotation of the work is suddenly stopped, the feeding of the work is stopped for a predetermined time while the softening of the joint is in progress. Is characterized by.

In the present invention, in order to maintain a desired softened state in the friction welding process, the progressing state of softening at the joint between a pair of works is visualized by a high speed camera, and the work feed amount is based on the visualized state. Set the optimum joining zone in relation to the pressing pressure. Then, the rotation speed and the feed speed of the work are set so that the pressure welding step proceeds within the range of the optimum welding zone.

Further, in order to maintain a desired softened state in the friction welding process, the frequency of vibration generated by the pressure welding of a pair of works is measured, and the frequency shows a predetermined frequency fluctuation as the process progresses. Then, the rotation speed and the feed speed of the work are set.

Alternatively, in order to maintain a desired softened state in the friction welding process, a change in the amount of burrs generated at the joint between a pair of works is measured, and based on this, the work feed amount and the generation of burrs are measured. Set the optimum joining zone in relation to the quantity. Then, the rotation speed and the feed speed of the work are set so that the pressure welding step proceeds within the range of the optimum welding zone.

Further, the optimum joining zone can be set on the basis of the temperature change of the frictional heat generated in the joining portion due to the pressure contact of the work, and the temperature change. Further, the optimum joining zone may be set on the basis of the variation of the load current of the motor rotatably driving the work in the pressure welding step.

Further, in the friction welding process, in the step of bringing a pair of works into contact with each other to generate frictional heat at the joint, by stopping the feeding of the work for a predetermined time during the progress of softening of the joint, The softened state of the contact surface is advanced without increasing the work feed.

[0016]

Embodiments of the present invention will be described below based on examples. First, FIGS. 2 and 3 show a friction welding device used in the first embodiment of the present invention. The friction welding device of FIG. 2 has a main spindle body 2 and a clamp 3 on a base 1. The pair of works W ₁ and W ₂ are attached to the spindle body 2 and the clamp 3, respectively.

A main shaft 4 is rotatably supported on the main shaft main body 2. A pulley 5 is attached to the main shaft 4, and the driving force of the motor 6 is transmitted by a belt 27 wound around the pulley 7. A brake 8 is attached to the main shaft 4 so that the rotation of the main shaft 4 can be forcibly stopped. Further, a chuck 9 is attached to the tip of the spindle 4, so that the work W ₁ can be fixed to the spindle 4.

By the way, the main spindle body 2 is attached to the base 1 via the linear guide 10, and the main spindle 4 is attached.
It is possible to move in parallel to the axis of. Further, the main spindle body 2 has an arm 11 protruding into the base 1,
A ball screw 13 driven by a servo motor 12 is inserted into 11 and the main body 2 is driven and guided in the axial direction of the main shaft 4 by the propulsive force generated between the ball screw 13 and the arm 11 by the rotation of the ball screw 13.

The main spindle body 2 has a rotation sensor 16 driven by the main spindle 4 via gears 14 and 15, and monitors the rotation speed of the main spindle 4 (that is, the rotation speed of the work W ₁ ). Further, a stroke sensor is provided between the main spindle body 2 and the base 1.
17 and 17a are provided, and the main spindle body 2 (that is, the work W
The feed rate and feed amount in ₁ ) can be measured. Further, the arm 11 has a load sensor 18 between it and the ball screw 13.
Is provided, and the pressing force applied to the main spindle body 2 (that is, the work W ₁ ) can be measured.

As shown in FIG. 3, the friction welding device has a controller, a motor 6, a servomotor 12, and a rotation sensor.
The stroke sensor 17, the stroke sensor 17, and the load sensor 18 are controlled respectively.

The clamp 3 shown in FIG. 2 is for fixing the work W ₂ to the base 1, and has an X-axis clamp 3a for positioning the work W ₂ in the axial direction of the main shaft 4 and a lateral positioning for the axis. It is composed of a Y-axis clamp 3b that performs the above-mentioned operation and a Z-axis clamp 3c that performs vertical positioning with respect to the axis. 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.

In the friction welding device having the above structure,
While contacting the work W ₂ while rotating the work W ₁ ,
By further increasing the pressure, frictional heat is generated at the joint between the works W ₁ and W ₂ (hereinafter, also simply referred to as a joint), and the frictional heat softens the joint between the two works. Then, allowed to proceed softened to a desired state, by increasing the feed amount of the work W further workpiece W ₁ while stopping the rotation of _one (upset applying pressure), junction integrated dent manner to each other, Welding can be completed.

Further, in this embodiment, a high-speed camera 19 capable of photographing the joint between the works is provided in the vicinity of the contact position between the works W ₁ and W ₂ . Using this high-speed camera 19, the work W for visualizing the softened state at the joint and performing optimum welding based on it
₁ to set the rotational speed N _n and the feed velocity V _n.

Here, the procedure of the friction welding in this embodiment will be described with reference to FIGS. 1, 4, 5, and 6. FIG.
Pressing force between the rotational speed N _n, feed speed V _n and the workpiece W ₁ of the workpiece W ₁ and the workpiece W ₂ of the workpiece W ₁ that varies with the progress of the friction welding process (increase in feed amount S _n of the work W ₁₎ is It is a graphical representation of the relationship of P _n . In particular, a graph showing the relationship between the feed amount of the work W ₁ and the pressing pressure P _n is called R. 4 to 6 are flowcharts of this friction welding process.

As a preparatory step, the works W ₁ and W ₂ are attached to the chuck 9 and the clamp 3, respectively, as shown in FIG. At this time, the works W ₁ and W ₂ are separated. First, as an initial step (see FIG. 4) of the friction welding process, the motor 6 is driven to increase the work W ₁ to a predetermined rotation speed N ₁ obtained by performing test joining in advance (step 1). When the rotation speed of the work W ₁ becomes stable at N ₁ , the controller issues a drive start signal SG ₁ for the servomotor 12. Then, the feed speed of the work W ₁ is increased to a predetermined speed V ₁ (low speed) (step 2). By the way, the servo motor 12 can change its rotation speed stepwise, but in the present embodiment, the feed speed of the work W ₁ is controlled in three steps as described later.

