EP3247527A1

EP3247527A1 - Ultrasonic welding method and product obtained with the method

Info

Publication number: EP3247527A1
Application number: EP16740315.3A
Authority: EP
Inventors: Andrea Cirolini; Mauro Maule; Marco ARMIENTO
Original assignee: Ebara Corp
Current assignee: Ebara Corp
Priority date: 2015-01-19
Filing date: 2016-01-18
Publication date: 2017-11-29
Also published as: CN107206543A; BR112017015309A2; TWI687273B; EP3247527A4; CN107206543B; JP6714003B2; JP2018509314A; WO2016117708A1; BR112017015309B1; TW201628749A

Abstract

An ultrasonic welding method that includes the steps of: preparing at least two members made of thermoplastic material, arranging them with respective connecting regions mutually adjacent in a substantially mated manner; transmitting an ultrasonic beam to at least one of the members at the connecting regions; simultaneously with the ultrasonic transmission, applying a pressure to the members, pressing them one against the other in order to keep the connecting regions in mutual contact. The particularity of the present invention resides in that the connecting regions include curvilinear portions that mutually mate and in that, prior to the preparation of the members, respective mutually mating welding surfaces are defined on the members; such mutually mating welding surfaces make the curvilinear portions at least partially discrete. The invention also relates to a product manufactured with the method.

Description

DESCRIPTION

Title of the Invention

ULTRASONIC WELDING METHOD AND PRODUCT OBTAINED WITH THE METHOD

Technical Field

The present invention relates to an ultrasonic welding method and to a product obtained with the method.

Background Art

As is known, ultrasonic welding is a commonly used technique for assembling parts made of plastics.

In practice, ultrasonic welding occurs by applying to the parts to be welded a variable normal load and by vibrating one part with respect to the other by virtue of adapted devices capable of generating a vibration with an ultrasonic frequency.

This intense vibration, transmitted by a so-called sonotrode, generates heat, which melts the material, thereby welding the two parts.

Summary of the Invention

Technical Problem

The reliability and correct application of this technique, however, require following a series of measures, the first of which is that the force applied and the direction of the vibrations must necessarily be perpendicular to the welding joints.

Therefore, if the welding joints between the parts extended along curves or shaped surfaces, the ultrasonic technique is difficult if not impossible to apply.

In such cases it is therefore necessary to resort to other methods, such as for example friction welding.

Friction welding is a technique whereby the parts are welded by means of the friction that is generated as a consequence of a relative motion, for example a rotation, between the parts to be welded, combined with the application of pressure.

However, friction welding is not very precise and causes welding flash that is incompatible with many applications. As an alternative, it is possible for example to resort to laser welding, whereby a laser beam melts the material and creates the welded joints.

However, the laser beam welding technique is complex and generally can only be performed by means of robots which require high investment costs.

In addition to this, it should be considered that the times, and accordingly the costs, for performing welds by laser may be excessive.

Advantageous Effects of the Invention

The aim of the invention is to solve the problems described above, providing an ultrasonic welding method that allows to weld two or more components even when the connecting regions include curvilinear portions.

Within the scope of this aim, a particular object of the invention is to provide a method that allows to weld at connecting regions that are substantially parallel to the direction of the ultrasonic beam transmitted by the sonotrode.

Another particular object of the invention is to propose a method that allows to manufacture a diffuser of a fluid-operated pump or any other product made of two or more members that are welded at connecting regions that include curvilinear portions.

Another object of the invention is to provide a method that ensures highly reliable and repetitive welds.

Another object of the invention is to propose a method that allows to fully exploit the productive potential of ultrasonic welding machines.

Solution to the Problem

This aim, these objects and others that will become better apparent hereinafter are achieved by an ultrasonic welding method comprising the steps of:

preparing at least two members made of thermoplastic material by positioning them with respective connecting regions mutually adjacent in a substantially mated manner;

transmitting an ultrasonic beam to at least one of said members at said connecting regions;

concurrently to the step of transmitting the ultrasonic beam, applying a pressure to said members, pressing them against each other in order to maintain said connecting regions in mutual contact; characterized in that:

said connecting regions comprise mutually matching curvilinear portions;

prior to the step of preparing said members, said method comprising the step of forming matching welding surfaces on said members, making said curvilinear portions at least partially discrete.

According to a further aspect, the present invention provides a product comprising at least two members that can be welded by means of an ultrasonic beam transmitted at respective connecting regions, said connecting regions having curvilinear portions; characterized in that said members comprise mutually matching welding surfaces that make said curvilinear portions at least partially discrete.

Brief Description of the Drawings

Further characteristics and advantages will become better apparent from the description of preferred but not exclusive embodiments of an ultrasonic welding method and of a product obtained with the method, according to the invention, illustrated by way of non-limiting example in the accompanying drawings, wherein:

Figure 1 is a schematic sectional view of a generic product obtained by means of the method according to the invention;

Figure 2 is a top view of a diffuser of a fluid-operated pump obtained by means of the method according to the invention;

Figure 3 is a sectional view taken along the plane Ill-Ill of Figure 2;

Figure 4 is a perspective view of a component of the diffuser;

Figure 5 is a top view of the component of the preceding figure;

Figure 6 is a sectional view taken along the plane VI-VI of Figure 5;

Figure 7 is a top view of another component of the diffuser;

Figure 8 is a sectional view taken along the plane VIII-VIII of Figure 7.

