JPS6350181B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention abuts the joint parts of plastic joint members against each other, rubs them against each other, melts the joint part, and then stops the frictional movement and cools the melted part. The present invention relates to a method and apparatus for determining the quality of joined products by so-called friction welding, which solidifies and joins joined members.

(Prior art) A welding method in which the joined parts of plastic joining members are butted against each other, rubbed against each other, the joined parts are melted, and then the frictional movement is stopped and the fused parts are cooled and solidified to join the joined parts. Traditionally known as welding.

(Problems to be Solved by the Invention) Friction welding has high joining performance and excellent productivity, so it is widely used for joining plastics. However, since the joining performance of friction welded products cannot be confirmed by destructive testing, there is a problem in that complete quality assurance cannot be achieved.

It would be particularly desirable if a pass/fail judgment method or a pass/fail judgment device capable of determining the quality of a joined product during welding work could be realized, since it would be possible to significantly improve the reliability of welding without the need for inspection.

(Means for Solving the Problems) The present invention responds to such demands and provides a method and apparatus that can reliably determine the quality of a joined product during welding work.

In other words, in a welding method in which the joined parts of joined members are brought together and rubbed against each other, the joined parts are melted, the frictional movement is stopped, and the molten part is cooled and solidified to join the joined members. A method for determining the quality of jointed products by friction welding, in which the frictional force on the joint surfaces of the joints is measured, and when this measured value is smaller than a preset value, the jointed product is considered good, and when it is larger, it is rejected. In a device that butts and frictions each other and joins, for example, a means for measuring the frictional force during frictional movement by providing a detection device operated by an actuating body of a fixed side gripper rotatably attached to a pressurizing jig. The measured value is compared with a preset reference value, and if the friction force after the start of braking is lower than the reference value, it is displayed as a non-defective product, or the bonded product is classified as a non-defective product. This is a device for determining the quality of welded joints.

(Effects of the Invention) According to the present invention, it is possible to determine whether the joint is good or bad during the joining process, which greatly improves product quality, eliminates the need for inspection man-hours, and significantly reduces joining costs. It has characteristics.

(Example) The embodiments shown in the drawings will be described below.

FIG. 1 is a basic configuration diagram of a conventionally known friction welding device.

In FIG. 1, 7a and 7b are joining members,
Each is held by jigs 6a and 6b. The gripper 6a on the drive side is fixed to the main shaft 4, and is rotated by the motor 1 via the brake 3 and clutch 2 in the direction of the arrow 5.

On the other hand, the gripper 6b on the fixed side does not rotate, but is pressurized by the cylinder 8 in the direction of the arrow 9.

In such a welding device, the joining members 7a, 7b
Clutch 2 is rotated relative to each other for a predetermined period of time while pressurizing them to melt the joint surfaces.
After activating and cutting off the power, the brake 3 applies braking to stop the frictional motion, perform cooling, and complete welding.

FIG. 2 is a basic configuration diagram of another conventionally known type of friction welding device.

In FIG. 2, 17a and 17b are joining members, and 16a and 16b are jigs for gripping the joining members. The jig 16b on the pressurizing side is the cylinder 18
This allows pressure to be applied in the direction of arrow 19.

The jig 16a on the moving side is connected to the eccentric portion 14A of the rotating shaft 14 via the bearing 10,
Further, rotation is restrained by a restraint device 20.

The rotating shaft 14 is connected to a motor 11 via a brake 13 and a clutch 12, and can be rotated by the motor 11 as shown by an arrow 15.

FIG. 3 shows the jig 16a and rotating shaft 1 of the device shown in FIG.
The engagement relationship with 4 is shown in detail.

When the rotating shaft 14 is rotated in such a combination, it performs a circular orbital motion with a radius equal to the distance r between the center O ₀ of the rotating shaft 14 and the center O ₁ of the rotating shaft 14A, like the jig 16a.

That is, the joining members 17a and 17b perform a frictional motion relative to each other in a circular orbit.

In addition, in the device shown in FIG. 2, if the hole 21 of the jig 16a circumscribing the bearing 10 is made into an elongated hole as shown in FIG. This is a reciprocating motion that strokes.

When the center O ₀ of the rotating shaft 14 and the center O ₀ of the rotating shaft 14' are aligned, the radius of the orbit rapidly converges, the frictional motion stops, and welding is completed (Patent Application No. 52-54606)
issue).

As described above, there are several types of friction welding devices depending on the type of frictional motion, but all of them have the drawback that it is not possible to determine the quality of the welded products during the welding process.

The present invention provides a method and apparatus that can determine whether the welding is good or bad in the welding process in friction welding using various forms of motion.

There is no reliable method for friction welding production control other than destructive inspection.