The work W ₁ comes into contact with the work W ₂ at the position of the feed amount S ₀ from the movement start position. The reason why the feed speed of the work W ₁ in the step of bringing the works W ₁ and W ₂ into contact with each other is low is to prevent a large load from being suddenly applied to the motor 6 due to the friction torque generated by the contact. Is.

Next, (see FIG. 5), the load sensor 18 monitors the increase of the pressing pressure between the works W ₁ and W _2, and when the pressure reaches the predetermined pressure P ₁ (step 3), the controller controls the servomotor 12 Issue acceleration signal SG ₂ . The feed speed of the work W ₁ is increased to a predetermined speed V ₂ (medium speed), and accordingly, the pressing pressure is increased to a predetermined pressure P ₂ (step 4). In this step, large frictional heat is generated at the joint between the works W ₁ and W _2, and the softening of the joint between the works is promoted.

Fusion progresses while the joints between the works W ₁ and W ₂ are softened. At this time, the graph R showing the relationship between the feed amount S _n of the work W ₁ and the pressing pressure P _n shows the range of the optimum joining zone Z between the feed amounts S ₁ and S ₂ shown by the shaded portion in the figure. As described in ( ₁₎ , the feed speed V ₂ and the rotation speed N ₁ of the work W ₁ are set. The optimum joining zone Z is set in advance on the basis of the visualization data obtained by photographing the accelerated state of softening of the joining portion by the high speed camera 19. The accelerated state of softening is the emission of light and the change in color due to heat generation at the joint,
Since it can be empirically determined depending on the degree of progress of deformation, it is effective for optimal setting of the above various conditions. Graph R
Is in the range of the optimum joining zone Z, the progress of the softening of the work and the feed rate are well balanced, and finally good welding quality can be obtained.

By the way, when the feed rate is faster than the progress of softening of the work, the joint is too hard for welding. Therefore, the rate of increase of the pressing pressure with respect to the increase of the feed amount increases, and the slope of the graph R becomes steeper, so that it deviates above the optimum joining zone Z (becomes the state of _Ra ). Further, when the feed rate is slower than the progress of softening of the work, the pressing force at the joint is reduced because the work is not softened even though the joint is sufficiently softened. , A so-called pressure release state. Therefore, the pressing pressure decreases even if the feed amount increases, and the graph R deviates below the optimum joining zone Z (R _b
State). Further, the feed rate continues to be insufficient as compared with the progress of softening of the work, and then the feed rate becomes faster than that of the progress of softening of the work, and finally enters the optimum joining zone Z. The case (R _c ) is also conceivable.

In any case, the desired amount of heat generation cannot be obtained and satisfactory dimensional accuracy and welding strength cannot be obtained, so the pressure welding operation is stopped. By the way, when the pressure welding work is stopped in the friction welding process, the work W
_{Since 1} and W ₂ have already been deformed due to the progress of softening of the ends, and may be insufficiently welded depending on the time of discontinuation, reuse is not possible. Therefore, after the pressing work is stopped, the current works W ₁ and W ₂ are removed from the apparatus, a new work is attached, and the pressing work is performed from the beginning.

When the feed amount of the work W ₁ is increased while maintaining the graph R in the optimum joining zone Z, the pressing pressure eventually becomes almost constant at the predetermined value P ₃ (preferably, a good softened state is obtained). In order to maintain it, a phenomenon of continuing to rise slightly occurs (step 5). At this time, if the feed amount of the work W ₁ exceeds S ₂ , the desired product size cannot be obtained, and therefore the pressure welding work is stopped. Workpiece W ₁ feed amount is S
When it is in the range of ₁ to S ₂ , a melt stabilization period (hereinafter referred to as PS period) for maintaining a good softened state is provided until the predetermined feed amount S ₂ is reached (step 6).

During this PS period, the pressing pressure is the predetermined value P ₃
The softened state is maintained so that it becomes constant at. If the PS period is set too long, as in the case where a large work margin is taken as a result, adverse effects such as an increase in the amount of wasteful burrs and a decrease in dimensional accuracy occur, which is not preferable. By the way, in the PS period, the joint reaches the melting point. The melting point means a state in which the conditions for shifting to the final step of the friction welding process (the step of applying the upset pressure to complete the pressure welding) are complete. After this, work W
_When it is confirmed that ₁ has reached the predetermined feed amount S ₂ , the process proceeds to the final step (see FIG. 6) of the friction welding process.

The controller stops the motor 6 and gives the spindle 4 a signal SG ₃ for actuating the brake 8. At the same time, the feed speed of the work W ₁ is changed from V ₂ to V ₃ (high speed).
Then, the signal SG ₄ for raising the signal is output (step 7). During the predetermined time T has elapsed from the occurrence of the signal SG ₃ and SG _4, the feed amount of the work W ₁ reaches the S _3, the pressing pressure between the workpiece W ₁ and W ₂ until a desired upset pressure P ₄ To increase. Further, since the rotation of the work W ₁ is braked, the relative rotation between the works W ₁ and W ₂ is eliminated and heat generation due to friction is eliminated, so that the two works are welded and solidified (step 8). If the feed amount of the work W ₁ does not reach S ₃ , it means that the desired dimensional accuracy was not obtained, and the product is rejected as a defective product. If the rotation speed N does not reach 0, it means that the workpieces W ₁ and W ₂ have failed to be welded, and thus the workpieces are also rejected.

