JP2015047629A - Anvil for ultrasonic welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anvil for an automatic welding machine in which there is limitation to an anvil, a weight and a size of an anvil holder, the anvil allowing collision between vibration of the anvil and vibration of a hone through a workpiece to be prevented.SOLUTION: An anvil has a slit 7 formed of: a vertical slit 5 extending toward a part beneath a welding protrusion part 3 of an anvil body 2 from a center of the welding protrusion part 3 up to a substantially central part of the anvil body 2; and a lateral slit 6 orthogonal to the vertical slit in a crossing state in the vicinity of a lower end of the vertical slit 5. Thereby the welding protrusion 3 and its lower side part are bent in a direction substantially parallel to a vibration vector of a hone.

Description

  The present invention relates to an anvil for ultrasonic welding.

  The principle of ultrasonic plastic film welding is that a plurality of plastic films are sandwiched between an ultrasonically vibrating horn and a fixed anvil, and pressure is applied between the plastic films caused by ultrasonic vibration generated by the horn. This is because frictional heat and strain stress applied to the plastic film cause frictional heat between molecular chains and melt.

  Generally, the vibration frequency of the horn is 20 kHz to 80 kHz, and the amplitude is 50 μm to 5 μm. Further, when the plastic film is thick according to the thickness of the plastic film, the welding strength can be increased in proportion to the pressure and amplitude.

  Thus, when ultrasonically welding one ultrathin plastic film having a thickness of 50 μm or less, the vibration of the horn penetrates the work and induces the vibration of the anvil. Further, as the amplitude of the horn increases and time elapses, distortion occurs in the vibration of the anvil, and as a result, the vibration of the anvil and the vibration of the horn cause a collision through the workpiece. This causes a rampage of the horn and anvil, leading to unstable welding. In some cases, the converter may be damaged.

  FIGS. 15 to 19 show a vibration relationship with a conventional anvil and horn, in which 100 is an anvil. The anvil 100 is provided with a welding projection 102 on the top of the main body 101, and a protrusion 103 is formed on the upper surface of the welding projection 102. Reference numeral 104 denotes a horn.

  Thus, when an ultra-thin plastic film (not shown) having a thickness of 50 μm or less is ultrasonically welded between the anvil 100 and the horn 104, as shown in FIG. The vibration of the horn 104 induces the vibration of the anvil 100 through the workpiece. In FIG. 17, A indicates vibration at the tip A portion of the horn 104 in FIG. 16, and B indicates vibration at the upper end B portion of the anvil 100 in FIG.

  As the amplitude of the horn 104 increases and time elapses, distortion occurs in the vibration of the anvil 100 as shown in FIG. 17 and FIG. 18 and FIG. Then, as shown in FIG. 19, the vibration of the anvil 100 and the vibration of the horn 104 cause a collision at a location indicated by S through the workpiece.

  By the way, the induction of vibration of the anvil due to the vibration of the horn as described above is suppressed by increasing the weight and size of the anvil and the anvil holder as in a normal ultrasonic welding machine. However, it is difficult to handle when there are restrictions on the weight and size of an anvil and anvil holder such as an automatic welding machine.

  In view of this, the present inventor has intensively studied on the suppression of the generation of vibration distortion when the anvil such as an automatic welding machine, which has restrictions on the weight and size of the anvil and the anvil holder, is induced by the vibration of the horn.

And in the research on this point, the theory of anti-vibration design was referred to when considering the vibration behavior of ultrasonic horn and anvil. If the damping ratio is ignored in the elastic support design of the machine, the effect of the anti-vibration design can be evaluated by the vibration transmissibility representing the ratio of the force acting on the machine and the force transmitted to the ground. According to the theory of anti-vibration design, when the vibration frequency of the machine is f and the natural frequency on the ground side is f ₀ , the vibration transmissibility is in the region where the frequency ratio f / f ₀ is greater than √2. It becomes smaller than 1 and has an anti-vibration effect. Here, the vibration frequency of the machine can be regarded as the frequency of the ultrasonic horn, and the natural frequency on the ground side can be regarded as the natural frequency of the anvil. In general, f / f ₀ may be estimated from √2 to √5 (with an ultrasonic frequency of 40 kHz, the anvil frequency is 20 kHz to 8 kHz). If there are no particular restrictions on the anvil side, it is not necessary to be aware of the anti-vibration design if the anvil and anvil holder are constructed with a certain weight and size.

  However, when there are restrictions on the weight and size of the anvil and anvil holder as in an automatic welding machine, vibration prevention cannot be realized unless the above-mentioned theory of vibration isolation design is actively incorporated. However, it is not easy to realize the theory of anti-vibration design under the constraints of weight and size. For example, if the same axial resonance as that of the horn is used, even if it is a half-wave resonator, a size twice as long as the length of the horn is required if a half frequency is aimed. In addition, it is difficult to implement vibration-proof design by adopting vibration-proof rubber that aims at several hertz to several tens of hertz as in ordinary machine products due to large differences in elastic modulus and frequency.

