JPS633791Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to the structure of a plastic container in which a main body and a bottom are formed separately and are integrally formed by welding.

In recent years, plastic soy sauce containers, seasoning containers, etc. have been widely used because of their low manufacturing costs, aesthetic appeal, and ease of use. These products often have a design with a bulge at the bottom of the outer wall to give them a sense of stability so that they do not fall over during use, or to give them a sense of richness and softness. To form one piece, a split mold was used for the outer shape, but for the inner shape, the core used was pulled out upward as shown by the arrow in Figure 1, so the lower part of the main body 1 had a bulge. In the case of transparent or semi-transparent colored products, the thick part produces a lens effect, but only partially. Sink marks or flow marks may occur, or the degree of refraction of light may differ.
It was unavoidable that the resin would have a flow pattern, resulting in a partial appearance defect.

In order to eliminate this drawback, the container is separated into two parts, a cylindrical body 1 with a widened bottom and approximately equal thickness, and a bottom part 2 welded to the bottom of the body, as shown in Figure 2. Conventionally, a method has been adopted in which the parts are molded separately and then welded together. In this method, as shown in FIGS. 3 and 4, a step 4 with a cylindrical surface 3 is formed at the lower end of the main body 1 between the outer peripheral surface and the inner peripheral surface, and also at the upper end of the outer edge of the bottom part 2. A step part 6 having an inner cylindrical surface 5 is formed between the outer peripheral surface and the inner peripheral surface corresponding to the lower end of the main body, and a step part 6 having an inner cylindrical surface 5 inside the cylindrical surface is formed on either the opposing surface of the main body 1 and the bottom part 2 in the vertical direction. An annular welding rib 7 extending in the welding rib 7 was formed and welding was performed at the welding rib portion using ultrasonic waves. In this case, the welding rib 7 is provided on the inside in order to obtain sufficient watertightness or sufficient bonding strength between the main body and the bottom, but if the main body and the bottom are made thick, dimensional variations in the product after molding can be avoided. Therefore, the product value is often damaged due to poor assembly of the main body and the bottom, or gaps or protrusions in the joining line 8 that appear at easily visible locations on the outer circumferential surface. Furthermore, JP-A-49-17861 discloses a technique for welding a stepped joint on all end faces, but since there is no gap at all in the welded part on the vertical plane, the welded part always has a direction toward the outer circumference. During actual use, there is a problem that the strength of the welded part decreases due to impact force and repeated drying and wetting.

This invention aims to solve these conventional problems.It is possible to perform ultrasonic welding even if the main body and bottom part are thick, and the inner cylinder of the main body can be welded without reducing the strength of the welded part. This invention relates to a plastic container in which the cylindrical surface and the bottom cylindrical surface are welded with a small gap left between them.

Next, an embodiment of this invention will be described with reference to the drawings. FIG. 5 shows an example of a soy sauce jug, in which the body of the container is molded into two parts, a main body 11 and a bottom part 12. As is clear from the enlarged views of FIGS. 6 and 7, the lower end of the outer circumferential surface 13 of the main body 11 forms a sloped surface 14 that becomes smaller in diameter as it goes downward. The sloped surface 14 is usually a spherical surface, but may also be a conical surface. The outer circumferential surface 13 of the main body 11 continues to the bottom surface 15 via a sloped surface 14. Main body 1
1 has a substantially constant wall thickness and bulges at the bottom, so that the core can be extracted downward during molding. However, the main body and the bottom may be thick, or the lower part of the main body may have a partially thick wall in the shape of a lens. The inner circumferential surface 16 of the main body 11 has a stepped portion 1 extending in the outer circumferential direction at a position close to the bottom surface 15.
7 is provided, the step 17 adjoining at its outer end an inner cylindrical surface 18 adjoining the bottom surface 15 . On the other hand, the bottom portion 12 is approximately disk-shaped, and its outer peripheral surface is a cylindrical surface 19. The cylindrical surface 19 has a smaller diameter than the inner cylindrical surface 18 of the main body 11, and a small gap d is provided therebetween as shown in FIG.

