JPH0213619B2 - - Google Patents

Abstract

PURPOSE:To obtain jointed products having good appearance and good bonding property withouth the need for removing flash by providing a rack on the side wall of one connecting part and also a given form of a flash-housing projection corresponding to the rack and near the joint portion of the other connecting part. CONSTITUTION:When plastic connecting parts 1 and 2 with a round joint portion 3 are contacted with each other and welded frictionally at the joint portion 3, a projection 7 of a height of bmm. is provided over all peripheral side in such a way as to have a side face 7a such that the width t of the aperture 8 between the side face 7a and a side wall 1a near the joint portion 3 of the connecting part 1. And, a rack 9 is at a place (a+b)mm. away from the joint portion and corresponding to the projection 7 in the connecting part 2. As the joining process comes to completion, the projection 7 comes into contact with the rack 9 and thereby the pressing force is received even by the width W' of the projection in addition to the width W of the joint portion. So that, pressure to be imposed on the joint portion 3 is abruptly reduced, the melting speed is decreased, and a dispersion in the height of the jointed product is lessened.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to rotary friction welding of plastics, and is a joining method that does not generate external burrs that occur during welding and can provide high joining efficiency. Therefore, a bonded product with excellent appearance and good bonding performance can be obtained without going through a finishing process to remove burrs.

As shown in FIG.
are brought into contact with each other, facing each other, fixing one joining member 2 and fixing the other joining member 1 in the contact surface direction (arrow P).
This is a joining method in which the joints 3 are rotated while being pressurized to generate heat and melt due to friction, and then the movement is stopped and the joints are cooled and solidified. This joining method has high joining performance, low joining cost, and high productivity.
Attention has been paid. However, there is a problem in that during bonding, burrs 4 are generated due to melting of the bonded portion 3, as shown in FIG. Therefore, after joining, it was necessary to remove burrs from the joint. In addition, there were cases in which it was impossible to remove internal burrs, and the method could not be applied depending on the application.

Therefore, as shown in FIG. 2, a protrusion 5 for storing burrs is provided near the joint part 3 of one joint member 1.
The generated burr 4 is stored in a gap 6 between the protrusion 5 and the joining member 2 so that the generated burr is not visible from the outside. Since the burr 4 is generally quite bulky and the direction in which it is generated is not constant, it is necessary to make the gap 6 quite large. Therefore, the protrusion 5 for storing burrs
may even become too large to be used due to design constraints on the joints.

The present invention focuses on this point, and by storing burrs in a rational manner, the joint part becomes compact and the degree of freedom in design increases. This provides a bonding method that can be improved.

The present invention will be explained below with reference to drawings showing embodiments.

As shown in FIGS. 3 and 4, the first aspect of the present invention is to provide a shelf 9 on the side wall of one joint member 1 at a predetermined distance away from the joint 3, and This is a plastic friction welding method in which a predetermined burr storage protrusion 7 is provided near the shelf 9 in correspondence with the shelf 9. In other words, the protrusion 7 for storing burrs
is the gap t between the inner surface 7a of the protrusion 7 and the corresponding side surface 1a near the joint portion 3 of the other joint member 1.
is within a predetermined range to suppress the outflow of burrs, and the shelf portion 9 is appropriately set in relation to the height b of the protrusion 7 for storing burrs to easily and reliably prevent burrs from starting. It consists of making it possible to bond.

The projection 7 for storing burrs is provided in the vicinity of the joint portion 3 in the direction of the corresponding joint member 1 so as to be substantially parallel to the rotation axis. Further, the width t of the gap 8 for storing burrs formed by the inner surface 7a of the protrusion 7 for storing burrs and the side surface 1a near the joint portion 3 of the corresponding joining member 1 is set to 0.1 to 0.5 mm, and the width W of the joint portion is set to 0.1 to 0.5 mm. 0.2W times or less. However, as shown in FIG. 3, the width W of the joint is the difference between the outer radius r ₁ and the inner radius r ₂ of the joint surface 3. This also applies to the case where the joining surface is a conical surface or a combination thereof, as in the examples shown in FIGS. 7 and 8.

When the width t of the gap 8 is within the above range, not only the generation of burrs is suppressed, but also the generated burrs do not become bulky and spread. This is the width of gap 8 t
This is thought to be because the formed burr is difficult to flow out because the gap is narrow. The optimal clearance varies depending on the melt viscosity of the resin, but as mentioned above, it is approximately
It is 0.5mm or less.

