JPH087575Y2 - plastic case - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a plastic case formed by stacking and welding upper and lower half cases, and in particular, a plastic case that is relatively small and has a limited welding space. It is about.

(Prior Art) In recent years, a wide variety of products use plastic resins. And, as one form in which a desired part is housed in a box-shaped case, for example, a magnetic disk cartridge, a magneto-optical disk cartridge, a magnetic tape cassette such as a video tape cassette or an audio tape cassette, A recording medium such as a disk or a tape is accommodated and is relatively small, and its molding accuracy is required. There is a case in which a plastic case constituted by stacking upper and lower half cases is used as an enclosure.

In the magnetic tape cassette, for example, JP-A-47-37913, JP-A-54-98604, and JP-A-57-102085,
Japanese Patent Laid-Open No. 64-871 discloses a device for fastening the upper and lower half cases.

The method disclosed in Japanese Patent Laid-Open No. 47-37913 is a method in which a protrusion is provided on a part of the joint end face on either one of the upper and lower half cases, and the protrusion is melted and bonded by an ultrasonic welding machine. The above-mentioned JP-A-54-98604 and JP-A-57-102.
What is disclosed in Japanese Patent No. 085 is to form a convex portion on one side and a concave portion to be fitted to the convex portion on the other side at the joining portion of the upper and lower cassette halves, and fit the concave and convex portions to position the upper and lower half cases. After that, it is a type that is welded by ultrasonic welding. Further, the one disclosed in Japanese Utility Model Laid-Open No. 64-871 discloses a structure in which a concave-convex fitting portion is welded and then the portion is screwed.

As is well known, the ultrasonic welding machine applies ultrasonic vibration of about 20 kHz to 40 kHz while appropriately pressing the joint surfaces, and the strong frictional heat generated at this time melts and welds the synthetic resin.

(Problems to be solved by the invention) As described above, in this type of plastic case such as the magnetic tape cassette, the upper and lower half cases may be fixed by ultrasonic welding in terms of productivity. Although various proposals have been made and adopted, in the case of ultrasonic welding, the structures shown in FIGS. 8 and 9 have been adopted. In the case of FIG. 8, the projections 2a are formed on the end surfaces of the side walls of the upper and lower half cases 2 and 3, and the projections 2a are overlapped with the lower half case 3 to melt the projections 2a. While providing the upper half case 2 with the concave portion 27, a convex portion 28 having a diameter smaller than the opening diameter of the concave portion 27 is formed on the lower half case 3, and both concave and convex portions are fitted to each other to form a tip surface of the convex portion 28. A structure has been adopted in which the contact portion between 29 and the bottom surface of the recess 27 is welded.

In any of these structures, the fine plastic powder 70 is generated almost at the same time as the welding of the joint portion. This is shaving powder generated when the bonded portions vibrate and rub against each other, and is generated in the time of the preceding stage in a short time until the welding is completed. When dust such as the fine powder 70 remains in the case, for example, when the built-in case is a magnetic disk or a magnetic tape, the fine powder 70 adheres to the recording medium and drops. This is a cause of deterioration of recording / reproducing characteristics such as occurrence of out.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a plastic case configured to effectively remove the fine powder during welding even if the upper and lower half cases are fastened together by ultrasonic welding. Is.

(Means for Solving the Problem) The above-mentioned problem of the present invention relates to a plastic case which is constructed by superposing upper and lower half cases and fixing and welding them by applying ultrasonic vibration to the welded butting portions of the upper and lower half cases. And an inner space is formed inside the butted portion and has at least one air hole communicating with the inner space, and a plastic case characterized by being sucked and welded from the air hole during the welding. can do.

(Embodiment) Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic exploded perspective view of a magnetic tape cassette for a VHS (registered trademark) type VTR according to the present invention. FIGS. 2 to 4 are schematic sectional views of a welded portion, and FIGS. FIG. 4 is a cross-sectional view of an essential part of another embodiment of the present invention.

As is well known, the tape cassette for VTR shown in FIG.
The schematic structure is that the tape reel 25 around which the magnetic tape 26 is wound,
It is housed in a cassette case composed of an upper half case 2 and a lower half case 3, and a tape drawer opening in front of the cassette case is covered by a guard panel 22 (other components are omitted for convenience).