The outer peripheral edge of the upper surface of the bottom portion 12 forms a surface 20 parallel to the stepped portion 17 of the main body, and is provided with an annular welding rib 21 projecting upward. Welding rib 21
If a slightly lower step is provided on the inner circumferential surface side as shown in FIG. 6, the protrusion of the inner circumferential surface at the joining line can be reduced. A collar 22 is provided at the lower part of the bottom portion 12 and protrudes from the lower end of the cylindrical surface 19 in the outer circumferential direction. This flange 22 is thin and has an upper surface parallel to the bottom surface 15 of the main body, and an annular welding rib 23 is also provided on the upper surface of the flange 22. These welding ribs 21 and 23 may be provided on opposing surfaces of the main body 11 instead of being provided on the bottom. The height of the cylindrical surface 19 of the bottom portion 12 is approximately equal to the height of the inner cylindrical surface 18 of the main body 11.

A bottom portion 12 is attached to the main body 11 having the above structure.
When the welding ribs are welded by inserting them almost concentrically and applying ultrasonic waves, the cylindrical surface 1 is formed as shown in Fig. 7.
9 and the inner cylindrical surface 18 are not welded, but the main body 1
The step portion 17 and the bottom surface 15 of No. 1 are welded together. The welded portion on the upper surface of the bottom portion welded by the welding ribs 17 is where the main bonding force between the main body and the bottom portion is generated, and this portion serves as the main welded portion and has sufficient watertightness. Since the joining line 24 in this part is on the inner surface, even if it protrudes, it will not damage the appearance, and if necessary, the protrusion can be reduced by providing a step as described above on the inside of the welding rib. It is possible.

The welding rib 23 between the flange 22 and the bottom surface 15 is not necessarily necessary, but if it is provided and this part is welded, soy sauce may come out from the bottom into the gap due to capillary action, or dirt may enter the gap. This will prevent it from getting in and not coming off even after washing. However, the joining line 25 of this part is
1 is formed at the lower end of the sloped surface 14 at the bottom of the main body and serves as an auxiliary welding part, and the joining line 25 between the main body and the bottom part is located at a position that cannot be visually seen from the outside. In addition, since the flange 22 is thin, it cannot be seen from the outside when the product is left standing, so even if the gap gets a little dirty or there is protrusion due to welding, there is no risk of damaging the appearance. . In addition, the inner cylindrical surface 18
A gap d is provided in advance between the cylindrical surface 19 and the cylindrical surface 19 to prevent welding at this portion. The reason for providing such a gap is that if there were no gap, when ultrasonic welding was performed, stress would always be applied to the inner cylindrical surface 18 of the container body in the outer circumferential direction, that is, the diameter of the container body would expand. This is because the impact force during use of the container and repeated drying and wetting in the usage environment can cause crazing or, in extreme cases, cracks in the main body, so it is necessary to provide a gap d. This is because the residual internal stress after welding is reduced, making it possible to obtain an injection molded plastic container that can withstand long-term use and has sufficient bonding strength at the welded portion. In addition, there is a hole for insertion at the bottom of the main body,
In other words, if the diameters of the inner cylindrical surface 18 and the cylindrical surface 19, which is the outer peripheral wall of the bottom part, are thick, the molding conditions will vary and the diameters will not be constant, making assembly difficult especially if the inner cylindrical surface 18 of the main body has large variations. This is to prevent it from becoming.

In another embodiment shown in FIG. 8, the lower end of the outer circumferential surface 13 is not provided with the sloped surface 14, but is connected to the bottom surface 15 via a rounded portion of approximately a chamfer, and the flange 22 of the bottom surface 12 is connected to the bottom surface 15 at the lower end of the outer circumferential surface. The diameter is smaller than the diameter D, and since the joining line between the bottom surface 15 and the collar appears on the bottom surface 15, it cannot be easily seen. It should be noted that parts equivalent to those in the previous embodiment are given the same reference numerals.

