GB1566531A

GB1566531A - Ultrasonic welding

Info

Publication number: GB1566531A
Application number: GB1670/78A
Authority: GB
Original assignee: Polyplastics Co Ltd
Current assignee: Polyplastics Co Ltd
Priority date: 1977-01-17
Filing date: 1978-01-16
Publication date: 1980-04-30
Also published as: IT7819311A0; FR2377265A1; BR7800238A; JPS5388883A; DE2801699A1; NL7800553A; BE862833A; AU509518B2; AU3210977A; JPS622973B2

Description

(54) ULTRASONIC WELDING (71) We, POLYPLASTICS CO. LTD., a Japanese Company, of 30, 2-chome, Azuchimachi, Higashi-ku, Osaka-shi, Japan, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a method of ultrasonically welding together two components each of a material capable of being so welded. In particular the components are of a synthetic plastics material.

In the assembly of a product in which the two components to be welded together are resiliently urged apart, for example by a spring disposed between them, problems occur in performing the welding step accurately, efficiently and economically in that it is difficult to pre-locate the two components in the desired juxtaposition prior to and during the welding step.

It is previously known to pre-locate two components prior to an ultrasonic welding step by forming them to be interengageable with one another by an interference fit. For example one component may have a male element which is an interference fit within a female element of the second component.

Such an arrangement is not always satisfactory when the two components as preassembled are resiliently urged apart.

For example the adequacy of the interference fit depends upon the accuracy with which the two components are preformed. Alternatively, one of the components may be shrink fitted on the other to effect the pre-location, but this involves the additional complication of a heating or cooling step. Alternatively again, an additional member may be employed to effect the pre-location. For example clamp or peg means may be employed to hold the two components in interengagement prior to the welding step. The invention aims to provide a viable alternative in view of these and other problems.

According to this invention there is provided a method of ultrasonically welding two components each of a material capable of being so welded in which the two components are so formed that they can be interlocked simply by being bodily manipulated relative to one another, said two components being so interlocked prior to an ultrasonic welding step to effect writing of the components one with the other.

The pre-location step can be accomplished in a number of ways. For example the two components may be formed se as to be interengageable by a snap fixing whereby the components are interlocked by interengaging abutments provided on the respective members. The joint between the components so form on pre-location may resemble any joint known in joinery, in particular a bead joint, a scarf joint or a dovetail. Alternatively, pre-location may be achieved by a screwed joint or by a bayonet joint. However, in each case the pre-location will be achieved by a manipulation of the two components bodily to lock them together and will avoid the necessity of providing additional locking members such as pegs or clamps.

Preferably, once the pre-location has been achieved by the interlocking joint, the welding step will be so carried out as to apply the ultrasonic vibrations to the joint so that the two components become umted or bonded at or in the region of the joint. In some cases after the pre-location step, pressure may be applied to effect relative movement of the two components before the ultrasonic vibrations are generated to weld the components together.

In the drawings: Figures 1A, 1B and 1C illustrate by diagrammatic sectional view, steps in the production of a diaphragm valve equipped with two components pre-located by a snap fixing and subsequently bonded together by ultrasonic welding, Figure l A showing the components before the pre-location, that is, the pre-assembly, Figure 1B showing pre-location, and Figure 1C showing the final product, that is, after the ultrasonic welding.

Figures 2A, 2B and 2C are schematic sectional views showing steps in the manufacture of a check valve, Figure 2A showing the components before pre-location, Figure 2 B showing the pre-assembly after pre-locaxion by snap fixing, but before the ultrasonic welding, and Figure 2C showing the final product, that is, after the ultrasonic welding.

Figure 3(a) is a detailed sectional view showing part of the snap joint as applied to one of the components of the valve; and Figure 3(b) is a detailed sectional view showing a corresponding snap joint as applied to a mating component of the valve.

Referring to the drawings, the method of the present invention will be explained in further detail with reference to body components 1 and 2 which are repelled from one another resiliently, for example by force of the spring 7 and which yet are required to be joined together by ultrasonic welding.

In the assembly of products having spring mechanism such as a diaphragm valve (shown in Figure 1), a check valve (shown in Figure 2), if it is difficult to maintain a body component 1 correctly positioned in abutment with a body component 2 because of the spring 7 of a long free length, a fault percentage of the resulting products would naturally increase since precise positioning of the components is extremely difficult in the pre-assembly operation prior to the ultrasonic welding.

In the method of the present invention however, the body components 1 and 2 of a shaped article are provided with an interlocking under-cut structure during moulding, as shown in Figures 1A, 2A and 3, so that after the components have been placed juxtaposed in position they may be manipulated into interlocking engagement before ultrasonic welding, as shown in Figures 1B and 2B. By this arrangement the components are located in correct positional relationship before the ultrasonic welding, whereby the welding operation becomes extremely easy and provides an extremely high yield.

In accordance with the conventional method, all the internal components must be filled on the work table of the ultrasonic welding machine to thereby prolong the work time on the work table as much, and lower the productivity of the same. In the method of the present invention, on the other hand, the pre-assembly up to the snap-in operation can be carried out at a different place by different labourers so that an operator of the ultrasonic welding machine is liberated from the troublesome pre-assembly operation and thus capable of concentrating exclusively on the welding operation and improving the operational efficiency.

In Figures 1A and 2A, the arrows indicate the direction of manipulation to effect snap fixing, while in Figures 1B and 2B the arrows indicate application of pressure which is applied to effect movement of the components relative to one another immediately prior to bonding by ultrasonic energy.