The upper half case 2 is a box body composed of front and rear side walls 12 and 13 and left and right side walls 14 and 14 which are erected on the periphery of a rectangular upper wall surface 18 having a window opening 15, and is integrally formed by injection molding or the like. At the same time, a transparent window member is welded to the window opening 15, and the tape reel is provided at the center of the upper wall surface inside.
A leaf spring that urges 25 toward the bottom of the cassette is fixed.

The lower half case 3 is a box body including front and rear side walls 12 and 13 and left and right side walls 14 and 14 which are provided upright on the periphery of a rectangular bottom wall surface 6, and the bottom wall surface 6 has a drive shaft of a recording / reproducing apparatus. Is formed in the reel hub of the tape reel 25. The position of the tape reel 25 is regulated in the horizontal direction of the cassette by a partition wall 5 which is erected on the upper wall surface 18 and the bottom wall surface 6 so as to surround the tape reel 25.

The upper and lower half cases 2 and 3 are integrally molded of a synthetic resin such as ABS. As shown in FIG.
20 are formed, and the convex portion is formed on the lower half case 3.
A rib 30 is formed at a position opposed to the rib 20, a recess 31 is formed in the rib 30, and an air hole 32 is provided to connect the recess 31 and the outside of the case. Further, the tip of the convex portion 20
21 and an air hole 33 connected to the side surface are formed. The outer diameter L of the tip 21 of the convex portion 20 is slightly larger than the inner diameter l of the concave portion 31.

The concave portion 31 and the convex portion 20 are welded together so that the upper and lower half cases 2 and 3 are overlapped and abutted at the final stage of the cassette assembly. This welding is performed by welding the welding horn 80 on the upper half case 2 and the lower half case 3 together.
Insert the cassette case with the support base 60 at the bottom of
Ultrasonic vibration is applied to the above-mentioned abutting portion by the welding horn 80, the suction hole 61 of the support base 60 is connected to the air hole 32, and suction is performed by suction means (not shown). Therefore, frictional heat is generated in the abutting portion and the contact portion begins to melt, and as shown in FIG. 3, the outer peripheral portion of the tip 21 and the inner peripheral portion of the recess 31 are melted to form a welded portion 35. At the same time, the tip 21 is inserted and welded into the recess 31 to complete the welding. At this time, the suction hole
By sucking air from 61, the fine resin powder 70 generated at the initial stage of welding is directly drawn into the inner space 36 side, or once discharged into the case, it is sucked through the air hole 33. It

In order to enhance the close contact between the suction holes 61 and the air holes 31, a close contact member 62 made of an elastic member or the like may be provided on the outer circumference of the opening of the suction holes 61.

Further, if the internal space 36 is made relatively large, the excess portion 38 of the resin melted in the welded portion 35 can be effectively drawn into the internal space 36.

In this way, by sucking from the air holes 32,
The fine powder 70 generated by the ultrasonic welding is very effectively removed from the case. Further, since the excess portion 38 that has melted does not flow out of the joint portion, the outer diameter dimension of the joint portion is changed by welding, or when the weld portion is adjacent to the outside of the case, welding that impairs the appearance is required. Can be prevented.

Further, in this embodiment, the lower half case 3 is provided with a rib 40 at a position on the front side of the cassette, and the upper half case 2 is provided with a convex portion 50 that fits into the rib 40. Similar to the convex portion 20, the convex portion 50 has an air hole 33 that communicates the internal space 36 with the inside of the case. The rib 40 is configured to surround a positioning hole 60 into which a cassette positioning means such as a positioning pin is inserted when the cassette case is loaded in the recording / reproducing apparatus.

A stepped recess 41 is formed in the rib 40, and the air hole 32 of the stepped recess 41 communicates with the positioning hole 59 and also serves as a so-called positioning hole. Therefore, the opening of the suction hole 61 formed in the support base 60 is formed to be large corresponding to the positioning hole 59. The tip portion of the convex portion 50 is configured as a tapered stepped tip 51 corresponding to the stepped recessed portion 41, and the stepped tip 51 reaches the step portion 42 in the middle step of the recessed portion 41. The welded portion 35 is formed by being inserted. Since the stepped portion 43 is formed between the air hole 32 and the recess 41, the resin melted at the time of welding does not flow into the positioning hole 60.

