JPS6210094Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a sealing mechanism in a tube sealing machine, particularly in a sealing machine for plastic tubes.

Plastic tubes, which are currently widely used for storing various paste-like articles, are melt-sealed using ultrasonic waves, high frequencies, heat, etc., taking advantage of the possibility of welding by heat. These sealing operations are generally performed by pinching the tube with a pair of bits with narrow tips that correspond to the seal line of the tube to be treated, but plastics are generally thermally conductive. Moreover, since only the narrow seal line is heated, the material other than the crimped part still remains flexible, so it is necessary to always apply this to the welded part to be closed. A force that pushes and expands works. As expected, this phenomenon becomes more severe as the tube becomes thicker and the material of the tube becomes harder. The same applies when the diameter of the tube is small and the length of the welding line is short. When this phenomenon occurs, the seal becomes incomplete and peels off at that portion, resulting in defects such as pinholes.

One solution to the above problem is to maintain the clamping until the bits have cooled sufficiently. However, if this is done, the cycle for each sealing step will of course become longer, which inevitably leads to a decrease in productivity. Another solution is to heat and press the area to be sealed in advance to flatten it into an oval shape, but this requires separate equipment and may not be applicable depending on the type of content. occurs. The present invention relates to a means for easily solving the above-mentioned problems in known tube seal machines.
The basic idea is to attach a pressing claw to the welding bit, and after the bit finishes welding to the claw and leaves the part to be welded (i.e., the crimping surface at the tip of the bit),
The aim is to keep it crimped near the part to be welded for a while.

Fig. 1 shows the principle of the above concept, in which a guide pin 2 along the longitudinal direction of the bit 1 is installed in the stepped portion 1b rearward from the tip 1a of the bit 1, and a pressing pin is attached to the pin 1. The pawl 4 is loosely fitted through a through hole 5 made in the upright portion (base) 4a at the rear thereof, and a coil spring 3 is fitted around the guide pin 2 to allow the pawl 4 to move forward of the bit 1. It is energized along the direction (arrow). seal bed 6
are arranged oppositely from the tip surface 1a of the bit at a slight distance, and as shown in the figure, the welded part S of the tube T to be welded is sandwiched between the surface 1a and the tip 6a of the bed, and at this time ultrasonic waves are applied. , the relevant portion S of the tube T is welded by high frequency, heat, or other energy (A in the same figure). When the welding is completed, the bit 1 moves back, but at this time, the spring 3 applies thrust to the claw 4, so even if the bit 1 leaves the part to be welded, the tip 4a of the claw 4 remains in the bed 6 for a while. Press the lower part of the welded part (in the drawing) against
Therefore, the sandwiched state is maintained until the part to be welded solidifies, so that peeling does not occur at the part. Furthermore, if the pawl 4 is made of a heat-conducting material, heat is radiated through the pawl as well, so the reliability of welding is further improved (FIG. B).

In the above, there is no particular need to rely on springs for the thrust against the pressing claws, and pure mechanical means using fluid pressure such as hydraulic pressure, air pressure, cams, etc. can be freely adopted, but the anti-compression force of the springs can be used. This is the simplest method. Furthermore, although the claws may be provided on both the upper and lower surfaces of the bit (in the drawings), in reality, it is sufficient that the claws be provided only on the lower surface of the bit, that is, below the weld line (on the opposite side from the open end of the tube to be sealed). It is.

As a result of various experiments, the present inventor found that by making a slight incision in the part of the bed 6 that faces the tip 4a of the claw, the bit 1 and the bed 6 can be joined together at the welded part S of the tube T, as shown in Fig. 2. Since the pressed resin material escapes to the notch 6b and the contact area of the claw, a built-up part S' is formed below the welded part S, which improves the appearance of the welded part and also improves the appearance of the welded part. It has been discovered that defects such as pinholes can be avoided by strengthening the boundary between the seal and the non-sealed part. The appropriate depth d of this notch 6b varies somewhat depending on factors such as the thickness of the tube used and the degree of pressure for welding (in other words, the minimum clearance between surfaces 1a and 1b), so in reality It is preferable to design the notch so that the depth of the notch can be adjusted. The specific value is 0.05mm
~0.2mm.

The welding energy of the tube sealing machine, which is the subject of the present invention, can be supplied by known means such as ultrasonic vibration, high frequency, heat conduction unit heat, etc. Among these, high frequency energy is used for polyvinyl chloride,
It can be used for resin materials with a high dielectric power factor, such as ABS, polyamide, and cellulose acetate, but cannot be used for polyolefin resins, polyacetal, polystyrene, etc., which have a low power factor. On the contrary, ultrasonic vibration and Joule heat can be applied regardless of the type of material. However, in order to use Joule heat, it is necessary to heat the bit itself, and in this case, there is a large time lag between when the electricity is turned off and when the temperature at the tip of the bit falls to an appropriate level. Even if this method is used, it is unsuitable for the purpose of high-speed welding. On the other hand, the vibration heat produced by ultrasonic waves can be controlled electrically, and the generation of heat immediately stops when the power is turned off, so this, combined with the aforementioned versatility, is the most advantageous for the purpose of the invention.

