WO2021124180A1

WO2021124180A1 - Manual ultrasonic welder

Info

Publication number: WO2021124180A1
Application number: PCT/IB2020/062084
Authority: WO
Inventors: Camillo Rena
Original assignee: Comimport Italia Srl
Priority date: 2019-12-19
Filing date: 2020-12-17
Publication date: 2021-06-24
Also published as: EP4076907A1; IT201900024892A1

Abstract

Described is an ultrasonic welding machine (100). The manual welding machine (100) comprises a welding assembly (10) configured to be placed in contact with a piece to be welded and operable to ultrasonically weld a piece with which it is placed in contact, a support assembly (20) to which the welding assembly (10) is connected to be supported by it, and a control assembly (30) connected to the welding assembly (10) and the support assembly (20) and configured to detect a stress exerted between the welding assembly (10) and the support assembly (20). In particular, the control assembly (30) is further configured or programmed to inhibit the actuation of said welding assembly (10) and/or deactivate said welding assembly (10) if said stress does not satisfy a predefined condition.

Description

MANUAL ULTRASONIC WELDER

TECHNICAL FIELD

This invention relates generally to the field of ultrasonic welding machines, and in particular relates to manual ultrasonic welding machines.

BACKGROUND ART

Ultrasonic welding machines are currently known in the field of welding machines which are mainly designed to weld plastic components or parts. In particular, there are prior art manual ultrasonic welders designed mainly for the recovery of plastic components or parts deriving from industrial welding lines or designed for serial welding activities of low frequency for which the need for operational flexibility and ergonomics makes it inadvisable or impossible to use a fixed industrial ultrasonic welding machine.

The prior art manual ultrasonic welding machines are configured to control several parameters intrinsic to the same welding process, such as energy and power delivered, welding time, ultrasonic amplitude to ensure a certain degree of reliability or quality of the welding result.

However, the author of the invention has noted that the quality of the result of the welding performed with the prior art manual ultrasonic welding machines is, however, variable.

These, in fact, in spite of the high flexibility given by the manual use by the operator, require from the latter a high degree of attention and experience in order to obtain an effective welding; in fact the quality of the welding will be considerably affected by the speed of movement on the piece of the welding machine, to the thrust exerted by the operator on the piece and to the constancy of the latter, as well as the positioning of the welding head itself in relation to the pieces to be welded.

This sometimes results in the need for re-processing of previously welded components to resume welding or repeat the welding again, resulting in slowdowns or delays in production.

SUMMARY OF THE INVENTION

The problem forming the basis of the invention is therefore to propose a portable welding machine for plastic material which overcomes the above- mentioned drawbacks.

The aim of the invention is therefore to propose an ultrasonic manual welding machine which improves the effectiveness of the prior art ultrasonic manual welding machines.

In particular, the author of the invention has found that the quality of the result of ultrasonic welding, performed with manual welding machines, also depends on the pressure or force with which the portion of the welding machine, intended to be placed on the piece to be welded, is held in contact with the latter.

For this reason, within this aim, the invention proposes to make the activation and powering of the portion of the welding machine, intended to be placed on the piece to be welded, dependent on the satisfaction of a predetermined stress condition between this portion and the piece to be welded with which it is placed in contact.

Said predefined condition essentially represents an "optimal" support or thrust condition of the portion of the welding machine intended to be placed against the piece to be welded and the latter.

Advantageously, in addition to the control of the traditional parameters intrinsic to the operation of the manual welding machine the manual welding machine according to the invention controls the interaction between it and the piece to be welded, in terms of stress, pressure or thrust, allowing the welding operation when said predefined condition is satisfied, that is, when the interaction between the welding machine and the piece to be welded is such as to ensure a good quality weld.

This aim, as well as these and other aims which will emerge more fully below are achieved by a portable welding machine for plastic material according to the attached independent claim 1.

Advantageous aspects of a manual ultrasonic welding machine are described in the attached dependent claims.

Said claims, as filed, are incorporated herein for explicit reference. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows a simplified diagram of a manual ultrasonic welding machine. Figure 2 shows a cross-section view of a component relative to the manual welding machine of Figure 1.

Figure 3 shows an enlargement of the detail V of Figure 2. DETAILED DESCRIPTION

With particular reference to the accompanying drawings, an ultrasonic manual welding machine is indicated in its entirety with the reference numeral 100.