In the above series of pressure welding steps, the accelerated state of softening of the joint is photographed by the high speed camera 19, the optimum joining zone Z is set based on the data, and the graph R is maintained within this range. As a result, a desired welding strength at the joint can be obtained. Further, in order to ensure the dimensional accuracy after welding, the feed amount (S ₂ −S) while the optimum joining zone Z is set by the stroke sensors 17 and 17 a.
₁ ) ≧ (desired feed amount) is monitored, and the servo motor 12 is controlled until the final feed amount S ₃ is reached. Therefore, the dimensional accuracy of the product can be stabilized.

The operation and effect obtained from this embodiment having the above structure are as follows. As described above, by visualizing the softening promotion state of the joint part of the work, it becomes easy to always optimize the operation setting of each part of the friction welding device even when the material and size of the work are changed. . Moreover, since the melting point can be clearly grasped, it is not necessary to take the work margin excessively more than necessary, and a product having a sufficient welding strength with a minimum required feed amount can be obtained. Therefore, it is possible to suppress the generation of unnecessary burrs and facilitate the work of removing burrs in the finishing process. Further, by advancing the pressure welding process while maintaining the optimum joining zone, the feed amount of the work is always an appropriate value, and the final dimensional accuracy can be accurately obtained.

Next, a second embodiment of the present invention will be described with reference to FIGS. In the figure, the same or corresponding parts as those of the first embodiment are designated by the same reference numerals, and detailed description will be omitted.

The difference between the second embodiment and the first embodiment is that the frequency λ of vibration generated by the pressure contact between the works W ₁ and W ₂ is used in order to grasp the progress of the desired softening of the joint in the pressure contact step. The fluctuation of _n is measured, and the rotation speed N _n and the feed speed V _n of the work W ₁ for optimum welding are set based on the measured fluctuation. The friction welding device used in this embodiment is shown in FIG. As shown, clamp 3c
A vibration pickup 20 is attached to the, and a detection signal thereof is amplified by an amplifier 21 and transmitted to a controller (not shown). The installation location of the vibration pickup is not limited to the clamp 3 and may be any location where vibration can be appropriately detected.

Now, the procedure of friction welding in this embodiment will be described with reference to FIGS. 8 and 9. Figure 8 is rotational speed N _n of the work W ₁ that varies with the progress of the friction welding process (increase in feed amount S _n of the work W _1), the feed rate V _n of the work W ₁
3 is a graph showing the relationship between the vibration frequency λ _n detected by the vibration pickup and the vibration frequency λ _n . FIG. 9 is a flowchart of this friction welding process, and the initial step (FIG. 4) and the final step (FIG. 6) of the friction welding process in the first embodiment are also applied to this embodiment.

As shown in FIG. 8, first, the motor 6 is driven to raise the work W ₁ to a predetermined rotation speed N ₁ (s
tep1). Then, the vibration pickup 20 provided in the clamp 3c detects the vibration of the frequency λ ₁ generated by the operation of the motor 6. The rotation speed of the work W ₁ is N
_When stable at ₁ , the controller outputs a drive start signal SG ₁ for the servomotor 12. Then, the feed speed of the work W ₁ is increased to a predetermined speed V ₁ (step 2: the above, FIG.
See the flowchart in FIG. The work W ₁ comes into contact with the work W ₂ at the position of the feed amount S ₀ from the movement start position,
Violent vibration of frequency λ ₄ is generated from the junction. While maintaining this state, the feed amount of the work W ₁ is increased to S ₁ . When the feed amount reaches S ₁ (step 3), the controller outputs the acceleration signal SG ₂ of the servo motor 12,
Increase the feed rate to V ₂ . If the feed amount of the work W ₁ is increased as it is, a large frictional heat is generated at the joint, and the softening of the joint of the work is promoted.

[0040] As progress of softening of the workpiece is optimal, setting the rotational speed N ₁ and feed speed V ₁ of the workpiece W _1, the vibration generated at the junction, the range of frequency lambda ₂ without lambda ₃ Can be converged. Even if the work W ₁ is further fed thereafter, the generated vibration is λ ₂ to λ ₂ .
Stable in the ₃ frequency bands. In such a state, it is assumed that the softened state of the joint has reached the melting point. In this embodiment, the frequency band of λ _{2 to} λ ₃ is the optimum junction zone. When the feed amount of the work W ₁ reaches the predetermined feed amount S ₂ (step 4), if the generated frequency is converged in the frequency band of λ ₂ to λ ₃ , the point of convergence of the frequency. Set a predetermined PS period from (step
5). By the way, the feed amount of the work W ₁ is the predetermined feed amount S
When the generated frequency does not converge to the frequency band of λ ₂ to λ ₃ when it reaches ₂ , it is in the state that the desired amount of heat generation cannot be obtained, and the dimensional accuracy and welding strength are not improved. The pressure welding work was stopped because satisfactory results could not be obtained.

In the PS period in the present embodiment, the rotation speed N ₁ and the feed speed V ₂ of the work W ₁ are set so that the generated frequency is stable in the frequency band of λ ₂ to λ ₃ , and the joint portion The softened state of is maintained at the melting point. After the lapse of the PS period, the process proceeds to the final step of the friction welding process shown in FIG. 6 as in the first embodiment, and the controller outputs the output signal S
G ₃ and SG ₄ are output (shift to step 7).

The operation and effect obtained from this embodiment having the above-mentioned structure are as follows. As described above, since the acceleration state of the softening of the joint is recognized from the frequency of the vibration generated at the joint of the two workpieces, and the rotation speed and the feed speed of the workpiece are set based on the recognized state, the material of the workpieces is set. It is easy to always optimize the operation setting of each part of the friction welding device even when the size and the size are changed. Other functions and effects are the same as those in the first embodiment, and the description thereof is omitted here.

Next, a third embodiment of the present invention will be described with reference to FIGS. In the figure, the same or corresponding parts as those of the first and second embodiments are designated by the same reference numerals and detailed description thereof will be omitted. By the way, the difference between the third embodiment and the first and second embodiments is that the workpieces W ₁ and W ₂ are welded to each other in the welding portion in order to grasp the progress of the desired softening of the welding portion in the welding step. Rotational speed N _n of the work W ₁ for measuring the change in the amount of burrs and performing optimal welding based on the change
And the feeding speed V _n is set.