Figures 3(a) and 3(b) are partial schematic views showing, respectively, the detail of the snap joint formed by interlocking engagement of parts 3 and 4, wherein an undercut engagement A d2 is adapted to be manipulated into engagement by an abutment having a dimension A d2, so that the parts 3 and 4 are interlocked. The symbol Adi indicates the thickness of the weld fillet 5. The pre-location in the method of the present invention may be practised by pre-locating the two components to be joined together by screwing one component transversely into the other or by forming a joint as in a bayonet fixing. If, however, the interlocking of the parts 3 and 4 as depicted in the drawings is accomplished simply by pushing the abument on the part .3 past the abutment on the part 4, then this will involve resilient flexing of one or both of the components during the manipulation to effect interlocking for pre-location.

As will be seen from Figures 1C and 2C the welding is effective to bond the two components together in the region of the mating joint between parts 3 and 4.

WHAT WE CLAIM IS: 1. A method of ultrasonically welding two components each of a material capable of being so welded in which the two components are so formed that they can be interlocked simply by being bodily manipulated relative to one another, said two components being so interlocked prior to an ultrasonic welding step to effect uniting of the components one with the other.

2. A method according to claim 1 wherein the two components are interengageable by a snap fixing so as to bring abutments provided on the components respectively into interlocking relationship one behind the other.

3. A method according to claim 2 wherein the manipulation required to bring the abutments on the respective components into interlocking relationship involves resilient flexing of one or both components.

4. A method according to claim 1 wherein the joint effected by the manipulation to

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. before the pre-location, that is, the pre-assembly, Figure 1B showing pre-location, and Figure 1C showing the final product, that is, after the ultrasonic welding. Figures 2A, 2B and 2C are schematic sectional views showing steps in the manufacture of a check valve, Figure 2A showing the components before pre-location, Figure 2 B showing the pre-assembly after pre-locaxion by snap fixing, but before the ultrasonic welding, and Figure 2C showing the final product, that is, after the ultrasonic welding. Figure 3(a) is a detailed sectional view showing part of the snap joint as applied to one of the components of the valve; and Figure 3(b) is a detailed sectional view showing a corresponding snap joint as applied to a mating component of the valve. Referring to the drawings, the method of the present invention will be explained in further detail with reference to body components 1 and 2 which are repelled from one another resiliently, for example by force of the spring 7 and which yet are required to be joined together by ultrasonic welding. In the assembly of products having spring mechanism such as a diaphragm valve (shown in Figure 1), a check valve (shown in Figure 2), if it is difficult to maintain a body component 1 correctly positioned in abutment with a body component 2 because of the spring 7 of a long free length, a fault percentage of the resulting products would naturally increase since precise positioning of the components is extremely difficult in the pre-assembly operation prior to the ultrasonic welding. In the method of the present invention however, the body components 1 and 2 of a shaped article are provided with an interlocking under-cut structure during moulding, as shown in Figures 1A, 2A and 3, so that after the components have been placed juxtaposed in position they may be manipulated into interlocking engagement before ultrasonic welding, as shown in Figures 1B and 2B. By this arrangement the components are located in correct positional relationship before the ultrasonic welding, whereby the welding operation becomes extremely easy and provides an extremely high yield. In accordance with the conventional method, all the internal components must be filled on the work table of the ultrasonic welding machine to thereby prolong the work time on the work table as much, and lower the productivity of the same. In the method of the present invention, on the other hand, the pre-assembly up to the snap-in operation can be carried out at a different place by different labourers so that an operator of the ultrasonic welding machine is liberated from the troublesome pre-assembly operation and thus capable of concentrating exclusively on the welding operation and improving the operational efficiency. In Figures 1A and 2A, the arrows indicate the direction of manipulation to effect snap fixing, while in Figures 1B and 2B the arrows indicate application of pressure which is applied to effect movement of the components relative to one another immediately prior to bonding by ultrasonic energy. Figures 3(a) and 3(b) are partial schematic views showing, respectively, the detail of the snap joint formed by interlocking engagement of parts 3 and 4, wherein an undercut engagement A d2 is adapted to be manipulated into engagement by an abutment having a dimension A d2, so that the parts 3 and 4 are interlocked. The symbol Adi indicates the thickness of the weld fillet 5. The pre-location in the method of the present invention may be practised by pre-locating the two components to be joined together by screwing one component transversely into the other or by forming a joint as in a bayonet fixing. If, however, the interlocking of the parts 3 and 4 as depicted in the drawings is accomplished simply by pushing the abument on the part .3 past the abutment on the part 4, then this will involve resilient flexing of one or both of the components during the manipulation to effect interlocking for pre-location. As will be seen from Figures 1C and 2C the welding is effective to bond the two components together in the region of the mating joint between parts 3 and 4. WHAT WE CLAIM IS:

1. A method of ultrasonically welding two components each of a material capable of being so welded in which the two components are so formed that they can be interlocked simply by being bodily manipulated relative to one another, said two components being so interlocked prior to an ultrasonic welding step to effect uniting of the components one with the other.

bring the two components into interlocked pre-location is either a screw joint or a bayonet joint.

5. A method according to claim 1 wherein the joint effected by the manipulation to bring the two components into interlocked pre-location resembles a bead joint, a scarf joint, or a dovetail joint, in each case having been achieved by snap fixing involving during the manipulation, resilient flexing of one or both components.

6. A method according to claim 1 wherein once the pre-location has been achieved by the interlocking, pressure is applied to effect relative movement of the two components before the ultrasonic vibrations are generated to weld the components together.

7. A method according to any of the preceding claims, wherein the welding between the components is applied in those regions of the components where they have been previously interlocked by the pre-location step.

8. A method of ultrasonically welding two components according to claim 1 and substantially as hereinbefore described with reference to the accompanying drawings.

9. A product having two components welded ultrasonically by the method defined in any preceding claim.