Conventionally, therefore, defects have been prevented by using a welding device with high accuracy in setting conditions and by selecting welding conditions with sufficient margin.

Conventionally known welding conditions such as friction speed, friction pressure, and friction time should be able to be managed with this management method, but in reality, even if welded under well-scrutinized welding conditions, defective products may still occur. The problem is that it can be done.

As a result of intensive investigation into this point, we discovered that the friction force after the frictional motion starts braking has a significant relationship with the bonding performance.

Figures 5 and 6 show two typical examples of stress generated during frictional motion in the friction welding process.

That is, when the rotational speed reaches a predetermined value and the resin begins to melt, the frictional force increases and eventually stabilizes at a certain level (FIGS. 5 and 6B).

When braking is applied from this state (point .

Note that during welding, the joint surface is in a solid phase, a molten phase, or somewhere in between, so the stress generated by the movement of friction welding is not necessarily only frictional force, but the present invention Now, we have decided to collectively refer to this stress simply as frictional force.

When observing the friction force during the friction welding process in many examples, it can be roughly divided into the types shown in FIGS. 5 and 6.

That is, as shown in FIG. 5, the frictional force decreases smoothly after the start of motion braking, and as shown in FIG. 6, the frictional force rapidly increases after the start of braking.

Furthermore, it has been discovered that the bonding efficiency in the case shown in FIG. 6 is inferior to the case shown in FIG. 5 without exception.

Therefore, by measuring the frictional force after the start of braking during the welding process, it is possible to know whether the welding was successful.

Specifically, the frictional force F _o before the start of braking in the welding process (see Figures 5 and 6 B) was measured in advance through a preliminary experiment, and a stress F _{s slightly larger than this was used as a reference, and the friction force F o} was measured after the start of braking. If the frictional force of the bonded product is measured and the bonded product is accepted if it is not greater than F _s , it is possible to determine the quality of the bonded product during the welding process without going through an inspection.

Note that it is not necessary to measure the frictional force only after the start of braking; the same result can be obtained by measuring the entire process, measuring only the maximum frictional force, and comparing this with a reference value.

Figure 5 shows that even if the frictional force does not show a peak during braking, the frictional force F _o at steady state B
As shown in FIG. 7, there is a negative relationship between the bonding strength and the bonding strength.

Therefore, if the required performance of the joined product is strict, it is necessary not only to eliminate the case where a peak appears after the start of braking during the friction process as shown in Fig. 6B, but also to further lower the reference value to improve the steady state B. It is better to manage the frictional force itself to be low.

The second aspect of the invention relates to a suitable device used in the above-described method for determining the quality of a joined product during a welding process.

That is, a friction force measuring device is installed in the friction welding apparatus shown in Figs. 1 and 2 to measure the friction force, and the measured value is compared with a preset standard to indicate the quality of the welded product. It is a device having means for performing.

FIG. 8 is an example of the friction welding device of the invention,
The part of the gripping tool is shown. In FIGS. 8A and 8B, the stationary gripping tool 26A is rotatably attached to the pressing jig 25 via bearings 23 and 24.

Further, 26' is a protrusion forming an operating body of a detection device provided on the gripper 26A, and 27 is a sensor pedestal fixed to the welding device base, to which the load cell 22 is attached.

A compressive stress as indicated by an arrow 29 is applied to the load cell 22 due to a frictional force whose direction is indicated by an arrow 28 .

Therefore, by taking out the strain signal of this load cell, the frictional force can be measured. The method of measuring the frictional force is not limited to this example, and includes a method of measuring the torsional stress of the rotating shaft 4 or 14, a method of measuring the stress of the jig 6 or 16,
Alternatively, there is a method in which a strain gauge is inserted between the jig 6 or 16 and the bonded object 7 or 17.

If such a device is installed in normal welding equipment,
Frictional force during welding can be measured. These measured values can be displayed throughout the entire process using a graphic recorder or oscilloscope, and the data can also be processed to determine the maximum value.

Furthermore, the measured value is compared with a preset reference value, and if the measured value is larger, it is displayed as "defective" or the bonded product is assigned to be defective.

Of course, if the measured value is below the standard value, it is considered a "good product".
It goes without saying that the information may be displayed as , or may be classified, or both may be displayed.

Alternatively, the measured values may be data-processed to obtain the maximum frictional force, and this may be compared with a reference value.

FIG. 9 is an example of an apparatus that directly compares the maximum frictional force with a reference value without using data processing.

In FIG. 9, reference numeral 26A is a fixed-side gripping tool that is rotatably mounted in the same manner as in FIG. 8. 26' is a protrusion of this gripping tool. 30 is
This is a sensor base fixed to the welding equipment base. 31 is a spring, and the sensor base 30
and the protrusion 26' of the gripper.