The narrower it is, the greater the effect of suppressing burrs, but if it is less than 0.1 mm, the burrs 4 filled in this area during welding will receive a large shear force and generate heat, lowering the molten viscosity and causing burrs to suppress burrs. Problems may occur, such as the burr accommodating protrusion 7 being exceeded or the burr accommodating protrusion 7 being thermally deformed.
Of course, the width t of clearance 8 is 0.1mm all around the circumference.
In industrial production, it is extremely difficult to maintain the width t of the gap 8 with high precision, and if an attempt is made to reduce the width t of the gap 8, the protrusion 7 will come into partial contact with the side wall 1a of another member during bonding, resulting in normal bonding. There is also a practical problem that the conditions cannot be maintained.

Note that the width t of the gap 8 does not need to be constant, and may vary within the above range in the circumferential direction or the axial direction.

The joint does not need to be a plane perpendicular to the axial direction as shown in FIGS. 3 and 4, but may be a conical surface as shown in FIGS. 7 and 8, or a combination thereof.

The protrusions 7 may be provided on either the outside or the inside where burr prevention is required in view of the required performance of the joint, but it goes without saying that they may be provided on both sides as shown in FIG.

The gap 8 for storing burrs needs to be substantially parallel to the rotation axis. To explain this reason, as shown in Figure 5, the gap 8 for storing burrs is
Consider the case where is not parallel to the rotation axis. In FIG. 5, the solid line indicates the state before bonding. If the melting margin at the time of bonding is a, the state after bonding will be as shown by the dotted line. Then, the width t of the gap 8 for storing burrs changes from _tA to _tB . If t _A and t _B are 0.5 mm or less, there is an effect of suppressing burrs throughout the bonding process, but if t decreases during the bonding process as in the example in Figure 5, the generated burrs may be removed externally. Since the extrusion action works, the burr suppression effect becomes smaller.

Note that the height b of the burr storage protrusion must be such that it can sufficiently accommodate the amount of burr generated during bonding. Therefore, the height b is the width t of the gap 8
It can be determined depending on the bonding conditions and the amount of recess a.

Another effect of the burr storage protrusion 7 of the present invention is improved bonding performance. That is, since the burr generated during joining remains in a molten state on the outside of the joint part 3,
During bonding, there is less molten resin flowing out from the bonding surfaces, resulting in higher bonding performance. This effect is effective over the entire range of the width t of the gap 8 for storing burrs from 0.1 to 0.5 mm, but especially when the width W of the joint part is small,
The effect of improving bonding performance is greater when the width t of the gap 8 is 0.2W or less.

The shelf 9 is the joint part 3 of the joint member 1 without the protrusion 7
It is provided on the nearby side wall 1a corresponding to the protrusion 7. shelf 9
are provided at a predetermined distance from the bonding surface 3. That is, the shelf 9 is separated from the joint 3 by the sum of the height b of the protrusion 7 and the expected penetration amount a, that is, a+b. The expected penetration amount a is the height at which the joint portion 3 melts and decreases during joining. When such a joint is joined, the protrusion 7 comes into contact with the shelf 9 when the joining process is near the end. As a result, the pressure applied to the joint surface 3, which was previously applied only to the part W, will now be applied to the width W' of the protrusion, so the pressure applied to the joint surface 3 will be reduced even without changing the pressure applied by the welding machine. It rapidly decreases, and the heat generation at the joint surface also decreases. Therefore, when the protrusion 7 contacts the shelf 9, the melting rate decreases, so that the variation in the height of the joined product becomes smaller. If you choose the joining conditions, protrusion 7
Needless to say, it is possible to prevent the contact surfaces of the shelves 9 from melting. Although it is actually extremely difficult to stop the burr storage protrusion 7 and the mating member 1 at the moment they come into contact, in this method, if the joining time is set a little longer, the pressure can be applied automatically as described above. Since the adjustment function works, it is possible to easily produce bonded products without any burrs or gaps. Note that the shelf 9 only needs to be separated from the protrusion by a predetermined distance, and may have any shape as shown in FIG.

