JP3433584B2 - Friction welding method - Google Patents

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 work by using frictional heat, and more particularly to a method for facilitating control 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, softening progresses 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.

The friction welding device for performing this friction welding is arranged so that one of a pair of works is clamped and the other is fixed to a chuck provided on the rotation driving means, and is coaxially arranged. Then, while rotating one work, it can be moved in parallel so as to abut against the other work. 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. In addition, maintaining the desired joint in a desired softened state
Joining by pressing the work in order to advance the process
The change in the amount of burrs generated in the
Setting the rotation speed and feed speed of the workpiece
May be

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.

In the present invention, in order to maintain the desired softening state in the friction welding process, the progressing state of softening at the joining portion of a pair of works is visualized by a high speed camera, and the work feed amount is based on the visualization. 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 may be set on the basis of the temperature change of frictional heat generated in the joining portion due to the pressure contact of the work, and based on this. Further, the optimum joining zone may be set on the basis of the fluctuation of the load current of the motor that rotationally drives the work in the press contacting step, and based on the measurement.

[0014]

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 W1 and W2 are attached to the main spindle body 2 and the clamp 3, respectively.

A main shaft 4 is rotatably supported by the main shaft 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 W1 can be fixed to the spindle 4.

By the way, the main spindle body 2 is attached to the base 1 via a 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 to monitor the rotation speed of the main spindle 4 (that is, the rotation speed of the work W1). Further, a stroke sensor is provided between the main spindle body 2 and the base 1.
17 and 17a are provided, and the spindle main body 2 (that is, the work W1
It is possible to measure the feed rate and the feed amount of). 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 W1) can be measured.

As shown in FIG. 3, the friction welding device has a controller, a motor 6, a servo motor 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 W2 to the base 1, and is for positioning the work W2 in the axial direction of the spindle 4 and the X-axis clamp 3a for positioning the work W2 in the left-right direction. It is composed of a Y-axis clamp 3b and a Z-axis clamp 3c for vertically positioning with respect to the axis. Then, the work W2 can be arranged coaxially with the work W1 fixed to the main shaft 4 by appropriately adjusting each shaft clamp.

In the friction welding device having the above structure,
The work W1 is rotated and brought into contact with the work W2,
By further increasing the pressure, frictional heat is generated at the joint between the works W1 and W2 (hereinafter, also simply referred to as a joint), and the frictional heat softens the joint between the two works. Then, by advancing the softening to a desired state, and further increasing the feed amount of the work W1 (applying the upset pressure) while stopping the rotation of the work W1, the joints are intruded into each other to be integrated and welded. Can be completed.

Further, in the present embodiment, a high speed camera 19 capable of photographing the joint between the works W1 and W2 is provided in the vicinity of the contact position between the works W1 and W2. Using this high-speed camera 19, the work W for visualizing the softened state at the joint and performing optimum welding based on it
The rotation speed Nn and the feed speed Vn of 1 are set.

Now, the procedure of friction welding in this embodiment will be described with reference to FIGS. 1, 4, 5 and 6. Figure 1
Is a graph showing the relationship between the rotational speed Nn of the work W1, the feed speed Vn of the work W1, and the pressing pressure Pn of the work W1 and the work W2, which change with the progress of the friction welding process (increase of the feed amount Sn of the work W1). Is. In particular, a graph showing the relationship between the feed amount of the work W1 and the pressing pressure Pn is called R. 4 to 6 are flowcharts of this friction welding process.

As a preparatory step, the works W1 and W2 are attached to the chuck 9 and the clamp 3, respectively, as shown in FIG. At this time, the works W1 and W2 are separated from each other. First, as an initial step (see FIG. 4) of the friction welding process, the motor 6 is driven to increase the work W1 to a predetermined rotation speed N1 obtained by performing test joining in advance (step 1). When the rotation speed of the work W1 becomes stable at N1, the controller issues a drive start signal SG1 for the servomotor 12. Then, the feed speed of the work W1 is increased to a predetermined speed V1 (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 W1 is controlled in three steps as described later.