A friction welding device used in this embodiment is shown in FIGS. 10 and 11. As shown, a displacement sensor 22 is arranged at the contact position between the works W ₁ and W ₂ . The displacement sensor 22 is
The displacement amount of the object to be measured is detected by irradiating the laser band 23 from the light projecting unit 22a to the light receiving unit 22b, and the object to be measured interrupts the laser band 23 to reduce the amount of light received by the light receiving unit 22b. To do. The displacement sensor 22 is supported by a bracket 221 at an appropriate portion arranged on the base 1,
The laser band 23 is arranged so as to be irradiated at a predetermined distance X from the outer wall of the work. The predetermined distance X has a value capable of detecting a change in the amount of burrs described later.

Here, the state of growth of burrs that increase at the joint between the works W ₁ and W ₂ with the progress of the friction welding process will be described with reference to FIGS. 12 (a) to 12 (d). To do. FIG. 12A shows the start point of friction welding between the works W ₁ and W ₂ . FIG. 12B shows an initial step of burr generation. The amount of feed of the work W ₁ increases, and the burr 24 becomes the work W due to the softening of the joint due to frictional heat.
_It is generated in the diametrical direction of the work from the joint of ₁ and W ₂ .
FIG. 12 (c) is the middle step of burr generation. The feed amount of the work W ₁ further increases, and accordingly, the amount of burr 24 generated also increases, and the leading ends start to be wound so as to be separated from each other. FIG. 12D shows the latter step of the burr generation. The feed amount of W ₁ is further increased, and the tip of the growing burr 24 is integrated again with the outer wall of the work. This Figure 12
The burr 24 shown in (d) is an ideal shape that occurs when the pressure welding process is advanced so as to give a desired welding strength at the joint.

As the burr 24 grows as described above, the area where the laser band 23 is blocked by the burr 24 increases, and the progress of softening at the joint can be grasped. By the way, in FIGS. 12 (a) to 12 (d), the light projecting section is located below.
The light receiving unit is provided above, and the laser band 23 is radiated upward. In the state shown in FIG. 12 (b), since the width of the burr and the diameter of the tip portion are small, only a part (the central portion in the width direction) of the laser band 23 irradiated in parallel with the work is blocked. However, Figure 12
When the state of (c) is reached, the width of the burr and the diameter of the tip portion are enlarged, and the laser band 23 is blocked from the central portion with a certain width. Further, in the state of FIG. 12 (d), the width of the burr and the diameter of the tip portion are further expanded, and the width at which the burr blocks the laser band 23 becomes the maximum until then. When the amount of burrs 24 generated (that is, the area where the laser band 23 is blocked by the burrs 24) exceeds a predetermined value, it can be determined that the softened state of the joint has reached the melting point.

Now, the procedure of friction welding in this embodiment will be described with reference to FIGS. 13 to 15. Figure 13 is rotational speed N _n of the work W ₁ that varies with the progress of the friction welding process (increase in feed amount S _n of the work W _1), the workpiece W ₁ feed speed V _n and the workpiece W ₁ and the workpiece W ₂ FIG. 6 is a graph showing the relationship of the blocked area D _n of the laser band 23 which is proportional to the amount of burrs generated by pressure welding. In particular, R is a graph showing the relationship between the feed amount S _n of the work W ₁ and the area D _n.
Call it _B. 14 and 15 are flowcharts of this friction welding process, and the initial step (FIG. 4) of the friction welding process in the first embodiment is also applied to this embodiment.

First, similarly to the initial step of the work process of the first embodiment shown in FIG. 4, the rotation speed of the work W ₁ is increased to N ₁ (step 1) and the feed speed of the work W ₁ is increased to V _1. Allow (step 2). The work W ₁ comes into contact with the work W ₂ at the position of the feed amount S ₀ from the movement start position.
Due to the occurrence of burrs at the joint between the works W ₁ and W ₂ ,
When the blocked area of the laser band 23 reaches D ₁ or the feed amount of the work W ₁ reaches S ₁ , (step
3), the controller is the acceleration signal SG _{2 of the} servo motor 12
Put out. The feed speed of the work W ₁ is increased to a predetermined speed V ₂ (step 4), and the rate of increase of burrs is increased accordingly.

By the way, a graph R _B showing the relationship between the feed amount S _n and the area D _n of the workpiece W ₁ is, the workpiece W ₁ to be in the range of optimum bonding zone Z _B indicated by a hatched portion in FIG feed The speed V ₂ and the rotation speed N ₁ are set. The optimum joining zone Z _B is preliminarily set based on the results of several preliminary joinings. When the graph R _B is in the range of this optimum joining zone Z _B , the progress state of the softening of the work and the feed rate are balanced, and finally good welding quality can be obtained.

By the way, when the graph R _B deviates above the optimum joining zone Z _B , it shows that the burr grows faster than the feed amount of the work W ₁ , and the burr is generated more than necessary. I will let you. Therefore, it is necessary to set the feed speed V ₂ or the rotation speed N ₁ of the work W ₁ to a lower value. Further, the graph R _B shows this optimum joining zone Z.
If it deviates below _B , the growth of burrs is slower than the feed amount of the work W ₁ , and the desired welding strength at the joint cannot be obtained. Therefore, it is necessary to set the feed speed V ₂ or the rotation speed N ₁ of the work W ₁ to a higher value. In any case, if the graph R _B deviates from the range of the optimum joining zone Z _B , a satisfactory product cannot be obtained, and therefore the pressure welding work is stopped.