By setting the gap 8 for storing burrs to an appropriate width, the generation of burrs is suppressed, and by providing the shelf 9, there is no gap between the shelf 9 and the protrusion 7 for storing burrs. Since such joining can be carried out easily and reliably, it becomes possible to industrially produce friction-welded products with a beautiful appearance.

The present invention may be implemented either on the inside or outside of the joint, depending on the appearance, or on both sides of the joint 3, as shown in FIG.

The second feature of the present invention is that, as shown in FIG. , grooves 10 are provided. The width of this groove 10 may be the same as the width t of the gap 8 for storing burrs, and the depth may be 0.5 mm or more. The groove 10 has the effect of lengthening the propagation path of heat from the bonding surface 3, which becomes hot during bonding, to the protrusion 7. Therefore, there is thermal efficiency during bonding, saving energy and time required for bonding, and improving bonding performance. The present invention may also be implemented on either the inside or the outside, or on both sides, as shown in FIG. 10, depending on the required performance of the joint.

By implementing the present invention, in rotary friction welding,
In addition to being able to prevent the occurrence of burrs at the joints without damaging the design of the joints,
This has improved bonding performance and made production management easier.

[Brief explanation of drawings]

FIG. 1 is a sketch including a partial cross section of a pair of joining members for rotational friction welding. FIG. 2 is a cross-sectional view of the vicinity of a joint where burr countermeasures have been applied using a conventional technique.
3 and 4 are sectional views of the vicinity of the joint portion showing the first embodiment of the present invention, with FIG. 3 being a sectional view before joining, and FIG. 4 showing a sectional view after joining. FIG. 5 is a cross-sectional view illustrating an example of unfavorable joining. 6 to 9 are sectional views of the vicinity of the joint portion showing other embodiments of the present invention. FIGS. 7 to 9 show the state before joining, and FIG. 6 shows the state after joining. FIG. 10 is a sectional view of the vicinity of the joint showing the second embodiment of the present invention;
Shows the state before joining. 1, 2... Joining member, 1a... Side wall near the joining part 3 corresponding to the inner surface 7a of the burr storage projection, 3...
... joint portion, 4... burr, 5... conventionally known burr storage protrusion, 6... conventionally known burr storage gap, 7... burr storage protrusion of the present invention, 7a... ...Inner wall of burr storage protrusion, 8...Flash storage gap of the present invention, 9...Shelf provided near joint surface 3, 10...Groove, P...pressure force, A...
Direction of rotational movement, t...width of gap for storing burrs,
W... Width of the joint, r ₁ ... Outer radius of the joint, r ₂ ...
...Inner radius of the joint, W'...width of the protrusion, a...expected melting amount, b...height of the protrusion, _tA ...t before welding, _tB ...t after welding.

Claims (1)

[Scope of Claims] 1. Joining members 1 and 2 having circular joint portions are pressed into contact with each other at the joint portion and rotated relative to each other,
During friction and welding, the joint part 3 of the joint member 1
Clearance with nearby side wall 1a is 0.1-0.5mm and 0.2W
A protrusion 7 with a height of b mm is provided in front of the joint part 3 of the joint member 1 over the entire inner circumference, outer circumference, or both circumferences of the joint part 3 so as to have a side surface 7a of 1 mm or less. A friction welding method characterized in that a shelf 9 is provided on the member 2 at a position separated by a + b mm from the joint in correspondence with the protrusion 7: where W: outer radius r ₁ and inner radius r ₂ of the joint (mm) b: Height of protrusion 7 from joint 3 (mm) a: Expected amount of melting (mm) 2 Pressure contact between joint members 1 and 2, which have circular joints, at the joint surface force, relative rotational movement,
When performing friction welding, the clearance between the joining member 1 and the side wall 1a near the joining part 3 is 0.1 to 0.5 mm and 0.2 W.
A protrusion 7 with a height of b mm is provided in front of the joint part 3 over the entire inner circumference, outer circumference, or both peripheries of the joint part 3 of the joint member 1 so that the side surface 7a is less than A friction welding method characterized in that a shelf portion 9 is provided through a groove 10 provided further rearward, and a shelf portion 9 is provided on the joint member 2 at a position separated by a + bmm from the joint portion in correspondence with the protrusion 7. However, W: Difference between outer radius r ₁ and inner radius r ₂ of the joint (mm) b: Height of protrusion 7 from joint 3 (mm) a: Expected amount of melting (mm)