Description of the Embodiments

With reference to the cited figures, the present invention relates to a method for ultrasonic welding members made of thermoplastic material to be mutually assembled. More particularly, the method is conceived to perform ultrasonic welding between at least one first member 1 and at least one second member 2, which have connecting regions that include curvilinear portions that mutually mate and are designated respectively by the reference numerals 3 and 4.

According to the invention, the method comprises defining mutually matching welding surfaces on the first member 1 and on the second member 2 and making the curvilinear portions of the welding surfaces at least partially discrete.

Conveniently, said welding surfaces are defined respectively at the first connection region 3 and at the second connecting region 4 before performing the welding operations.

According to a preferred but not exclusive embodiment, the welding surfaces are substantially perpendicular to the ultrasonic beam used to perform welding and are conceived so as to interrupt the continuity of the curvature of the curvilinear portions.

In the illustrated example, the welding surfaces are defined respectively by a first plurality of steps 5 and by a second plurality of steps 6.

In the specific case, the steps 5 are mutually adjacent, and so are the steps 6; however, according to a further embodiment, the steps may be spaced.

In practice, each step 5 is composed of a welding surface 5a and of a connecting surface 5b, the welding surface 5a being substantially perpendicular to the ultrasonic beam 50 used for welding.

Likewise, each step 6 is composed of a welding surface 6a, which is substantially perpendicular to the ultrasonic beam 50 used for welding, and of a connecting surface 6b.

In the illustrated example, the connecting surfaces 5b and 6b are substantially parallel to the ultrasonic beam 50 used for welding, but different shapes may be used without departing from the inventive concept.

Conveniently, the welding surfaces 5a substantially mate with the corresponding welding surfaces 6a, while the connecting surfaces 5b substantially mate with the corresponding connecting surfaces 6b. It should be noted that the steps 5 and 6 are made taking care that the thicknesses of the first member 1 and of the second member 2 are sufficient to obtain reliable welded joints.

Preferably, the steps 5 and 6 are provided during the molding of the members 1 and 2. - ^{. . . .} .^.

As an alternative, the steps 5 and 6 can be provided by removing material from the connecting regions 3 and 4.

Once the steps 5 and 6 have been formed, it is possible to perform the actual welding operations, which begin by arranging the first member 1 and the second member 2 so that the steps 5 and 6 are mutually adjacent; in particular, the welding surfaces 5a are arranged adjacent to the corresponding welding surfaces 6a.

At this point, by means of a sonotrode, a tool that creates ultrasonic vibrations, an ultrasonic beam is transmitted to at least one of the two members 1 and 2 substantially at the steps 5 and 6.

The other member is conveniently inserted in a fixed die, known as anvil.

Simultaneously, pressure is applied to the two members 1 and 2, pressing them against each other so as to keep the steps 5 and 6 in mutual contact.

It is very important to point out to that by performing the method according to the invention the ultrasonic beam and the applied pressure are substantially perpendicular to the welding surfaces 5a and 6a.

The presence of the welding surfaces 5a and 6a therefore allows to effectively transmit the ultrasonic beam and the thrust, ensuring the good result of the welding operation.

Furthermore, this arrangement prevents mutual slippages and/or deformations of the two members 1 and 2.

The present invention also relates to a product obtained by means of the method described and illustrated above.

This product includes two or more members that are welded by means of an ultrasonic beam transmitted at respective connecting regions. According to the invention, at the connecting regions, the members include respective mutually mating welding surfaces, which are conceived in such a manner as to make the curvilinear portions of the connecting regions at least partially discrete.

Figures 2 to 8 illustrate a practical embodiment of a product constituted by a d iff user 100 of a fluid-operated pump.

It is evident to the person skilled in the art that several different products may have features that are substantially equivalent without departing from the scope of the invention.

The diffuser 100 comprises a first member 101 and a second member 102, which are joined by means of the ultrasonic welding method according to the invention.

The first member 101 comprises a first body 110 centrally provided with a through hole 111 and laterally delimited by a first wall 112 that substantially has the profile of a quadric surface portion.

Vanes 113 extend from the first wall 112 and are angularly distributed around the axis of symmetry of the first body 110.

Conveniently, the vanes 113 are curved so as to form, together with the second member 102, radially arranged ducts.

The second member 102 comprises a substantially cylindrical second body 120, which is centrally provided with a concavity 121 that accommodates at least one portion of the first member 101.

Conveniently, the concavity 121 has a shape that is substantially complementary to the envelope of the vanes 113.

In fact, the two members 101 and 102 are intended to be mutually joined in a manner wherein the edges 114 of the vanes 113 mate with the surface of the concavity 121 so as to define the above cited ducts.