32 is a switch provided on the sensor base 30, and when the projection 26' of the gripper moves in the direction of arrow 33, the electrical circuit is turned on.
Or, it can be set as “no”.

When joining is performed using such a device, the gripping tool 26 moves in the direction of the arrow 32 due to frictional force, and the switch 3
Activate 2.

Therefore, if the switch 32 is used to make the indicator light blink, and the spring is appropriately selected, the indicator light can be made to blink when the frictional force exceeds a predetermined stress.

If the spring 31 is selected in advance so that the switch 32 is activated by the protrusion 26' of the gripper when a standard stress is applied to the spring 31, the quality of the connection can be determined by the blinking of the indicator light. be able to.

Next, an example of an automatic sorting device will be described.

In the joining apparatus shown in FIG. 10, a hole 51 is provided in the base 50 below the gripper 6. A two-way chute 52 having a switching damper 53 is provided in the hole 51.

The damper 53 rotates around the shaft 54 and takes a position 53A indicated by a solid line and a position 53B indicated by a dotted line. When the damper 53 is not in operation, the spring 5
7, the tank takes the position 53A indicated by the solid line, so the tank A side of the chute is open.

A spring 5 is connected to the shaft 54 via an electromagnetic clutch 55.
It is connected to a constant torque motor 56 whose rotational direction is opposite to the operating direction of 7.

The electromagnetic clutch 55 is connected to the switch 32 of FIG. 9 through a circuit as shown in FIG. 12th
DC in the figure is a direct current power supply.

In such a device, when the friction force exceeds a predetermined value and the switch 32 is activated, the relay is activated, the electromagnetic clutch 55 indicated by K is activated, and the damper 53 is rotated by the motor 55 against the spring 57. It now takes the position 53B indicated by the dotted line.

Therefore, the tank B side of the chute 52 is opened only for the time preset by the timer.
Therefore, the joined products that have been removed from the gripper after joining fall into the hole 51, pass through the chute 52B, and are sorted into tank B, which is a stock of defective products.

If the product is normal, the switch 32 will not close, so the tank A side of the chute 52 will be open, and the product will be sorted into the tank A of good products.

The above is an example of an automatic sorting device, and it goes without saying that any other automatic sorting device can be employed.

As detailed above, if the present invention is implemented,
Since the quality of the joint can be judged during the joining process, the quality of the product is greatly improved and the inspection process is no longer necessary.
It has the characteristic of being able to significantly reduce joining costs.

[Brief explanation of the drawing]

FIG. 1 shows an example of a conventionally known friction welding device. FIG. 2 shows another example of a conventionally known friction welding device. FIG. 3 shows a detailed view of the engagement portion between the rotating shaft and the welding jig of the friction welding device shown in FIG. 2.
FIG. 4 is an explanatory diagram of yet another friction welding device, and is a sectional view corresponding to the plane XX' in FIG. 3. FIGS. 5 and 6 each show examples of changes in frictional force over time during the joining process. FIG. 7 is a graph showing the relationship between frictional force and bonding strength in a steady portion during the bonding process. FIGS. 8A and 8B show an example of the friction welding device of the present invention, and are a cut front view and a cross-sectional view showing the vicinity of the gripping tool. FIG. 9 shows another example of the friction welding device of the present invention, and shows the maximum friction detection portion. FIG. 10 and FIG. 11 are a sectional view and a perspective view of the automatic sorting device. FIG. 12 shows an example of the electric circuit of the automatic sorting device. 25... Pressure jig, 26A... Fixed side gripping tool, 2
6'...Protrusion, 22...Load cell, 27...Sensor pedestal, 30...Sensor base, 31...Spring, 32
...Switch.

Claims (1)

[Claims] 1. In a welding method in which the joined parts of joined members are butted against each other, rubbed against each other, the joined parts are melted, the frictional motion is stopped, and the fused parts are cooled and solidified to join the joined members. A method for determining the quality of joined products by friction welding, in which the frictional force on the joined surfaces after the start of braking of motion is measured, and when this measured value is smaller than a preset value, the joined product is judged as good, and when it is larger, it is judged as defective. 2. In a device that butts the joint parts of joining members and causes them to rub against each other, there is a means for measuring the friction force after the start of braking, and a means to compare the measured value with a preset reference value, and to compare the measured value with a preset reference value, and to reduce the friction from the reference value throughout the entire friction process. A device for determining the quality of a joined product by friction welding, which has means for displaying a non-defective product or classifying a joined product into a non-defective product when the force is lower. 3. Friction welding according to claim 2, in which the frictional force after the frictional motion starts to be braked is measured by a detection device operated by the operating body of the stationary gripping tool rotatably attached to the pressing jig. A device for determining the quality of bonded products.