When the feed amount of the work W ₁ is increased while maintaining the graph R _B in the optimum joining zone Z _B , the area blocked by the burr eventually reaches the range of D _{S1 to} D _S2 (step 5 ). When reaching the range of D _{S1 to} D _S2 , the softened state of the joint indicates that the melting point has been reached. Then, the controller starts a predetermined P from the time when the area becomes D _S1.
Set the S period (step 6). In the PS period in this embodiment, the area blocked by the burr is the optimum joining zone Z.
It is controlled to be in the range of _B , and the softened state of the joint is maintained at the melting point. After the lapse of the PS period (when the feed amount reaches S ₂ ), the controller outputs output signals SG ₃ and SG ₄ (step 7).

While the predetermined time T has passed from the generation of the signals SG ₃ and SG ₄ , the feed amount of the work W ₁ reaches S ₃ , and the area blocked by the burr reaches D _{4 to} D ₅ . ,
Pressure contact is completed (step 8). Further, since the rotation of the work W ₁ is braked, the relative rotation between the works W ₁ and W ₂ is eliminated and heat generation due to friction is eliminated, so that the two works are welded and solidified. At this time, if the area blocked by burr does not fall within D _{4 to} D ₅ , it is determined to be a defective product.

The operation and effect obtained from this embodiment having the above-mentioned structure are as follows. As described above, the amount of burrs generated at the joint between two workpieces is detected, and the rotation speed and feed rate of the workpieces are set based on this, so even if the material or dimensions of the workpieces are changed, It is always easy to optimize the operating settings for each part of the friction welding device. Other functions and effects are the same as those of the first and second embodiments, and the description thereof is omitted here. By the way, in the present embodiment, in order to detect the amount of burrs generated, the displacement sensor 22 is used, but by imaging the growth of burrs with a video camera or the like and performing image processing, each part of the friction welding device is It is also possible to use it for the operation setting of.

Next, a fourth embodiment of the present invention will be described with reference to FIGS. In the figure, the same or corresponding parts as those of the first to third embodiments are designated by the same reference numerals, and detailed description thereof will be omitted. The difference between the fourth embodiment and the first to third embodiments is that in order to grasp the progress of the desired softening of the joint in the pressure welding process, the friction heat generated in the joint by the pressure welding of the works W ₁ and W ₂ is performed. Is detected, and the rotation speed N _n and the feed speed V _n of the work W ₁ for optimum joining are set based on the temperature change.

FIG. 16 shows the friction welding device used in this embodiment. As shown in the drawing, in the vicinity of the contact positions of the works W ₁ and W ₂ ,
A temperature sensor 25 is arranged. The temperature sensor 25 is
It is attached to the main spindle body 2 via 251. Further, the measurement point of the temperature sensor 25, so that the end face of the workpiece W _1, to fix the workpiece W ₁ to the chuck 9. Here, a method for matching the measurement point of the temperature sensor 25 and the end surface of the work W ₁ will be described below. First, the work W ₂ is fixed to the clamp 3. Further, the work W ₁ is temporarily fixed to the chuck 9. Then, the spindle body is moved in the direction of the work W ₂ ,
The work W ₁ and the work W ₂ are brought into contact with each other. Since the work W ₁ is in the temporarily fixed state, the work W ₁ is brought into close contact with the innermost portion of the chuck 9 by the contact pressure between the work W ₁ and the work W _2, and is positioned at a predetermined position. Here, the chuck 9 is strongly closed to completely fix the work W ₁ .

Here, the procedure of the friction welding in this embodiment will be described with reference to FIGS. 17 and 18. Figure 17 is rotational speed N _n of the work W ₁ that varies with the progress of the friction welding process (increase in feed amount S _n of the work W _1), the feed rate V _n of the work W _1
3 is a graph showing the relationship between the temperature t _n of the joint portion caused by the pressure contact between the work W ₁ and the work W ₂ . In particular, a graph showing the relationship between the feed amount of the work W ₁ and the temperature of the joint is referred to as R _t . FIG. 18 is a flowchart of this friction welding process, and the initial step (FIG. 4) and the final step (FIG. 6) of the friction welding process in the first embodiment are also applied to this embodiment.

First, similarly to the initial step of the work process of the first embodiment shown in FIG. 4, the rotation speed of the work W ₁ is increased to N ₁ (step 1), and the feed speed of the work W ₁ is increased to V _1. Allow (step 2). The work W ₁ comes into contact with the work W ₂ at the position of the feed amount S ₀ from the movement start position. Friction heat is generated at the joint between the works W ₁ and W _2, and the temperature t _n at the joint gradually rises. When the feed amount of the work W ₁ reaches S ₁ (step 3), the controller outputs the acceleration signal SG ₂ of the servo motor 12 to increase the feed speed to V ₂ . If the feed amount of the work W ₁ is increased as it is, a large frictional heat is generated in the joint portion, and the joint portion of the workpiece is softened.

Fusion proceeds while the joints between the works W ₁ and W ₂ are softened. At this time, the graph R _t showing the relationship between the feed amount of the work W ₁ and the temperature of the joint is in the range of the optimum joint zone Z _t indicated by the hatched portion in the drawing so that the work W is
Setting the _first and the feeding speed V ₂ and the rotational speed N _1. The optimum joining zone Z _t is preliminarily set based on the result of performing preliminary joining several times. When the graph R _t is in the range of the optimum joining zone Z _t , the progress state of the softening of the work and the feed rate are balanced, and finally good welding quality can be obtained.

When the graph R _t deviates from the optimum joining zone Z _t, it means that the amount of heat generated at the joint is in an inappropriate state, and the softening of the joint is not progressing well. Therefore, since the dimensional accuracy and the welding strength of the product cannot be obtained, the pressure welding work is stopped.