According to the invention, the first member 101 and the second member 102 include respective welding surfaces, which mate with each other and make the curvilinear portions of the connecting regions of the two members 101 and 102 at least partially discrete. Such welding surfaces are defined respectively by a first plurality of adjacent steps 105 and by a second plurality of adjacent steps 106.

The first steps 105 are formed substantially at the edges 114 of the vanes 113, while the second steps 106 are provided on the surface of the concavity 121 with a pattern that matches the pattern of the first steps 105.

In practice, each step 105 is composed of a welding surface 105a, which is substantially parallel to a base of the first body 110, and a connecting surface 105b.

Likewise, each step 106 is composed of a welding surface 106a, which is substantially parallel to a base of the second body 120, and a connecting surface 106b.

Conveniently, at the welding surface 105a of each step 105 there is a protrusion 115 which, during welding, has the task of concentrating the energy provided by the sonotrode.

As an alternative, the protrusion might be formed at the welding surface 106a of each step 106.

As mentioned earlier, the diffuser 100 is made by separately manufacturing the two members 101 and 102 and by joining them at a later time, so that the welding surfaces 105a are welded to the corresponding welding surfaces 106a.

In practice, the two members 101 and 102 are joined by matching the welding surfaces 105a on the corresponding welding surfaces 106a, and the connecting surface 105b on the corresponding connecting surface 106b, and by transmitting an ultrasonic beam to a base of the first member 101 , or of the second member 102; pressure is applied simultaneously.

It is immediately appreciated that the welding surface 105a of each step 105 is substantially perpendicular to the ultrasonic beam used for welding.

Likewise, the welding surface 106a of each step 106 is substantially perpendicular to the ultrasonic beam used for welding.

According to a further aspect of the invention, also the problem of phasing the two members 101 and 102 during welding is solved. Such problem is solved by forming adapted protrusions 116 on one of the members and corresponding seats 122 on the other member. The protrusions 116 are adapted to interlock in as many corresponding seats 122 provided on the other member.

At this point it is evident that the present invention achieves the intended aim and objects.

Namely, the invention allows to make ultrasonic welds at connecting regions that include curvilinear portions.

This method also allows to utilize the ultrasonic welding technique at connecting regions that are substantially parallel to the direction of the ultrasonic beam that is used.

A practical application of the method, for example, is the manufacturing of a diffuser of a fluid-operated pump by ultrasonic welding two components at connecting regions that include curvilinear portions.

This method, and the products provided with it, are also particularly advantageous from a purely economic standpoint.

In practice it has been found that the ultrasonic welding method and the product obtained with the method, according to the invention, fully achieve the intended aim and objects.

This application claims the priority of Italian Patent Application No. VI2015A000013, filed on January 19, 2015, the subject matter of which is incorporated herein by reference.

Claims

1. An ultrasonic welding method comprising the steps of:

concurrently to the step of transmitting the ultrasonic beam, applying a pressure to said members, pressing them against each other in order to maintain said connecting regions in mutual contact;

characterized in that:

said connecting regions comprise mutually matching curvilinear portions;

2. The method according to the preceding claim, characterized in that said welding surfaces are substantially perpendicular to said ultrasonic beam and are connected with said curvilinear portions so as to interrupt the continuity in the curvature of the curvilinear portions.

3. The method according to one or more of the preceding claims, characterized in that said welding surfaces are mutually adjacent.

4. The method according to one or more of the preceding claims, characterized in that said welding surfaces are provided while molding said members.

5. The method according to one or more of the preceding claims, characterized in that said welding surfaces are provided by removing material from said members.

6. The method according to one or more of the preceding claims, characterized in that at least a portion of said welding surfaces comprises protrusions adapted to concentrate the energy transmitted by said ultrasonic beam.

7. The method according to one or more of the preceding claims, characterized in that said members comprise a phasing means; said phasing means comprising at least a pair of protrusions formed on one of said members and adapted to interlock in as many corresponding seats formed on the other member.

8. A product comprising at least two members that can be welded by means of an ultrasonic beam transmitted at respective connecting regions, said connecting regions having curvilinear portions; characterized in that said members comprise mutually matching welding surfaces that make said curvilinear portions at least partially discrete.

9. The product according to claim 8, characterized in that said welding surfaces are substantially perpendicular to said ultrasonic beam and are connected to said curvilinear portions so as to interrupt their continuity of curvature.

10. The product according to claim 8, characterized in that said welding surfaces are mutually adjacent.

11. The product according to claim 8, characterized in that said members are components of a diffuser of a fluid-operated pump; said first member comprising a first body centrally provided with a through hole and laterally delimited by a first curvilinear wall; vanes extending from said first wall and being angularly distributed around the axis of symmetry of said first body; said second member comprising a second substantially cylindrical body that is centrally provided with a concavity that is adapted to accommodate at least one portion of said first body; said concavity having a shape that is substantially complementary to the envelope of said vanes; said members comprising welding surfaces which mutually match and are formed substantially at the edges of said vanes and on the surface of said concavity so as to make them at least partially discrete.