In the present invention, it goes without saying that the formation positional relationship between the concave portion 31 and the convex portion 20 may be reversed from the above embodiment.

In the above-described embodiment, the welded portion is located inside the cassette case. However, the present invention is not limited to this, and the position where the recess 31 is formed as shown in FIG. The side wall (including the corner portion of the case) may be used, and the air hole 33 may not be connected to the inside of the case but may be opened outside the case as shown by an imaginary line.

Further, as shown in FIG. 6, the present invention may be arranged such that the air hole 33 communicating with the inside of the case and the air hole 32 communicating with the suction hole 61 are provided in the rib 30 of the lower half case 3.

In the above embodiment, the welded portion 35 has a width in the thickness direction of the case. However, as shown in FIG. 7, the present invention has a protrusion 2a on the tip end surface of the protrusion 20 and the protrusion 20 And rib 30
There is no problem even if the structure is such that the tip surfaces of and are adhered.

In the above embodiment, the magnetic tape cassette for VHS type VTR has been described, but the present invention is not limited to this, a magnetic tape cassette for β type VTR, a magnetic tape cassette for 8 mm video, an audio tape. Not limited to magnetic tape cassettes such as cassettes, it is most suitable to use a small and lightweight case such as a magnetic disk cartridge and a magneto-optical disk cartridge, and it is needless to say that it can be applied to all other plastic cases.

(Effects of the Invention) As described above, the present invention is provided with an air hole at the abutting portion where ultrasonic welding is performed and sucks through the air hole at the time of welding. The fine powder can be sucked out from the air holes, and the fine powder generated by ultrasonic welding can be removed very effectively outside the case, and the inside of the case can be kept clean.

Further, if a gap such as an internal space is formed in the abutting portion, the excess portion of the resin melted at the welded portion can be effectively drawn into the internal space, and the outer diameter of the joint portion may be changed by the welding. Moreover, when the welded portion is adjacent to the outside of the case, it is possible to provide a plastic case in which the welded resin does not protrude from the outside.

[Brief description of drawings]

FIG. 1 is a schematic exploded perspective view of a magnetic tape cassette for a VHS (registered trademark) type VTR according to the present invention. FIGS. 2 to 4 are schematic sectional views of a welded portion, and FIGS. FIGS. 8 and 9 are schematic cross-sectional views showing a conventional welding structure according to another embodiment of the present invention. (Reference numeral in the figure) 2 ... upper half case, 2a ... protrusion, 3 ... lower cassette half, 5 ... bulkhead, 6 ... bottom wall surface, 7 ... shaft insertion port, 12 ... front side wall, 13 ... … Rear wall, 14 …… left and right sidewalls,
15 …… Window opening, 16 …… Recess, 18 …… Upper wall, 20, 50…
… Convex part, 21 …… tip, 22 …… guard panel, 25 …… tape reel, 26 …… magnetic tape, 30,40 …… rib, 31 ……
Recess, 32, 33 ... Air hole, 35 ... Welding part, 36 ... Internal space, 38 ... Excess part, 41 ... Stepped recess, 42, 43 ... Stepped part, 51 ... Stepped tip, 59 …… Positioning hole, 60 …… Support base, 61 …… Suction hole, 62 …… Adhesive member, 70 …… Fine powder, 80
...... A welding horn.

Claims (2)

[Scope of utility model registration request] 1. A plastic case constituted by stacking upper and lower half cases and fixing and welding the welded butted portions of the upper and lower half cases by applying ultrasonic vibrations, and an internal space is formed inside the butted portions. And a plastic case which has at least one air hole communicating with the internal space and which is sucked and sucked from the air hole during the welding. 2. The plastic case according to claim 1 is used as a cassette case of a magnetic tape cassette, and two or more air holes which communicate with the outside of the cassette case and the outside or inside of the case are formed. A magnetic tape cassette characterized by that.