The work W1 comes into contact with the work W2 at the feed amount S0 from the movement start position. The reason why the feed speed of the work W1 in the step of bringing the works W1 and W2 into contact with each other is set low is to prevent the motor 6 from being suddenly subjected to a large load due to the friction torque generated by the contact.

Next, (see FIG. 5), the load sensor 18 monitors the increase in the pressing pressure between the workpieces W1 and W2, and when the pressure reaches the predetermined pressure P1 (step 3), the controller outputs the acceleration signal SG2 of the servo motor 12. Give out. The feed speed of the work W1 increases to a predetermined speed V2 (medium speed), and the pressing pressure accordingly increases to a predetermined pressure P2 (step 4). In this step, large frictional heat is generated at the joint between the works W1 and W2, and the softening of the joint between the works is promoted.

Fusion progresses while the joints between the works W1 and W2 are softened. At this time, the graph R showing the relationship between the feed amount Sn of the work W1 and the pressing force Pn is between the feed amounts S1 and S2 in the range of the optimum joining zone Z shown by the hatched portion in the figure, The feed speed V2 and the rotation speed N1 of the work W1 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 higher 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 (in 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 (Rb
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 (Rc) is also conceivable.

In any case, the desired calorific value 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 W1
, W2 has already been deformed due to the progress of softening of the ends, and it may be insufficiently welded at some points when it is stopped, so that it cannot be reused. Therefore, after the pressing work is stopped, the current works W1 and W2 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 W1 is increased while maintaining the graph R in the optimum joining zone Z, the pressing pressure eventually becomes almost constant at the predetermined value P3 (preferably, a good softened state is maintained). Therefore, a phenomenon occurs that continues to rise slightly (step 5). At this time, if the feed amount of the work W1 exceeds S2, the desired product size cannot be obtained, and therefore the pressure welding work is stopped. Workpiece W1 feed amount is S
When it is in the range of 1 to S2, a melt stabilization period (hereinafter referred to as PS period) for maintaining a good softened state is provided until the predetermined feed amount S2 is reached (step 6).

During this PS period, the pressing pressure is the predetermined value P3.
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 S2, 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 SG3 for actuating the brake 8. At the same time, the feed speed of the work W1 is changed from V2 to V3 (high speed).
Then, a signal SG4 for raising the voltage is output (step 7). The feed amount of the work W1 reaches S3 while the predetermined time T has elapsed from the generation of the signals SG3 and SG4, and the pressing pressure between the works W1 and W2 increases to the desired upset pressure P4. Further, since the rotation of the work W1 is braked, the relative rotation between the works W1 and W2 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 W1 does not reach S3, 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 W1 and W2 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 secure the dimensional accuracy after welding, the feed amount (S2-S) during the setting of the optimum joining zone Z by the stroke sensors 17 and 17a.
1) ≧ (desired feed amount) is monitored, and the servomotor 12 is controlled until the final feed amount S3 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 thereof will be omitted.

The difference between the second embodiment and the first embodiment is that in order to grasp the progress of the desired softening of the joint in the pressure welding step, the fluctuation of the frequency λn of the vibration caused by the pressure welding of the works W1 and W2. Is measured, and the rotation speed Nn and the feed speed Vn of the work W1 for optimum welding are set based on the measurement. 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. FIG. 8 shows the rotation speed Nn of the work W1 and the feed speed Vn of the work W1 which change with the progress of the friction welding process (increase in the feed amount Sn of the work W1).
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 W1 to a predetermined rotation speed N1 (s
tep1). Then, the vibration pickup 20 provided in the clamp 3c detects the vibration of the frequency λ1 generated by the operation of the motor 6. The rotation speed of the work W1 is N
When stable at 1, the controller issues a drive start signal SG1 for the servomotor 12. Then, the feed speed of the work W1 is increased to the predetermined speed V1 (step 2: the above, FIG.
Refer to the flow chart). The work W1 comes into contact with the work W2 at the position of the feed amount S0 from the movement start position,
Violent vibration of frequency λ4 is generated from the junction. While maintaining this state, the feed amount of the work W1 is increased to S1. When the feed amount reaches S1 (step 3), the controller outputs the acceleration signal SG2 of the servomotor 12,
Increase the feed rate to V2. If the feed amount of the work W1 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.