In the explanation of Fig. 1 above, the pawl was explained as being loosely attached to the rear of the bit for convenience, but with this method, it is inevitable that vibrations will be transmitted to the pawl.
Therefore, not only the efficiency of energy transmission to the tip of the bit, which is important, decreases, but also undesirable phenomena such as the generation of noise due to resonance are likely to occur. For this reason, it is actually desirable to completely separate the bit and the claw so that although they move simultaneously, they are mechanically insulated. As is clear from the above description, either or both of the bit (and pawl) and the bed may move toward the tube to be sealed and pinch the part to be welded. Although the bed side can also be replaced with bits (that is, bits can be sandwiched from both sides), it is usually sufficient to provide bits only on one side.

The mode of implementing the invention will be described below with respect to one typical example of the invention, but this is of course an illustration and is not intended to limit the technical scope of the invention.

FIG. 3 is a schematic perspective view showing the main parts of a sealing machine including the welding assisting mechanism of the present invention, and FIG. 4 is a side view of the same.

The ultrasonic bit 1 moves forward and backward toward the bed 6 together with the support frame 7 repeatedly. A pair of guide pins (2, 2; however, only one side is shown) is implanted in the lower horizontal frame 7a of the support frame 7, and in front of the pins is an L-shaped cross section made of a metal with good thermal conductivity. Pressing claw 4
is fitted loosely through a through hole 5 bored in its base, and a coil spring 3 is inserted between it and the horizontal frame 7a, and the tip 4a of the claw 4 is energized by this spring 3. When the bit 1 is away from the seal bed 6, the tip 1a of the bit 1
protrude forward from.

The seal bed 6 is fixed at a position facing the bit 1, and on its lower surface (as shown in the figure) there is a slide metal fitting 6' with a slot 9 carved in the center at a position corresponding to the pawl 4 as shown in FIG. is fixed with bolts 8 so as to be adjustable. Distance d between the front end 6'a of this metal fitting 6' and the front end 6a of the bed 6
As mentioned above, is selected from an appropriate value within the range of approximately 0.05 to 0.2 mm.

Tip 1a of bit 1 and tip 6 of seal bed 6
Insert the tube T to be welded between the
When the bit 1 is moved forward, the seal portion S is pinched in the minute gap between the two, and at the same time, the portion generates heat due to the ultrasonic vibration of the bit 1. When the wall portions of the superimposed tubes T melt, the power supply to the magnetostrictive vibrator (not shown) connected to the cone at the rear of the horn 10 that continues behind the bit 1 is immediately cut off, and at the same time, the bit and The claws begin to retreat. However, the pawl is still pressed downwardly by the propulsive force of the spring 3, and during this time, it continuously presses S' directly below (inside) the line to be welded against the metal fitting 6', and at the same time presses the part S' directly below (inside) the line to be welded against the metal fitting 6'. Promote heat dissipation from the welded part S.

As a synergistic effect of the pressing action and the heat dissipation action of the claws, the temperature at the welded part S drops with a sharp temperature gradient, and during this temperature drop, the claws 4 ' (in the drawings), so there is no risk of the sealed portion peeling off even if the welding operation is repeated at a fast cycle. In addition, in the part S', on the one hand, due to the compressibility of the spring 3 and the existence of the gap d between the bed and the metal fitting, the resin material is compressed in the gap between the bit and the bed, and the resin material protrudes in the part S'. Since the wall thickness of the portion is increased, the occurrence of pinholes that tend to occur at the boundary between the welded portion and the non-welded portion is also prevented. As described above, according to the device according to the present invention, defects such as peeling of the welded part that tends to occur when welding plastic tubes and pinholes that tend to occur at the interface between the welded part and the non-welded part can be prevented with a simple configuration. It has great practical value.

[Brief explanation of the drawing]

Fig. 1 is a perspective view A and a side view B showing the principle of the proposed mechanism, and Fig. 2 is a typical structure of the proposed mechanism, which is the structure of the welded part of the tube formed by providing a notch in the seal bed part as well. FIG. 3 is a perspective view of essential parts of a sealing device embodying the proposed mechanism, and FIG. 4 is a side view of the device shown in FIG. 3. The meanings of the main symbols used in the diagram are as follows: - 1: Bit, 2: Guide pin for sliding claw, 3: Coil spring, 4: L-shaped claw for pushing, 5: Base of claw 4 through hole, 6: Seal bed, 6': Slide metal fitting, 7: Bit support frame, 8: Slide metal tightening bolt, 9: Slide metal slot, 10: Exponential horn, S: Welded part (wire ), S′: Welded part (line)
T: Plastic tube.

Claims (1)

[Claims for Utility Model Registration] (1) A claw that intersects with the crimp surface of the welding bit of the tube seal machine and can slide along the side parallel to the longitudinal direction of the surface, and By applying a thrust toward the tip of the bit, the tip of the claw comes into contact with the weld line of the tube to be welded and presses the tube for a while after welding is performed. A welding assist mechanism for tube seal machines. (2) The welding auxiliary mechanism according to registered claim (1), wherein the thrust force to the pressing claw is provided by a spring. (3) The welding auxiliary mechanism according to registered claim (1) or (2), in which the pressing claw contacts the inside of the welding line. (4) The welding auxiliary mechanism according to any one of registered claims (1) to (3), wherein the pressing claw is made of a thermally conductive material. (5) Registered claims Paragraphs (1) to 3, in which the seal bed facing the pressing claw is recessed from the bed surface.
The welding assist mechanism described in any of paragraph (4).