  Therefore, the present inventor further researched and provided a slit and / or cavity having a predetermined shape directly below the welding projection in the anvil body, and the welding projection and its lower part were substantially parallel to the vibration vector of the horn. It has been found that bending vibration is generated in the welding projection and the lower portion of the anvil body during welding, and no distortion occurs in the vibration by allowing the bending in the direction. And this enables the anvil and anvil holder to realize the theory of anti-vibration design even when its weight and size are small due to constraints, and the vibration of the anvil and the vibration of the horn cause a collision through the workpiece. It has come to see the realization of an ultrasonic welding anvil that can be avoided.

  Thus, the gist of the present invention is that a slit and / or cavity having a predetermined shape is provided immediately below the welding projection in the anvil body, and the welding projection and its lower part are the vibration vector of the horn. An ultrasonic welding anvil characterized by being able to bend in a substantially parallel direction.

  Further, in the above configuration, the slit includes a vertical slit extending directly below from the center of the welding projection to a substantially central portion of the anvil body, and a horizontal slit orthogonal to the cross in the vicinity of the lower end of the vertical slit. It may be a slit.

  Moreover, the said structure WHEREIN: The circular cavity provided in the approximate center part of the anvil main body just under the said welding projection part may be sufficient.

  Further, in the above configuration, the slit and the cavity are a circular cavity provided at a substantially central portion of the anvil body directly below the welding projection, and a vertical slit extending from the center of the welding projection to the circular cavity. And a horizontal slit extending left and right from the circular cavity.

  Further, in the above-described configuration, the slit and the cavity are provided at a substantially central portion of the anvil body directly below the welding projection, and have a substantially triangular cavity having a slight vertical portion from the left and right sides to the oblique side of the base, and the welding It may be a vertical slit extending directly from the center of the protrusion to the substantially triangular cavity.

  The present invention is configured as described above, and a slit and / or cavity having a predetermined shape is provided directly below the welding projection in the anvil body, and the welding projection and its lower part are substantially parallel to the vibration vector of the horn. Since it can bend in the direction, bending vibration is generated in the welding projection and its lower portion of the anvil body being welded, so that no distortion is generated in the vibration. Therefore, even if the anvil and anvil holder of an automatic welding machine are limited and their weight and size are small, the theory of vibration isolation design can be realized, and the vibration of the anvil and the vibration of the horn It is possible to prevent a collision from occurring. Therefore, the horn and the anvil are not ramped, and the welding is not unstable. In addition, the converter is not damaged.

1 is a perspective view of an ultrasonic welding anvil according to a first embodiment of the present invention. It is a coaxial sectional view. It is sectional drawing of the state at the time of welding which abbreviate | omitted and showed the workpiece | work. It is a partial expanded sectional view of the state at the time of the welding. It is a figure which shows the vibration vector which represented the vibration direction and magnitude | size at the time of the same welding with the one way arrow. It is a vibration state figure of the tip part of a horn and the upper end part of an anvil at the time of the welding. FIG. 7 is a partially enlarged view of the first half portion of oscillation in FIG. 6. FIG. 7 is a partially enlarged view of the latter half of the oscillation in FIG. 6. It is an axial sectional view of an ultrasonic welding anvil concerning a 2nd embodiment of the present invention. It is a figure which shows the vibration vector which represented the vibration direction and magnitude | size at the time of the same welding with the one way arrow. It is an axial sectional view of an ultrasonic welding anvil concerning a 3rd embodiment of the present invention. It is a figure which shows the vibration vector which represented the vibration direction and magnitude | size at the time of the same welding with the one way arrow. It is an axial sectional view of an ultrasonic welding anvil concerning a 4th embodiment of the present invention. It is a figure which shows the vibration vector which represented the vibration direction and magnitude | size at the time of the same welding with the one way arrow. It is a perspective view of the conventional ultrasonic welding anvil. It is sectional drawing of the state at the time of welding which abbreviate | omitted and showed the workpiece | work. It is a vibration state figure of the tip part of a horn and the upper end part of an anvil at the time of the welding. FIG. 18 is a partially enlarged view of the first half portion of oscillation in FIG. 17. FIG. 18 is a partially enlarged view of the latter half of the oscillation in FIG. 17.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  In the figure, reference numeral 1 denotes an anvil, and the anvil 1 is an anvil in an automatic welding machine or the like having restrictions on the weight and size of the anvil and anvil holder.

  The anvil 1 is provided with a welding projection 3 on the top of the main body 2, and a protrusion 4 is formed on the upper surface of the welding projection 3. The anvil 1 includes a vertical slit 5 extending directly below the welding projection 3 in the main body 2 from the center of the welding projection 3 to a substantially central portion of the anvil main body 2, and a vicinity of the lower end of the vertical slit 5. In FIG. 2, a slit 7 comprising a cross slit 6 and a transverse slit 6 is provided so that the weld projection 3 and its lower part can be bent in a direction substantially parallel to the vibration vector of the horn. In the figure, reference numeral 8 denotes a horn, and W denotes a workpiece made of ultra-thin plastic films 9 and 10 each having a thickness of 50 μm or less, which are stacked for welding.