When the rotation speed N1 and the feed speed V1 of the work W1 are set so that the progress of the softening of the work is optimum, the vibration generated at the joint can be converged in the range of frequencies λ2 to λ3. . After that, even if the work W1 is further advanced, the generated vibration is λ2 to λ.
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 λ2 to λ3 is set as the optimum junction zone. When the feed amount of the work W1 reaches the predetermined feed amount S2 (step 4), if the generated frequency is converged in the frequency band of λ2 to λ3, the predetermined PS is reached from the point of convergence of the frequency. Set the period (step
5). By the way, the feed amount of the work W1 is the predetermined feed amount S
If the generated frequency does not converge to the frequency band of λ2 to λ3 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 satisfied. Since nothing can be obtained, the pressure welding work is stopped.

In the PS period in this embodiment, the rotation speed N1 and the feed speed V2 of the work W1 are set so that the generated frequency is stable in the frequency band of λ2 to λ3, and the softened state of the joint is melted. Keep to the 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
G3 and SG4 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 third embodiment is different from the first and second embodiments in that in order to grasp the progress state of the desired softening of the joint in the pressure welding step, the burrs generated in the joint by the pressure welding of the works W1 and W2. Rotation speed Nn of the work W1 for measuring the change in the generated amount and performing optimum welding based on the change
And the feed rate Vn is set.

A friction welding device used in this embodiment is shown in FIGS. 10 and 11. As shown in the figure, the displacement sensor 22 is arranged at the contact position between the works W1 and W2. 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.

Now, how the burrs grow and increase at the joint between the works W1 and W2 with the progress of the friction welding process will be described with reference to FIGS. 12 (a) to 12 (d). FIG. 12 (a) shows the starting point of friction welding between the works W1 and W2. FIG. 12B shows an initial step of burr generation. The feed amount of the work W1 is increased, and the joining portion is softened by frictional heat, so that the burr 24 becomes the work W.
It is generated in the diametrical direction of the work from the junction of 1 and W2.
FIG. 12 (c) is the middle step of burr generation. The feed amount of the work W1 further increases, and accordingly, the amount of burrs 24 generated also increases, and the tips start to be separated from each other. FIG. 12D shows the latter step of the burr generation. The feed amount of W1 further increases, 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.

Here, the procedure of the friction welding in this embodiment will be described with reference to FIGS. 13 to 15. FIG. 13 shows the rotation speed Nn of the work W1, the feed speed Vn of the work W1, and the amount of burr generated by the pressure contact between the work W1 and the work W2, which change with the progress of the friction welding process (increase in the feed amount Sn of the work W1). 6 is a graph showing the proportional relationship between the blocked area Dn of the laser band 23. In particular, R is a graph showing the relationship between the feed amount Sn of the work W1 and the area Dn.
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 W1 is increased to N1 (step 1), and the feed speed of the work W1 is increased to V1 (step 2). . The work W1 comes into contact with the work W2 at the feed amount S0 from the movement start position.
Due to the occurrence of burrs at the joint between the workpieces W1 and W2,
When the blocked area of the laser band 23 reaches D1 or the feed amount of the work W1 reaches S1, (step
3), the controller is the acceleration signal SG2 of the servo motor 12.
Give out. The feed speed of the work W1 is increased to a predetermined speed V2 (step 4), and the rate of increase of burrs is increased accordingly.

By the way, the graph RB showing the relationship between the feed amount Sn and the area Dn of the work W1 is in the range of the optimum joining zone ZB indicated by the shaded portion in the figure, so that the feed speed V2 and the rotation speed N1 of the work W1 are shown. And. The optimum joining zone ZB is preliminarily set based on the results of several preliminary joinings. When the graph RB is in the range of the optimum joining zone ZB, 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 RB deviates above the optimum joining zone ZB, it shows that the growth of burrs is faster than the feed amount of the work W1, and burrs are generated more than necessary. . Therefore, it is necessary to set the feed speed V2 or the rotation speed N1 of the work W1 to a lower value. Also, the graph RB shows this optimum joining zone Z.
When it deviates below B, the growth of burrs is slower than the feed amount of the work W1, and it becomes impossible to obtain the desired welding strength at the joint. Therefore, it is necessary to set the feed speed V2 or the rotation speed N1 of the work W1 to a higher value. In any case, if the graph RB deviates from the range of this optimum joining zone ZB, a satisfactory product cannot be obtained, and therefore the welding operation is stopped.