While maintaining the graph R _t in the optimum joining zone Z _t , the feed amount of the work W ₁ is increased to S ₂ .
When it is confirmed that the temperature of the joint is within the range of t ₁ to t _{2 when} the feed amount reaches S ₂ (step 4), the controller sets a predetermined PS period (step 4).
5). In the PS period in this embodiment, the softened state of the joint is controlled to be the temperature t ₃ or higher at which it reaches the melting point.
When the temperature of the joint is equal to or higher than the melting point t ₃ at the time when the PS period elapses (feed amount S ₂ ': step 6), the final step of the friction welding process shown in FIG. 6 is performed as in the first embodiment. (Step
7 or later). Further, when the temperature of the joint is less than t ₃ at the time when the PS period elapses, it is in a state in which the desired amount of heat generation cannot be obtained, and satisfactory dimensional accuracy and welding strength are obtained. Since there is not, the pressure welding work is stopped.

The operational effects obtained from the fourth embodiment having the above-mentioned structure are as follows. As described above, since the accelerated state of softening of the joint is recognized from the temperature change of the friction heat generated in the joint of the two works, and the rotation speed and the feed rate of the work are set based on the recognized state, Even when the material and size of the friction welding device are changed, it is easy to always optimize the operation setting of each part of the friction welding device. Other functions and effects are the same as those in the first embodiment, and the description thereof is omitted here.

Next, a fifth embodiment of the present invention will be described with reference to FIGS. In the figure, the same or corresponding parts as those of the first to fourth embodiments are designated by the same reference numerals, and detailed description thereof will be omitted.

The difference between the fifth embodiment and the first to fourth embodiments is that the workpieces W ₁ and W ₂ are pressed to the joints in order to grasp the progress of the desired softening of the joints in the pressing step. The rotation speed N _n and the feed speed V _n of the work W ₁ for optimum welding are set by utilizing the fact that the load current of the motor 6 fluctuates due to the frictional resistance generated. The friction welding device used in this example is shown in FIG. A load current detector 26 is connected to the motor 6 that drives the main shaft 4 as shown in the figure, and the detection signal thereof is transmitted to a controller (not shown).

Here, the procedure of friction welding in this embodiment will be described with reference to FIGS. 20 and 21. Figure 20 is rotational speed N _n of the work W ₁ that varies with the progress of the friction welding process (increase in feed amount S _n of the work W _1), the feed rate V _n of the work W _1
3 is a graph showing the relationship between the load current value I _n of the motor 6 which varies depending on the frictional resistance generated by the pressure contact between the work W ₁ and the work W ₂ . In particular, a graph showing the relationship between the feed amount S _n of the work W ₁ and the load current value I _n of the motor 6 is referred to as R _i . FIG. 21 is a flow chart of this friction welding process. The initial step (FIG. 4) and the final step (FIG. 6) of the friction welding process in the first embodiment are
This is also applied in this embodiment.

First, similarly to the initial step of the work process of the first embodiment shown in FIG. 4, the rotation speed of the work W ₁ is increased to N ₁ (step 1), and the feed speed of the work W ₁ is increased to V _1. Allow (step 2). By the way, in the process of starting the motor 6 to raise the work W ₁ to a predetermined rotation speed N ₁ , the load current I _n once rises as shown by R _i a and then decreases to a predetermined value. Stabilize. The work W ₁ comes into contact with the work W ₂ and the frictional resistance at the joint increases, so that the motor 6 is loaded. Therefore, in order to maintain the rotational speed N ₁ of the work W _1, the load current of the motor 6 increases people Ordinal. The joint portion generates heat due to frictional resistance and progresses softening.

When the feed amount of the work W ₁ is increased to S ₁ as it is (step 3), the load current exceeds the predetermined value I ₃ , and the feed amount S _n of the work W ₁ and the load current value I of the motor 6 are set. _{When the} graph R _i showing the relationship with _n is in the range of the preset optimum joining zone Z _i , the progress state of the softening of the work and the feed rate are well balanced, and finally good quality welding is achieved. You can get quality.
Therefore, the feed amount of the work W ₁ is continuously increased.

When the softening of the contact surface is insufficient as compared with the feed amount of the work W ₁ , the friction resistance increases and the load current of the motor 6 increases, and the graph R _i shows the optimum joining zone Z. Deflection above _i . Therefore, it is necessary to set the feed speed V ₁ or the rotation speed N ₁ of the work W ₁ to a lower value. Further, when the softening of the contact surface progresses rapidly as compared with the feed amount of the work W ₁ , the friction resistance decreases and the load current of the motor 6 decreases, and the graph R _b shows the optimum joining zone Z _i. Deviate below. Therefore, it is necessary to set the feed speed V ₁ or the rotation speed N ₁ of the work W ₁ to a higher value. In any case, if the graph R _i deviates from the range of this optimum joining zone Z _i , a satisfactory product cannot be obtained, and therefore the pressure welding work is stopped.

The softening of the joint further progresses and reaches the melting point. At this time, since the frictional resistance of the contact surface becomes small, the value of the load current decreases and maintains a constant value. Then, when the feed amount of the work W ₁ reaches S ₂ (step 4) and the load current is within the range of I ₁ to I ₂ , the controller sets a predetermined PS period (step 5). In the PS period in this embodiment, the load current is controlled so as to maintain I _{1 to} I _2, and the softened state of the joint is maintained at the melting point.
After the lapse of PS period (when the feed amount reaches S ₂ ': step
In 6), the final step of the friction welding process shown in FIG. 6 is executed as in the first embodiment. In this embodiment, the load current of the motor 6 once exceeds I ₃ and then drops again to catch a stable state, whereby it can be understood that the contact surface has reached the melting point.

The operation and effect obtained from the fifth embodiment having the above structure is as follows. As described above, by detecting the change in the frictional resistance generated at the joint between the two works by detecting the change in the load current of the motor 6, the accelerated state of softening of the joint is recognized, and based on this, Since the rotation speed and the feed speed of the work are set, it is easy to always optimize the operation setting of each part of the friction welding device even when the material and dimensions of the work are changed. Other functions and effects are the same as those in the first embodiment, and the description thereof is omitted here.

Next, a sixth embodiment of the present invention will be described with reference to FIGS. In the figure, the same or corresponding parts as those of the first to fifth embodiments are designated by the same reference numerals, and detailed description thereof will be omitted.