  According to this embodiment, the bending vibration as shown in FIG. 5 is generated in the welding projection 3 and the lower portion of the anvil body 2 during welding. As a result, as shown in FIGS. 6 to 8, no distortion occurs in the vibration of the portion of the anvil 1. Therefore, in the anvil 1 in an automatic welding machine or the like having restrictions on the weight and size of the anvil and the anvil holder, the vibration of the anvil 1 and the vibration of the horn 8 do not collide through the workpiece W. FIG. 5 shows the vibration in one direction, but it actually reciprocates. In FIGS. 6 to 8, A is the vibration at the tip A portion of the horn 7 in FIG. 3, and B is in FIG. The vibration in the upper end B part of the anvil 1 is shown.

  Next, a second embodiment of the present invention shown in FIGS. 9 and 10 will be described.

  The present embodiment and the first embodiment are that a cavity is used in this embodiment instead of the slit in the first embodiment.

  That is, in the present embodiment, a circular cavity 11 is provided at a substantially central portion of the anvil body 2 just below the welding projection 3 in the anvil body 2. As a result, the welding projection 3 and its lower portion can be bent in a direction substantially parallel to the vibration vector of the horn 8. Therefore, flexural vibration as shown in FIG. 10 is generated, and distortion is not generated in the vibration of the welding projection 3 of the anvil 1 and its lower portion as in the first embodiment.

  Next, a third embodiment of the present invention shown in FIGS. 11 and 12 will be described.

  This embodiment is different from the first embodiment in that the slit in the first embodiment and the cavity in the second embodiment are combined in the present embodiment.

  That is, in the present embodiment, a circular cavity 12 provided in a substantially central portion of the anvil body 2 immediately below the welding projection 3 and a center of the welding projection 3 are provided directly below the welding projection 3 in the anvil body 2. A vertical slit 13 extending right below from the circular cavity 12 and lateral slits 14 and 15 extending left and right from the circular cavity 12 are provided. As a result, the welding projection 3 and its lower portion can be bent in a direction substantially parallel to the vibration vector of the horn 8. Therefore, flexural vibration as shown in FIG. 12 is generated, and no distortion occurs in the vibration of the welding projection 3 of the anvil 1 and its lower portion as in the first embodiment.

  Next, a fourth embodiment of the present invention shown in FIGS. 13 and 14 will be described.

  This embodiment is different from the first embodiment in that the slit in the first embodiment and the cavity in the second embodiment are combined in the present embodiment.

  That is, this embodiment has a slight vertical portion from the right and left of the bottom side to the oblique side, which is provided at a substantially central portion of the anvil body 2 just below the welding projection 3 just below the welding projection 3 in the anvil body 2. A substantially triangular cavity 16 and a vertical slit 17 extending directly from the center of the welding projection 3 to the substantially triangular cavity 16 are provided. As a result, the welding projection 3 and its lower portion can be bent in a direction substantially parallel to the vibration vector of the horn 8. Accordingly, flexural vibration as shown in FIG. 14 occurs, and no distortion occurs in the vibration of the welding projection 3 of the anvil 1 and its lower portion as in the first embodiment.

DESCRIPTION OF SYMBOLS 1 Anvil 2 Anvil main body 3 Welding protrusion 4 Projection 5 Vertical slit 6 Horizontal slit 7 Slit 11 Circular cavity 12 Circular cavity 13 Vertical slit 14, 15 Horizontal slit 16 Substantially triangular cavity 17 Vertical slit

Claims (5)

  A slit and / or cavity having a predetermined shape is provided immediately below the welding projection in the anvil body, and the welding projection and its lower part can be bent in a direction substantially parallel to the vibration vector of the horn. Characteristic ultrasonic welding anvil.   The slit is a slit comprising a vertical slit extending directly from the center of the welding projection to a substantially central portion of the anvil body, and a horizontal slit orthogonal to the cross in the vicinity of the lower end of the vertical slit. An ultrasonic welding anvil as described.   2. The ultrasonic welding anvil according to claim 1, wherein the cavity is a circular cavity provided in a substantially central portion of the anvil body directly below the welding projection.   A circular cavity provided at a substantially central portion of the anvil body directly below the welding projection, a vertical slit extending from the center of the welding projection to the circular cavity, and the circular cavity. The ultrasonic welding anvil according to claim 1, wherein the anvil is a horizontal slit extending from side to side. The slit and the cavity are provided at a substantially central portion of the anvil body directly below the welding projection, and have a substantially triangular cavity having a slight vertical portion from the left and right sides to the hypotenuse, and the center of the welding projection. The ultrasonic welding anvil according to claim 1, wherein the anvil is a vertical slit extending directly down to a substantially triangular cavity.

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