When the feed amount of the work W1 is increased while maintaining the graph RB in the optimum joining zone ZB, the area blocked by the burr eventually reaches the range DS1 to DS2 (step 5). When this range of DS1 to DS2 is reached, it means that the softened state of the joint has reached the melting point. Then, the controller starts a predetermined P from the time when the area becomes DS1.
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 S2), the controller outputs output signals SG3 and SG4 (step 7).

While the predetermined time T has passed from the generation of the signals SG3 and SG4, the feed amount of the work W1 reaches S3, the area blocked by the burr reaches D4 to D5,
Pressure contact is completed (step 8). Further, since the rotation of the work W1 is braked, the relative rotation between the works W1 and W2 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 D4 to D5, it is determined as 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 fourth embodiment is different from the first to third embodiments in that the friction heat generated in the welded portion by the pressure welding of the works W1 and W2 is detected in order to grasp the progress of the desired softening of the welded portion in the pressure welding process. However, the rotation speed Nn and the feed speed Vn of the work W1 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 figure, in the vicinity of the contact positions of the works W1 and W2,
A temperature sensor 25 is arranged. The temperature sensor 25 is
It is attached to the main spindle body 2 via 251. Further, the work W1 is fixed to the chuck 9 so that the measurement point of the temperature sensor 25 is the end surface of the work W1. Here, a method of matching the measurement point of the temperature sensor 25 and the end surface of the work W1 will be described below. First, the work W2 is fixed to the clamp 3. Further, the work W1 is temporarily fixed to the chuck 9. Then, the spindle body is moved in the direction of the work W2,
The work W1 and the work W2 are brought into contact with each other. Since the work W1 is in the temporarily fixed state, the work W1 is brought into close contact with the innermost portion of the chuck 9 by the contact pressure between the work W1 and the work W2 and positioned at a predetermined position. At this point, the chuck 9 is strongly closed to completely fix the work W1.

Here, the procedure of the friction welding in this embodiment will be described with reference to FIGS. 17 and 18. FIG. 17 shows the rotation speed Nn of the work W1 and the feed speed Vn of the work W1 which change with the progress of the friction welding process (increase in the feed amount Sn of the work W1).
3 is a graph showing the relationship between the temperature tn of the joint portion caused by the pressure contact between the work W1 and the work W2. In particular, a graph showing the relationship between the feed amount of the work W1 and the temperature of the joint is referred to as Rt. 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 W1 is increased to N1 (step 1), and the feed speed of the work W1 is increased to V1 (step 2). . The work W1 comes into contact with the work W2 at the feed amount S0 from the movement start position. Friction heat is generated at the joint between the works W1 and W2, and the temperature tn at the joint gradually rises. When the feed amount of the work W1 reaches S1 (step 3), the controller outputs the acceleration signal SG2 of the servo motor 12 to increase the feed speed to V2. If the feed amount of the work W1 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 progresses while the joints between the works W1 and W2 are softened. At this time, the graph Rt showing the relationship between the feed amount of the work W1 and the temperature of the joint is in the range of the optimum joint zone Zt indicated by the shaded portion in the drawing so that the work W is
The feed speed V2 and the rotation speed N1 of 1 are set. The optimum joining zone Zt is preliminarily set based on the results of several preliminary joinings. When the graph Rt is in the range of the optimum joining zone Zt, the progress state of the softening of the work and the feed rate are balanced, and finally good welding quality can be obtained.

If the graph Rt deviates from the optimum joining zone Zt, 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.