The manual welding machine 100, according to the invention, comprising: a welding assembly 10 configured to be placed in contact with a piece to be welded and operable to ultrasonically weld a piece with which it is placed in contact; a support assembly 20 to which the welding assembly 10 is connected to support the latter; - a control assembly 30 electrically connected to the welding assembly 10 and the support assembly 20 and configured to detect a stress exerted by the welding assembly 10 on the support assembly 20, or vice versa; wherein the control assembly 30 is further configured or programmed to inhibit the actuation, that is, activation, of said welding assembly 10 and/or deactivate said welding assembly 10 if said stress does not satisfy a predefined condition.

It follows that, according to the invention, the welding assembly 10 may be activated and powered only upon satisfaction of the predefined stress condition exerted between the welding assembly 10 and the control assembly 20.

That is to say, the welding assembly 10 can be rendered, and maintained, operational only if the operator, by means of the welding machine 100, exerts on the piece to be welded a stress sufficient to satisfy said predefined condition, which may be defined in such a way as to correspond to the stress necessary to obtain an optimal welding.

In fact, this stress, which the operator exerts through the welding machine 100 on the piece to be welded, is clearly that which is transmitted between the support assembly 20 and the welding assembly 10.

Preferably, the control assembly 30 is further configured or programmed to control the actuation of said welding assembly 10 and/or the deactivation of said welding assembly 10 depending on one or more parameters such as the energy or the power transmitted by means of the welding assembly 10 to the piece to be welded, the welding time, the frequency of ultrasonic vibrations of the welding assembly 10.

The predefined condition can be satisfied - if said stress is greater than a lower threshold and less than an upper threshold or

- if it is less than an upper threshold.

In other words, the predefined condition may be satisfied if the stress is between a lower threshold and an upper threshold or if it is less than an upper threshold.

Thus, the predefined condition may be satisfied if said stress is greater than a lower threshold to ensure that the stress exerted between the welding assembly 10 and the support assembly 20, and thus by the welding machine 100 on the piece, is greater than the minimum threshold which may be set at a minimum stress value to achieve a good quality weld

Alternatively, said predefined condition may be met if the stress exerted between the welding assembly 10 and the support assembly 20 does not exceed the upper threshold which may be set at a stress value at which, or above which, undesirable deformation or damage to the piece to be welded could occur.

Or, again, said predefined condition may be satisfied if the stress between the welding assembly 10 and the support assembly 20 is simultaneously lower than the upper threshold and greater than the lower threshold. In this case, both of the above-mentioned advantages are pursued, that is, both that of preventing the operator from exerting excessive stress on the piece to be welded, for example which could deform or damage the piece itself, and that of preventing the welding pressure from being insufficient to carry out a good quality weld.

The control assembly 30 may be configured or programmed to deactivate said welding assembly 10, and simultaneously may report an incorrect weld in the case of automatic welding, if said stress does not satisfy said predefined condition continuously for a first predefined period of time. This means that the welding assembly 10 can be activated or kept active only if the stress transmitted between the welding assembly 10 and the support assembly 20, that is, the stress that the operator exerts by means of the welding machine 100 on the piece to be welded, remains such as to satisfy said predefined condition except for possible time intervals of shorter duration than said first period.

In this way, if said stress does not meet said predefined condition for a time interval of less than a first predefined time period, activation of the welding assembly 10 may be suspended or interrupted to avoid continuing welding under conditions which do not meet said predefined condition. The control assembly 30 may further be configured to emit an alarm signal if said stress does not satisfy said predefined condition continuously for a second preset period of time which is less than said first period of time, to signal to the operator the imminent deactivation of the welding assembly 10.

The difference between the first period of time and the second period of time may consist of a period of time sufficient for the operator to modify the stress exerted by the welding machine 100 on the piece to be welded, so as to return to an operating condition in which the stress transmitted between the support assembly 20 and the welding assembly 10 returns to satisfy said predefined condition before the first period of time has elapsed, so as to avoid deactivation of the welding machine 100.

For example, the control assembly 30 may comprise a signalling unit 33 designed for emitting said alarm signal, for example in the form of an acoustic signal and/or a luminous signal. The control assembly 30 may comprise a stress detector 31.

