JPH0521378U - Tape cartridge - Google Patents

Abstract

(57) [Summary] [Purpose] The upper and lower cases that make up the main unit case are securely screwed together with tapping screws to eliminate the screw back phenomenon and to prevent loosening. [Structure] An upper case 1a and a lower case 1b, which constitute a main body case 1, are fastened with a tapping screw 2. At the screw fastening positions of the upper and lower cases 1a and 1b, a screw receiving surface 19 that receives a screw seat surface 18 of a head 15 of the screw 2 is provided around the screw insertion hole 14 through which the tapping screw 2 is inserted.
On the screw receiving surface 19, a large number of elastically deformable convex portions 20 are radially provided around the screw insertion hole 14. Each convex portion 20 comes into contact with the screw seat surface 18 and falls down on the screw receiving surface 19.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a tape cartridge having an improved screw fastening structure for a main body case.

[0002]

[Prior Art]

 Taking the tape cartridge shown in FIG. 2 as an example, the main body case 1 is made by abutting the plastic upper and lower cases 1a and 1b, and the four corners and the front center part are screwed together by tapping screws 2 at a total of five places. It is concluded. As shown in FIG. 3, a boss 11 is projectingly provided on the lower case 1b side at the screw fastening portion, and a boss hole 12 into which the boss 11 is fitted is provided on the upper case 1a side. A screw pilot hole 13 and a screw insertion hole 14 for inserting the tapping screw 2 are provided in the boss 11 and the boss hole 12, respectively, in a vertically concentric manner. Then, the tapping screw 2 is screwed from the upper case 1a side into the screw lower hole 13 on the lower case 1b side through the screw insertion hole 14 to fasten the upper and lower cases 1a and 1b.

Recent tape cartridges are required to improve sound quality characteristics and image quality characteristics of recorded information and physical characteristics during use. Therefore, the upper and lower cases 1a and 1b tend to be formed of a soft and heavy material such as a composite plastic material obtained by mixing a filler in a polyolefin-based plastic base such as polypropylene (Japanese Patent Laid-Open No. 62-7182). ..

[0004]

[Problems to be solved by the device]

 However, in such a tape cartridge, in the screw tightening process, the tapping screw 2 is screwed more than the limit because the molding material of the main body case 1 is soft, and the thread groove to be formed in the screw hole 13 may be cut. there were. In that case, the thread groove on the body case 1 side loses the shape conforming to the unevenness of the thread of the tapping screw 2. Therefore, a so-called screw fool phenomenon occurs in which the tapping screw 2 is not locked to the main body case 1 while maintaining an optimum frictional force. This screw stupid phenomenon occurs because the tapping screw 2 is screwed with a screwdriver equipped with a torque limiter, but the timing of the torque limiter's activation is delayed because the material of the case to be screwed is soft. ..

A washer or the like is generally used as a measure to prevent the screws from loosening, but it is not preferable to apply this to the screw fastening portion of the tape cartridge because it leads to an increase in the number of parts and a decrease in assembly workability. Therefore, an object of the present invention is to improve a screw fastening portion to eliminate a screw back phenomenon and to obtain a tape cartridge which is also advantageous in preventing loosening of the screw.

[0006]

[Means for Solving the Problems]

 The present invention is composed of an upper case 1a and a lower case 1b, in which the main body case 1 is butted against each other and fastened with a tapping screw 2, and at the screw fastening points of the upper case 1a and the lower case 1b, the screw insertion hole 14 In a tape cartridge having a screw bearing surface 19 for receiving the screw bearing surface 18 of the head portion 15 of the screw 2, the screw bearing surface 19 is formed in an uneven shape having an elastically deformable convex portion 20. Is characterized by.

The convex portion 20 is obliquely provided on the screw receiving surface 19 so as to fall in the screwing direction of the tapping screw 2. Further, a large number of protrusions 20 are radially projected around the screw insertion hole 14, and the pitch P between the adjacent protrusions 20 is set to be larger than the protrusion height H of each protrusion 20.

[0008]

[Action]

 As the tapping screw 2 is tightened, the convex portion 20 formed on the screw receiving surface 19 as shown in FIG. 5 shows the force of the rotational direction component of the screw seat surface 18 (arrow a) and the component of the screw advancing direction. The resultant force (arrow c) with the force (arrow b) works, and the upper end of the convex portion 20 is pushed down to the lower right in the figure. At the same time, the screw seat surface 18 receives the reaction force thereof, and the upper end of the convex portion 20 receives the force indicated by the arrow d in the upper left direction of the drawing. Since this force includes a force having a component in the direction opposite to the traveling direction of the screw, the screw seat surface 18 receives resistance to rotation. Therefore, when the screw seat surface 18 comes into contact with the convex portion 20 when tightening the screw with the driver, effective tightening resistance is generated, and the tightening limit of the screw is reliably detected by the torque limiter or the like.

[0009]

[Effect of the device]

 According to the present invention, it is possible to prevent the tapping screw 2 from being tightened more than the limit when assembling the tape cartridge, so that the screw thread should be tightened within the range in which the screw thread can maintain the optimum frictional force with respect to the screw groove. It can be done easily. Further, without using extra parts such as washers, the elastic restoring force of the convex portion 20 can prevent the screw 2 from loosening, and can easily detect the limit of screw tightening to further improve the assembly workability. You can also

[0010]

【Example】

 1 to 5 show an embodiment in which the present invention is applied to a Philips type tape cartridge. In the main body case 1 of FIG. 2, a plastic upper case 1a and a lower case 1b are abutted against each other, and four corners and a front center portion of the main case 1 are fastened with tapping screws 2.