The feed amount of the work W1 is increased to S2 while maintaining the graph Rt in the optimum joining zone Zt.
When it is confirmed that the temperature of the joint is within the range of t1 to t2 when the feed amount reaches S2 (step 4), the controller sets a predetermined PS period (step).
5). In the PS period in this embodiment, control is performed so that the softened state of the joint becomes the temperature t3 or higher at which it reaches the melting point.
When the temperature of the joint is equal to or higher than the melting point t3 at the time when the PS period elapses (feed amount S2 ': step6), as in the first embodiment, the final step (step) of the friction welding process shown in FIG.
7 or later). Further, when the temperature of the joint portion is less than t3 after the lapse of the PS period, the desired amount of heat generation cannot be obtained, and the dimensional accuracy and the welding strength are not satisfactory. Therefore, the pressure welding work is stopped.

The operation and effect obtained from the fourth embodiment having the above structure is 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 in order to grasp the progress of the desired softening of the joint in the pressure welding step, the friction generated in the joint by the pressure welding of the works W1 and W2. By utilizing the fact that the load current of the motor 6 fluctuates due to the resistance, the rotation speed Nn and the feed speed Vn of the work W1 for optimum welding are set. 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. FIG. 20 shows the rotation speed Nn of the work W1 and the feed speed Vn of the work W1 which change with the progress of the friction welding process (increase in the feed amount Sn of the work W1).
3 is a graph showing the relationship between the load current value In of the motor 6 which varies depending on the frictional resistance generated by the pressure contact between the work W1 and the work W2. In particular, a graph showing the relationship between the feed amount Sn of the work W1 and the load current value In of the motor 6 is called Ri. 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
It 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 W1 is increased to N1 (step 1), and the feed speed of the work W1 is increased to V1 (step 2). . By the way, in the process of starting the motor 6 and raising the work W1 to a predetermined rotation speed N1, the load current In rises once as indicated by Ri a and then decreases and stabilizes at a predetermined value. The work W1 comes into contact with the work W2, and the frictional resistance at the joint increases, so that the motor 6 is loaded. Therefore, the load current of the motor 6 gradually increases in order to maintain the rotation speed N1 of the work W1. The joint portion generates heat due to frictional resistance and progresses softening.

When the feed amount of the work W1 is increased to S1 as it is (step 3), the load current exceeds the predetermined value I3, and the relation between the feed amount Sn of the work W1 and the load current value In of the motor 6 is shown. When the graph Ri is within the range of the preset optimum joining zone Zi, the progress of the softening of the work and the feed rate are well balanced, and finally good welding quality can be obtained.
Therefore, the feed amount of the work W1 is continuously increased.

When the softening of the contact surface is insufficient as compared with the feed amount of the work W1, the friction resistance increases and the load current of the motor 6 increases, and the graph Ri indicates the upper part of the optimum joining zone Zi. Deviate to. Therefore, it is necessary to set the feed speed V1 or the rotation speed N1 of the work W1 to a lower value. Further, when the softening of the contact surface progresses rapidly as compared with the feed amount of the work W1, the frictional resistance decreases and the load current of the motor 6 decreases, and the graph Rb shows below the optimum joining zone Zi. Deviate. Therefore, it is necessary to set the feed speed V1 or the rotation speed N1 of the work W1 to a higher value. In any case, if the graph Ri is outside the range of this optimum joining zone Zi, a satisfactory product cannot be obtained, so that the welding operation 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 W1 reaches S2 (step 4) and the load current is within the range of I1 to I2, the controller sets a predetermined PS period (step 5). During the PS period in this embodiment, the load current is controlled so as to maintain I1 to I2, and the softened state of the joint is maintained at the melting point.
After the lapse of PS period (when the feed amount reaches S2 ': step
In 6), the final step of the friction welding process shown in FIG. 6 is executed as in the first embodiment. In the present embodiment, the load current of the motor 6 once exceeds I3 and then decreases again to catch a stable state, whereby it can be understood that the contact surface has reached the melting point.