In this way, the control assembly 30 may be able to measure or quantify the stress between the welding assembly 10 and the support assembly 20. Preferably, the stress detector 31 may be a force transducer, such as, for example, a load cell, or a pressure transducer. The force transducer may detect the force exerted or transmitted by the welding assembly 10 to the support assembly 20.

Advantageously, in this way, the control assembly 30 is able to detect the force which the welding assembly 10 exerts or transmits to the support assembly 20, regardless of the area over which said force acts. The welding machine 100 may further comprise a generator assembly 40 connected to said welding assembly 10 to supply power thereto, for example, the generator assembly 40 is connected to the welding assembly 10 by means of a power cable 41.

The generator assembly 40 may be configured to generate ultrasonic vibrations at a power which may be substantially equal to 800 W with a frequency which may be substantially equal to 40 kHz.

In addition, the control assembly 30 may include a control assembly 32 connected to said stress detector 31 and configured to control said generator assembly 40.

Advantageously, the generator assembly 40 is therefore controlled by said control assembly 32 according to the stress detected by the stress detector 31. The support assembly 20 may comprise a bottom wall 212 and a spacer 22 which abuts against the welding assembly 10. In more detail, the support assembly 20 may comprise at least one perimeter wall 211 which acts in conjunction with said bottom wall 212 to define a housing 21.

Said housing 21 may be configured to contain the spacer 22, the stress detector 31 , and to partially house the welding assembly 10. The stress detector 31 may make contact with the bottom wall 212 of the housing 21 and with said spacer 22 to detect a stress tending to bring the welding assembly 10 closer to the bottom wall 212.

In other words, the stress detector 31 may be abutted against the bottom wall 212 and the spacer 22. Since the spacer 10 is also abutted against the welding assembly 10, when the latter is subjected to a stress which tends to bring it closer towards the bottom wall 212 of the support assembly 20, the spacer 22 may transmit this stress to the stress detector 31.

Preferably, the spacer 22 may be made of a vibration-dampening material The spacer 22 may therefore dampen or absorb the vibrations to which it is subjected by the welding assembly 10.

Thus, advantageously, the spacer 22 may be able to prevent transmission of vibrations to the stress detector 31 and, consequently, may enable accurate stress detection by the stress detector 31.

The welding assembly 10 may extend predominantly along a first direction of extension A between a front region 10b, designed for being placed in contact in use with a piece to be welded, and a bottom region 10a.

The welding assembly 10 may further comprise an abutment element 13, interposed between said bottom region 10a and said front region 10b, extending in a plane a incident to said first direction of extension A. The spacer 22 may be configured in a cup-shape, having a base wall 222 and a side wall 221 connected together.

The spacer 22 may define between the base wall 222 and the side wall 221 a seat 223 designed for receiving the bottom region 10a of the welding assembly 10.

In particular, the base wall 222 of the spacer 22 may face the bottom wall 212 of the housing 21 and may make contact with the stress detector 31, whilst the side wall 221 of the spacer 22 may make contact with the abutment element 13. That is, the side wall 221 may abut or make contact against the abutment element 13.

The contact between the side wall 221 and the abutment element 13 may allow stress to be transferred from the welding assembly 10 to the base wall 222 of the spacer 22 and from this to the base wall of the spacer 22. In turn, the base wall 222 of the spacer 22 may transmit the stress to the abutment element 13.

More in detail, the welding assembly 10 may comprise an ultrasonic emitter 11, which may be powered at a predefined frequency to generate energy in the form of vibration, and a sonotrode 12, coupled in a removable fashion to the emitter 11 to transmit, to a piece to be welded, energy received from the emitter 11 in the form of vibration.

The emitter 11 may extend, predominantly along said first direction of extension A, between a bottom region 112 and a coupling region 111. The bottom region 112 defines the bottom region 10a of the welding assembly 10 and is received in the seat 23 formed by the spacer 22.

The abutment element 13 may be interposed between the bottom region 112 and the coupling region 111 of the emitter 11.

The abutment element 13 may be an integral part of the emitter 11. The emitter 11 may be connected to the generator assembly 40, for example by means of the power cable 41 , to be powered by it.

In such a case, the base wall 222 of the spacer may be a wall having a through hole to allow passage of the power cable 41.

The emitter 11 may be a two-ceramic emitter having a power substantially between 500 W and 5000 W for example equal to 800 W with a nominal working frequency substantially between 20 kHz and 40 kHz for example equal to 40 KHz.