Further, in other embodiments shown in FIGS. 9 to 11, a chamfered portion 26 for welding is provided near the base of the flange 22 without providing an annular welding rib 23 on the upper surface of the flange 22. A joining line 25 between the bottom surface 15 of the main body 11 and the collar 22 appears on the bottom surface 15 and cannot be easily seen. Compared to the case where welding is performed with welding ribs 23 provided, the protrusion that occurs at the joining line 25 tends to be less, and there is also a tendency for welding failures that occur due to unstable molding factors such as deformation and sink marks due to the thick body and bottom parts. There is also a tendency to decrease.

As described above, according to this invention, the inner cylindrical surface 18 of the main body and the bottom cylindrical surface 19 are welded with a small gap d left in the vertical direction, so that the inner cylindrical surface 18 of the main body and the bottom cylindrical surface 19 are welded with a small gap d left in the vertical direction. This has the great advantage of preventing the generation of residual internal stress and obtaining a welded part with sufficient bonding strength, watertightness, and durability without reducing the strength near the welded part, increasing the commercial value.
Even if the main body is thick, conventionally it was difficult to avoid internal stress concentration in the relatively thin parts caused by providing a stepped part on the main body, resulting in an unavoidable decrease in strength. This problem could be easily solved by providing a small vertical clearance d.
Furthermore, the welding part of this invention is double-layered, consisting of a main welding part by the joining line 24 formed at the step part 17 of the main body, and an auxiliary welding part by the joining line 25 between the bottom surface 15 of the main body and the bottom flange 22. Since it is welded to the main body, the joint strength is further improved, watertightness is increased, and the base of the stepped part 17 of the main body is prevented from weakening and being damaged due to the intrusion of heat or chemicals from the outside. It can produce excellent effects.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional view of the main part of a conventional plastic container, Fig. 2 is a longitudinal sectional view of the main part of another conventional plastic container, and Fig. 3 is an enlarged view of section A in Fig. 2, showing the welded part. The state before welding is shown, and Figure 4 is also A.
Fig. 5 is a longitudinal sectional view of the embodiment of this invention, Fig. 6 is an enlarged view of part B in Fig. 5, showing the state before welding, and Fig. 7 shows the state after welding. 8 is an enlarged view of part B and shows the state after welding, and FIG. 8 is an enlarged view of part B corresponding to FIG. 7 of another embodiment, and FIG.
The figure is an enlarged view of the welded part corresponding to Figure 6 of another embodiment, showing the state before welding, and Figure 10 is C of Figure 9.
FIG. 11 is an enlarged sectional view showing the state of part C after welding. DESCRIPTION OF SYMBOLS 11... Main body, 12... Bottom, 13... Outer circumferential surface, 14... Gradient surface, 15... Bottom surface, 16... Inner circumferential surface, 17... Step part, 18... Inner cylindrical surface, 19...
Cylindrical surface, 20... surface, 21... welding rib, 22...
...Tsuba, 24...Joining line, d...Gap.

Claims (1)

[Scope of utility model registration request] In a plastic container whose bottom part is ultrasonically welded to the lower end of a cylindrical container main body, there is a stepped part extending in the outer circumferential direction at a position close to the bottom surface of the inner circumferential surface of the main body, and an inner cylindrical shape that reaches from the end of the stepped part to the bottom surface. The bottom has an outer periphery that is approximately equal in height to the inner cylindrical surface and has a slightly smaller diameter with a gap, and the outer periphery of the upper surface of the bottom has a cylindrical surface that is approximately the same height as the inner cylindrical surface and has a slightly smaller diameter. Parallel surfaces are provided, and a flange is provided that extends in the outer circumferential direction from the lower end of the cylindrical surface and is substantially parallel to the bottom surface of the main body, and an annular welding rib is provided on either the step portion of the main body or the upper surface of the bottom portion opposite thereto. The welding rib portion is ultrasonically welded to form the main welding part, and the collar is ultrasonically welded to the bottom surface of the main body to form the auxiliary welding part, and the inner cylindrical surface of the main body and the bottom cylindrical surface are An injection molded plastic container characterized by a small gap formed between the containers.