The operational effects obtained from the fifth embodiment having the above-mentioned structure are 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. Figure 22
Is the rotational speed Nn of the work W1 which changes with the progress of the friction welding process (elapsed time Tn from the start of the friction welding work),
Feed rate Vn of work W1 and work W1 and work W
2 is a graph showing the relationship between 2 and the pressing pressure Pn. In particular, a graph showing the relationship between the elapsed time Tn and the pressing pressure Pn is called RP. Further, the feed amount Sn of the work W1 at the elapsed time Tn 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 W1 is increased to N1 (step 1), and the feed speed of the work W1 is increased to V1 (step 2). . The work W1 comes into contact with the work W2 at the feed amount S0 from the movement start position. Then, the pressing pressure at the joint between the work W1 and the work W2 increases. Workpiece W1 feed amount is a predetermined value S
The pressing force at the time when 1 is reached (step 3) is the predetermined value P
When it is 2 or more, sufficient frictional heat is generated due to the frictional resistance of the joint, and softening of the joint of the work begins. Then, the pressing force of the joint portion decreases as the joint portion deforms due to softening. When the feed amount of the work W1 reaches the predetermined value S1 and the pressing pressure is lower than P2, 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 strength. Therefore, the pressure welding work is stopped.

When the feed amount of the work W1 reaches St (step 4), the controller outputs the stop signal SG2 'of the servomotor 12 to set the feed speed of the work W1 to 0 (step 4).
5). When the work W1 continues to rotate in this state, the pressing pressure gradually decreases, but friction heat generation continues, so that the softened state of the contact surface is maintained. After the feeding of the work W1 is stopped for a predetermined time t0 (step 6), when it is detected that the pressing pressure is in the range of P1 to P1 ', the contact surface has reached the melting point. 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). In this PS period, the pressing pressure maintains P1 to P1 '. 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 SG3 to the main shaft 4 to activate the brake 8. At the same time, a signal SG4 'for increasing the feed rate of the work W1 to V2 is issued (step 8). Signals SG3 and SG4 '
During a predetermined time t1 from the occurrence of
Reaches a value S3, and the pressing pressure between the works W1 and W2 increases to the desired upset pressure P3 to P4. Further, since the rotation of the work W1 is braked, the relative rotation between the works W1 and W2 is eliminated and heat generation due to friction is eliminated, so that the two works are welded and solidified (st
ep9). When the pressing pressure of the work W1 does not reach P3 to P4, it indicates that sufficient welding strength 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 W1 and W2 have failed to be welded, and thus the workpieces are also rejected.

By the way, in the present embodiment, when the rotational speed Nn and the feed speed Vn of the work W1 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 structure 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.

[0075]

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, saving 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 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.

Further, the change in the amount of burrs generated at the joint between the 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 at the joint due to the pressure contact of the work pieces, 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.

[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 view 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.

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

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

FIG. 16 is a schematic view 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.

FIG. 18 is a flowchart showing an intermediate step of the friction welding process shown in FIG. 17.

FIG. 19 is a schematic view showing a friction welding device according to 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.

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

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

[Explanation of symbols]

Nn Work rotation speed Pn Work pressing pressure R Graph showing the relationship between work feed amount and press pressure Sn Work feed amount Vn Work feed speed Z Optimal welding zone

Claims (5)

(57) [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 order to proceed the pressure welding step while maintaining the joint portion in a desired softened state,
A friction welding method, wherein the softened state of the joint is visualized and the rotation speed and the feed speed of the work are set based on the visualized state. 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, in order to proceed the pressure welding step while maintaining the joint portion in a desired softened state,
A friction welding method characterized in that the frequency variation of vibration caused by the pressure welding of the work is measured, and the rotation speed and the feed speed of the work are set based on the measurement. 3. 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 order to proceed the pressure welding step while maintaining the joint portion in a desired softened state,
A friction welding method, characterized in that a change in the amount of burrs generated at a joint due to the pressure welding of the work is measured, and the rotation speed and the feed speed of the work are set based on the change. 4. One of a pair of opposed workpieces 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 order to proceed the pressure welding step while maintaining the joint portion in a desired softened state,
A friction welding method, wherein a temperature change of frictional heat generated at a joint due to the pressure welding of the work is measured, and the rotation speed and the feed speed of the work are set based on the change. 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 the joints between the two works softened by the frictional heat are welded together. A friction welding method, in order to proceed the pressure welding step while maintaining the joint portion in a desired softened state,
A friction welding method, which comprises: measuring a variation of a load current of a motor that rotationally drives the workpiece in the pressing step, and setting a rotation speed and a feed speed of the workpiece based on the measurement.