The sixth embodiment relates to a method of operating a friction welding device for optimal welding of works. Fig. 22
Is the rotational speed N _n of the work W _{1 which} changes with the progress of the friction welding process (elapsed time T _n from the start of the friction welding work),
Feed rate of the workpiece W ₁ V _n and the workpiece W ₁ and the workpiece W
₂ is a graph showing the relationship between ₂ and the pressing pressure P _n . In particular, a graph showing the relationship between the elapsed time T _n and the pressing pressure P _n is called R _P. Further, the feed amount S _n of the work W _{1 at} the elapsed time T _n is also displayed. 23 and 24 are flowcharts of this friction welding process, and the initial step (FIG. 4) of the friction welding process in the first embodiment is also applied to this embodiment.

First, similarly to the initial step of the work process of the first embodiment shown in FIG. 4, the rotation speed of the work W ₁ is increased to N ₁ (step 1), and the feed speed of the work W ₁ is increased to V _1. Allow (step 2). The work W ₁ comes into contact with the work W ₂ at the position of the feed amount S ₀ from the movement start position. Then, the pressing pressure at the joint between the work W ₁ and the work W ₂ increases. The feed amount of the work W ₁ is the predetermined value S
The pressing force at the time when it reaches ₁ (step 3) is a predetermined value P
When it is ₂ or more, sufficient frictional heat is generated due to the frictional resistance of the joint portion, and the joint portion of the work begins to soften. Then, the pressing force of the joint portion decreases as the joint portion deforms due to softening. At the time when the feed amount of the work W ₁ reaches the predetermined value S ₁ , when the pressing pressure is below P ₂ , the frictional heat generation of the contact surface becomes insufficient and the subsequent softening of the joint is not promoted. It is not possible to obtain a product with satisfactory accuracy and welding strength. Therefore, the pressure welding work is stopped.

When the feed amount of the work W ₁ reaches S _t (step 4), the controller outputs the stop signal SG ₂ 'of the servomotor 12 to set the feed speed of the work W ₁ to 0 (step 4).
5). When the rotation of the work W ₁ is continued in this state, the pressing pressure gradually decreases, but since the frictional heat generation continues, the softened state of the contact surface is maintained. After stopping the workpiece W ₁ sends a predetermined time t ₀ (step6), the pressing force is detected that to no P ₁ is in the range of P ₁ ', the contact surface that it has reached the melting point become. Here, a melt stabilization period (hereinafter referred to as PS period) for maintaining a good softened state is provided for a predetermined time (step 7). This PS period, to the pressing pressure is not P ₁ to maintain P ₁ '. After the PS period has elapsed, the process proceeds to the final step (see FIG. 24) of the friction welding process.

The controller stops the motor 6 and issues a signal SG ₃ to the main shaft 4 to activate the brake 8. At the same time, a signal SG ₄ 'for increasing the feed speed of the work W ₁ to V ₂ is issued (step 8). Signals SG ₃ and SG ₄ '
During the predetermined time t ₁ has elapsed from the occurrence of the, workpiece W ₁
The feed amount reaches the S _3, the pressing pressure between the workpiece W ₁ and W ₂ is increased until the desired upset pressure P ₃ to P _4. Further, since the rotation of the work W ₁ is braked, the relative rotation between the works W ₁ and W ₂ is eliminated and heat generation due to friction is eliminated, so that the two works are welded and solidified (st
ep9). When the pressing force of the workpiece W ₁ does not reach the P ₃ to P ₄ indicates that sufficient welding strength can not be obtained, it will be repelled as a defective product. If the rotation speed N does not reach 0, it means that the workpieces W ₁ and W ₂ have failed to be welded, and thus the workpieces are also rejected.

By the way, in the present embodiment, when the rotational speed N _n and the feed speed V _n of the work W ₁ are set, the methods shown in the first to fifth embodiments can be used.

The operational effects obtained from the sixth embodiment having the above construction are as follows. While the softening of the joint is in progress, the workpiece feed is stopped for a predetermined time, and the softening state of the contact surface is advanced in that state to reach the melting point of the contact surface. It is possible to reduce the work margin required in the step. Therefore, the occurrence of burrs when the press contact is finally completed can be suppressed to the necessary minimum, and the waste of the work can be reduced.

[0077]

Advantageous Effects According to the present invention, the following effects can be obtained with respect to the conventional friction welding method. Visualize the progress of softening at the joint of the work with a high-speed camera, based on that, set the optimum joining zone in the relationship between the work feed amount and the pressing pressure, and within the range of the optimum joining zone Since the rotation speed and the feed speed of the work are set so that the process proceeds, it is easy to always optimize the operation setting of each part of the friction welding device even when the material and dimensions of the work are changed. . Moreover, since the melting point can be clearly grasped and the process can proceed, it is not necessary to take the work margin excessively more than necessary, which saves the material and sufficient welding with the minimum necessary feed amount. It can be a product with strength. Therefore, it is possible to suppress the generation of unnecessary burrs and facilitate the work of removing burrs in the finishing process. Further, by advancing the pressure welding process while maintaining the optimum joining zone, the feed amount of the work is always an appropriate value, and the final dimensional accuracy can be accurately obtained.

Further, the frequency of the vibration generated by the pressure contact of the pair of works is measured to set the optimum joining zone in the relation between the feed amount of the works and the frequency fluctuation, and the frequency is set to a predetermined value in accordance with the progress of the process. The same effect can be obtained by setting the rotation speed and the feed speed of the work so as to show the frequency fluctuation.

Furthermore, the change in the amount of burrs generated at the joint between a pair of works is measured, and based on this, the optimum joining zone in the relationship between the work feed amount and the amount of burrs is set, and the optimum The same effect can be obtained by setting the rotation speed and the feed speed of the work so that the pressure welding process proceeds within the range of the joining zone.