The sonotrode 12 may extend along said first direction of extension A between a coupling region 122, configured to be coupled to the coupling region 111 of the emitter 11 , and a front region 121 , coincident with the front region 10b of the welding assembly 10.

The front region 121 may comprise a welding end which may be, for example, multi-tipped for projection welding or may have a rounded shape for riveting plastic tubing so as to perform nailing or riveting.

In addition, the support assembly 20 may include a clamping element 23.

The clamping element 23 may be configured to abut against the abutment element 13 of the emitter 11 on the opposite side from the side wall 221 of the spacer 22 in said first direction of extension A. The clamping element 23 may be configured to provide a mechanical connection between the spacer 22 and the stress detector 31. Advantageously, the clamping element continuously maintains contact between the spacer 22 and the stress detector 31.

More in detail, said clamping element 23 may be coupled to the perimeter wall 211 of the housing 21 on the opposite side with respect to the bottom wall 212. The clamping element 23 may comprise a through opening through which the coupling region 111 of the emitter 11 may extend. The clamping element 23 may be shaped, for example, long ring or consist of a ring nut.

Moreover, the clamping element 23 may be configured to impart, by means of said abutment element 13 and said spacer 22, a preload to the stress detector 31.

The clamping element 23 by means of said abutment element 13 and said spacer 22 may exert a force or thrust on the stress detector 31 even when the welding assembly 10 is not powered. Preferably, the stress detector 31 is calibrated to not detect said preload, alternatively said stress detector 31 is configured to not deduct said preload from the measured value of said stress. Preferably, the welding assembly 10 and the support assembly 20 are part of a manual unit 50.

Said manual unit 50 may comprise a first part 51 equipped with a welding assembly 10 and a support assembly 20, and a second part 52 connected to said first part 51 in such a way as to support it and equipped with an ergonomic part which can be gripped by an operator.

In particular, said second part 51 may be connected to the support assembly in a removable fashion by means of a connecting element 53. Said connecting element 53 may be configured to make a reversible coupling, such as screw or snap-on, with a proximal portion 25 of the second support assembly 20.

Said proximal portion 25 is defined by the opposite side of the support assembly 20 with respect to the seat 21 along said first direction of extension A. The first part 51 of the manual unit 50 may extend along a first direction of extension A and the second portion 52 may extend along a second direction of extension B. The second part 52 will preferably be movable relative to the first part 51 to move from a first configuration to a second configuration and vice versa where: - the first configuration has the second direction of extension B askew, with respect to the first direction of extension A and, preferably, inclined with respect to the latter by an angle preferably between 30° and 75° and more preferably between 45° and 60°, to give a pistol structure to the manual unit 50;

- the second configuration having the second direction of extension B substantially parallel to the first direction of extension A to give a straight or rectilinear structure to the manual unit 50. Advantageously, the second part 51 may be rotatable with respect to the first part 51, to move from the first configuration to the second configuration or vice versa. It may be understood, therefore, how a welding machine according to the invention can also be particularly flexible to use allowing the shape of the manual unit to be reconfigured in order to better adapt it to the most disparate processes.

It has therefore been found that the invention achieves the set aims and objectives, in particular allowing the quality and homogeneity of a weld to be improved by preventing the weld when the stress exerted by the operator is insufficient to ensure a good quality weld or if it is such as to damage the piece or compromise its shape.

The invention as it is conceived is susceptible to numerous modifications and variants, all falling within the scope of protection of the appended claims.

Further, all the details can be replaced by other technically-equivalent elements. In practice, the materials used, as well as the contingent forms and dimensions, can be varied according to the contingent requirements and the state of the art. Where the constructional characteristics and the technical characteristics mentioned in the following claims are followed by signs or reference numerals, the signs or reference numerals have been used only with the aim of increasing the intelligibility of the claims themselves and, consequently, they do not constitute in any way a limitation to the interpretation of each identified element, purely by way of example, by the signs or reference numerals.