The body case 1 has drive shaft insertion holes 3, 3 penetrating in the vertical direction on the left and right sides of the central portion thereof, and the hubs 5, 5 on which the tape 4 is wound are formed on the left and right sides of the body case 1 respectively. It is rotatably arranged on the 3/3. The tape 4 is unwound from one hub 5 to the front of the case and wound on the other hub 4.

FIG. 3 shows each screw fastening portion into which the tapping screw 2 is screwed in. On the lower case 1b side, a boss 11 is formed so as to project upward from the butting surface with the upper case 1a. A boss hole 12 into which the boss 11 is fitted is formed in the.

A screw pilot hole 13 is formed in the center of the inside of the boss 11. In the upper case 1a, a screw insertion hole 14 that allows the tapping screw 2 to be inserted is provided in an upper wall of the boss hole 12, and an upper hole 16 having a diameter larger than the head 15 of the tapping screw 2 is provided above the screw insertion hole 14. Has been formed. That is, the upper hole 16 and the boss hole 12 are provided above and below the wall having the screw insertion hole 14.

The upper surface around the screw insertion hole 14, that is, the inner bottom surface of the upper hole 16 serves as a screw receiving surface 19 which receives the screw seat surface 18 below the head 15 when the tapping screw 2 is screwed in. There is. As shown in FIG. 1, the screw receiving surface 19 is provided with a large number of linear projections 20 that run in the radial direction around the screw insertion hole 14 and radially project at a predetermined pitch in the circumferential direction to form an uneven surface. Has become.

Although each of the convex portions 20 is elastically deformable, it is obliquely provided so as to easily fall down in the screwing direction of the tapping screw 2. That is, FIG. 4 is a vertical cross-sectional view of the two adjacent convex portions 20 on the screw receiving surface 19 as seen from the screw insertion hole 14 side. Since the tapping screw 2 has a right-hand thread on each convex portion 20, It has a tapered triangular cross-section with the left side wall inclined vertically. When the tapping screw 2 is a left-hand screw, it is formed in a triangular shape having an inclined surface opposite to this. The pitch P between the adjacent convex portions 20 and 20 is set to be larger than the protrusion height H of each convex portion 20 so that they do not overlap each other when the adjacent convex portions 20 and 20 fall down. is there.

When assembling the tape cartridge, the upper case 1a is butted against the lower case 1b. At this time, the boss 11 on the lower case 1b side is fitted into the boss hole 12 on the upper case 1a side for positioning. Next, the tapping screw 2 is screwed into the screw hole 13 of the boss 11 on the lower case 1b side from above the upper case 1a through the screw insertion hole 14 to fasten the upper and lower cases 1a and 1b.

The tapping screw 2 is screwed into the threaded hole 13 while forming a thread groove. When the screw 2 is completely screwed in, its head portion 15 sinks into the upper hole 16.

When the tapping screw 2 is screwed in and the screw seat surface 18 comes into contact with the convex portion 20 on the screw receiving surface 19, the convex portion 20 has a screw seat surface 18 as shown in FIG. The resultant force (arrow c) of the force of the rotation direction component (arrow a) and the force of the screw traveling direction component (arrow b) works, and the upper end of the convex portion 20 is pushed down to the lower right in the figure. At the same time, the screw seat surface 18 receives a force indicated by an arrow d from the upper end of the convex portion 20 in the upper left direction of the figure as a reaction force of this. Since the force indicated by the arrow d includes a force of a component in the direction opposite to the traveling direction of the screw, the screw seat surface 18 receives resistance to rotation.

Thus, effective tightening resistance is generated by the elastic restoring force of the convex portion 20. Therefore, in the screw tightening process of the tapping screw 2, if the change in the torque at the time of screwing is detected by, for example, the torque limiter, it is possible to prevent the screw from being tightened beyond the limit. That is, the screwing operation of the tapping screw 2 can be easily performed within a range in which the screw thread can maintain the optimum frictional force with respect to the screw groove. The elastic restoring force of the convex portion 20 also works to prevent the tapping screw 2 from loosening.

In addition to the above embodiment, the convex portion 20 can be formed in a curved shape that runs in the radial direction in a plan view, or can be formed in a state in which the phase is shifted by dividing it without forming a linear shape. Further, the protrusions 20 may be formed as small protrusions distributed over the entire screw receiving surface 19.

[Brief description of drawings]

FIG. 1 is a perspective view of a main part.

FIG. 2 is an overall plan view.

3 is a cross-sectional view taken along the line AA in FIG.

FIG. 4 is a vertical sectional view of a main part.

FIG. 5 is an explanatory diagram of a screw tightening process in FIG.

[Explanation of symbols]

 1 body case 2 tapping screw 11 boss 12 boss hole 13 screw pilot hole 14 screw insertion hole 16 upper hole 18 screw seat surface 19 screw receiving surface 20 convex portion

Claims (3)

[Scope of utility model registration request] 1. A main body case (1) is composed of an upper case (1a) and a lower case (1b) that are butted against each other and fastened with a tapping screw (2), at the screw fastening points of the upper case (1a) and the lower case (1b).
Around the screw insertion hole 14, there is provided a screw bearing surface 19 for receiving the screw bearing surface 18 of the head portion 15 of the screw 2, and the screw bearing surface 19 has an uneven shape having an elastically deformable convex portion 20. A tape cartridge characterized by being formed. 2. The tape cartridge according to claim 1, wherein a convex portion 20 is obliquely provided on the screw receiving surface 19 so as to fall in the screwing direction of the tapping screw 2. 3. A large number of convex portions 20 around the screw insertion hole 14.
3. The tape cartridge according to claim 1, wherein the tape cartridges are provided so as to radially project, and the pitch P between the adjacent protrusions 20 is set to be larger than the protrusion height H of each protrusion 20.