Alternatively, the optimum joining zone can be set on the basis of the temperature change of the frictional heat generated in the joining portion due to the pressure contact of the work, and based on this. Also,
The optimum joining zone is a motor for rotationally driving the workpiece, and measures a change in load current in the pressure welding step,
It is also possible to set based on it, and in any case, by setting the rotation speed and the feed speed of the work so that the pressure welding step proceeds within the range of the optimum welding zone, The effect of can be obtained.

Further, in the friction welding process, in the step of bringing the pair of works into contact with each other to generate frictional heat at the joint, by stopping the feeding of the work for a predetermined time during the softening of the joint, Since the softened state of the contact surface is advanced without increasing the feed of the work, it is possible to reduce the work margin required in the step until the contact surface reaches the melting point. Therefore, the occurrence of burrs when the press contact is finally completed can be suppressed to the necessary minimum, and the waste of the work can be reduced.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship of various parameters that change with the progress of the friction welding process in the first embodiment of the present invention.

FIG. 2 is a schematic view showing a friction welding device in the first embodiment of the present invention.

FIG. 3 is a schematic view showing a friction welding device in a first embodiment of the present invention.

FIG. 4 is a flow chart showing initial steps of the friction welding process shown in FIG. 1.

5 is a flow chart diagram showing an intermediate step of the friction welding process shown in FIG. 1. FIG.

6 is a flowchart showing the final step of the friction welding process shown in FIG.

FIG. 7 is a schematic diagram showing a friction welding device according to a second embodiment of the present invention.

FIG. 8 is a graph showing the relationship of various parameters that change with the progress of the friction welding process in the second embodiment of the present invention.

9 is a flowchart showing an intermediate step of the friction welding process shown in FIG.

FIG. 10 is a schematic diagram showing a friction welding device according to a third embodiment of the present invention.

FIG. 11 is a schematic diagram taken in the direction of arrow A in FIG.

12 (a) to 12 (d) are schematic diagrams showing how burrs grow as the friction welding process proceeds.

FIG. 13 is a graph showing the relationship of various parameters that change with the progress of the friction welding process in the third embodiment of the present invention.

14 is a flowchart showing an intermediate step of the friction welding process shown in FIG. 13.

15 is a flowchart showing the final step of the friction welding process shown in FIG. 13.

FIG. 16 is a schematic diagram showing a friction welding device according to a fourth embodiment of the present invention.

FIG. 17 is a graph showing the relationship of various parameters that change with the progress of the friction welding process in the fourth example of the present invention.

18 is a flowchart showing an intermediate step of the friction welding process shown in FIG.

FIG. 19 is a schematic view showing a friction welding device in a fifth embodiment of the present invention.

FIG. 20 is a graph showing the relationship of various parameters that change with the progress of the friction welding process in the fifth example of the present invention.

FIG. 21 is a flowchart showing an intermediate step of the friction welding process shown in FIG. 20.

FIG. 22 is a graph showing the relationship of various parameters that change with the progress of the friction welding process in the sixth example of the present invention.

23 is a flowchart showing an intermediate step of the friction welding process shown in FIG. 22.

24 is a flowchart showing the final step of the friction welding process shown in FIG. 22.

[Explanation of symbols]

N _n Work rotation speed P _n Work pressing pressure R Graph showing the relationship between work feed amount and press pressure S _n Work feed amount V _n Work feed speed Z Optimal welding zone

Claims (6)

[Claims] 1. One of a pair of workpieces arranged opposite to each other is rotationally driven and pressed against the other to generate frictional heat at a joint portion of both workpieces, and the joint portion of the two workpieces softened by the frictional heat is welded. A friction welding method, in which the softened state of the welded portion is visualized in order to maintain the welded portion in a desired softened state and to proceed with the pressure welding step, and based on that, the rotation speed and the feed rate of the workpiece. A friction welding method characterized by setting. 2. One of a pair of opposed works is rotationally driven while being pressed against the other to generate friction heat at the joint between the two works, and the joint between the works softened by the friction heat is welded. A friction welding method, wherein the frequency of vibration generated by the pressure welding of the work is measured in order to proceed the pressure welding process while maintaining the joint in a desired softened state, and the rotation of the work is based on it. A friction welding method characterized by setting a speed and a feed rate. 3. One of a pair of works arranged opposite to each other is rotationally driven while being pressed against the other to generate frictional heat at the joint between the two works, and weld the joints between the two works softened by the frictional heat. A friction welding method, in order to maintain the joining portion in a desired softened state and proceed with the welding step, a change in the amount of burrs generated in the joining portion due to the welding of the work is measured, and based on that, The friction welding method is characterized in that the rotation speed and the feed speed of the work are set. 4. One of a pair of workpieces arranged opposite to each other is rotationally driven while being pressed against the other to generate friction heat at the joint between the two workpieces, and the joint between the workpieces softened by the friction heat is welded. A friction welding method, in which the temperature change of the friction heat generated in the welding portion by the pressure welding of the work is measured in order to proceed the pressure welding step while maintaining the welding portion in a desired softened state. A friction welding method, wherein the rotation speed and the feed speed of the work are set. 5. A pair of opposed works is rotationally driven while being pressed against the other to generate frictional heat at the joint between the two works, and weld the joints between the two works softened by the frictional heat. A friction welding method, in order to advance the welding process while maintaining the joint in a desired softened state, a motor for rotationally driving the work, measuring a change in load current in the welding process, and measuring it. A friction welding method, wherein the rotation speed and the feed speed of the work are set based on the above. 6. A frictional heat is generated at a joint between both workpieces by rotating one of the pair of workpieces facing each other while rotationally driving the workpieces, and the frictional heat softens the joints between the workpieces. In the friction welding step of applying an upset pressure and suddenly stopping the rotation of the work after obtaining a desired softened state, during the softening of the joint,
A friction welding method characterized by stopping the feeding of a work for a predetermined time.