Claims

1. Manual or automatic welder (100) comprising:

- a welding assembly (10) configured to be placed in contact with a piece to be welded and operable to ultrasonically weld a piece with which it is placed in contact;

- a support assembly (20) to which the welding assembly (10) is connected to support the latter;

- a control assembly (30) connected to the welding assembly (10) and to the support assembly (20) and configured to detect a stress exerted between the welding assembly (10) and the support assembly (20); wherein the control assembly (30) is further configured or programmed to inhibit the activation of said welding assembly (10) and/or deactivate said welding assembly (10) if said stress does not satisfy a predefined condition; wherein said predefined condition is satisfied if said stress is comprised between a lower threshold and an upper threshold or if it is less than an upper threshold.

2. Welder (100) according to claim 1, wherein the control assembly (30) is configured or programmed to deactivate said welding assembly (10) only if said stress does not satisfy said predefined condition continuously for a first period of time.

3. Welder (100) according to claim 2, wherein the control assembly (30) is configured to emit an alarm signal in the case wherein said stress does not satisfy said predefined condition continuously for a second pre-set time period which is shorter than said first time period, to signal to the operator the imminent deactivation of the welding assembly (10).

4. Welder (100) according to claim 3, wherein the control assembly (30) is configured or programmed in such a way that a difference between said first period of time and said second period of time consists in a period of time at least equal to 3 seconds and preferably at least 5 seconds.

5. Welder (100) according to one of the previous claims, wherein said control assembly (30) comprises a stress detector (31) mechanically connected both to said welding assembly (10) and to said support assembly (20) for detecting a mechanical stress transmitted between said welding assembly (10) and said support assembly (20).

6. Welder (100) according to claim 5, wherein said stress detector (31) is a force transducer or a pressure transducer.

7. Welder (100) according to claim 5 or 6, comprising a generator assembly (40) connected to said welding assembly (10) for feeding said welding assembly (10), and wherein said control assembly (30) comprises a control assembly (32) connected to said stress detector (31) and configured to control said generator assembly (40) to deactivate it or prevent its operation according to a stress signal received from said stress detector (31).

8. Welder (100) according to one of claims from 3 to 7, wherein said support assembly (20) comprises a bottom wall (21a) and a spacer (22) which leans against the welding assembly (10), and wherein the stress detector (31) abuts said bottom wall (21a) and said spacer (22) to detect a stress tending to move said welding assembly (10) close to said bottom wall (21a).

9. Welder (100) according to claim 8, wherein said spacer (22) is made of a material apt to dampen vibrations.

10. Welder (100) according to claim 8 or 9, wherein: said welding assembly (10) mainly extends along a first development direction A between a front region (10b), apt in use to be placed in contact with a piece to be welded, and a bottom region (10a) and comprises an abutment element (13), placed between said bottom region (10a) and said front region (10b), which extends in a plane (a) incident to said first development direction (A); and wherein said spacer (22) is configured in a cup-shape and comprises a base wall (222) and a side wall (221) connected to each other, or mutually integral, so as to define a seat (223) apt to receive the bottom region (10a) of said welding assembly (10); and wherein said base wall (222) of said spacer (22) abuts said stress detector (31) and said side wall (221) abuts said abutment element (13).

11. Welder (100) according to claim 10, wherein said welding assembly (10) comprises:

- an ultrasound emitter (11) that can be fed at a predefined frequency to generate energy in form of vibration; and wherein said emitter (11) comprises a bottom region (112) which defines said bottom region (10a), and a coupling region (111) opposite to said bottom region (112); - a sonotrode (12) that can be removably coupled to the coupling region of the emitter (111) to transmit, to a piece to be welded, energy received from the emitter (11 ) in form of vibration; wherein said sonotrode (12) comprises a frontal region (121), coinciding with the front region (10b) of the welding assembly (10), and a coupling region (122), opposite to the frontal region (121), apt to be coupled to said coupling region (111 ) of the emitter (11 ); and wherein said abutment element (13) is interposed between said bottom region (11 ) of the emitter (11 ) and said coupling region (111 ) of the emitter (11 ).

12. Welder (100) according to claim 11, wherein said support assembly (20) comprises a clamping element (23), configured to abut against said abutment element (13) of the emitter (11) on the opposite side with respect to the side wall (221) of the spacer (22) in said first development direction (A); and wherein said clamping element (23) is configured to ensure a mechanical connection between the spacer (22) and the stress detector (31 ). 13. Welder (100) according to claim 12, wherein said clamping element

(23) is configured to give, through said abutment element (13) and said spacer (22), a preload to the stress detector (31 ).