JP2001179753A - Resin shaft body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of a structure that a part where resins are butted to each other (generally, this part is called 'weld') is positioned at a part where a groove part is formed, so that not only the strength is deteriorated by the groove part but also the entire strength is further undermined on account of the resin-butted part. SOLUTION: This resin shaft body is made of the resin and has the groove part 14 formed on the surface of a shaft cylinder, in the longitudinal direction, at a position reached after proper rotation of the shaft body from the resin- butted part 15 when the shaft body is molded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin barrel formed by injection molding or the like.

[0002]

2. Description of the Related Art A writing implement having a plurality of grooves formed in a longitudinal direction on a surface of a shaft cylinder in order to improve appearance and feel to fingers is known. The gate is positioned using the groove so that a gate mark is formed in the groove. A groove is also formed at a position facing the gate position.

[0003]

However, in the above-described conventional technology, a portion where resin is fitted (generally, a portion referred to as a "weld") is formed in a portion where a groove is formed. Therefore, in addition to the weakening of the strength due to the grooves, the structure has been further reduced.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a resin-made shaft, which is a resin-made shaft, and which, when molded, is provided with a longitudinal portion of a surface of a shaft cylinder at a position appropriately rotated from a resin joining portion. The gist is that a groove is formed in the direction.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first example will be described with reference to FIG. This is an example in which the present invention is applied to a mechanical pencil. Inside the front shaft 1, a lead tank 2 capable of accommodating a plurality of leads is slidably disposed. A chuck body 3 for holding and releasing the core is fixed in front of the core tank 2, and a chuck ring 4 for opening and closing the chuck body 3 is surrounded in front of the chuck body 3. . And those core tanks 2
The chuck body 3 and the like are urged rearward by a resilient member 5 such as a coil spring. In addition, the front shaft 1
A tip member 6 is detachably attached to the tip of the body by means such as screwing, and a core detent member 7 for preventing retraction of the core is integrally formed inside the tip member 6. Alternatively, it may be constituted by a separate member and fixed by means such as press fitting. Reference numeral 8 denotes a core protection tube integrally formed at the tip of the tip member, but this core protection tube may also be formed as a separate member and fixed by means such as press fitting.

The front shaft 1 has a maximum diameter at a gripping portion (grip portion 9), and a knurl is formed in the gripping portion in the circumferential direction. The diameter is not uniform as a whole, but is gradually reduced toward the front and rear. That is, the central portion is a large diameter portion.
Further, a gate mark 10 to be described later is formed on the grip 9 at two positions facing each other. The inner surface of the front end of the front shaft 1 is chamfered (chamfered portion 11) (enlarged view; see FIG. 2) to have a conical shape. If burrs 12 are formed on the outer portion during molding, the chuck ring 4 is caught by the burrs, which causes a malfunction (variation in the protrusion amount of the core) (FIG. 3).
Reference). As a modified example, a structure as shown in FIG. 4 may be used. That is, instead of chamfering, a right-angled concave portion 1 is formed on the inner surface of the front end.
3 may be formed. Further, a plurality of grooves 14 (specifically, four places: see FIG. 5) are formed in the longitudinal direction behind the grip 9 on the front shaft 1. Also, between the grooves 14 and below the extension thereof, the gate traces 10 formed during molding are located (see FIG. 1). That is, the resin flows from the gate and the front shaft 1 is formed. Then, the operation of the resin that has flowed in is dispersed in the left-right direction from each gate, goes around, and joins and joins the other two groove portions 14 (joining portion 15: see FIG. 5). This joint portion is generally called "weld".

A rear shaft 16 is fixed to the rear portion of the core tank 2 by means such as fitting of unevenness, but may be formed integrally with the core 2 tank. In the case of integral molding, the core tank 2 and the rear shaft 16 may be formed of the same material. However, considering that the chuck body 3 is pressed into the front end of the core tank 2, the core tank 2 is A relatively soft material may be used, and the rear shaft 16 may be integrally formed using a hard material, for example, by a so-called two-color (different material) molding technique. The rear shaft 16 includes a small-diameter portion 17 to be fitted into the core tank 2 and a large-diameter portion 19 integrally formed with a clip 18 and the like. Although the rear end of the core tank 2 protrudes from the rear end of the front shaft 1, it is intended to facilitate the assembly of the rear shaft 16 to the core tank 2 and the accuracy of positioning. It may be in a state of being immersed in the front shaft 1. As described above, the clip 18 is formed integrally with the rear shaft 16, and a through hole 21 is formed in the base 20.
"Shrinkage (dent due to resin shrinkage)" due to molding of the base portion 20 on the surface of the clip 18 is prevented as much as possible.

The front end of the narrow diameter portion of the rear shaft 16 extends to the middle of the core tank 2 and has an inner diameter smaller than the inner diameter of the core tank 2. When the core is stored in the core tank 2, the rear end of the core is connected to the small-diameter portion 17.
Abuts against the inner surface of the front part of the vehicle. That is,
By floating the rear end of the lead from the inner surface of the lead tank 2, sticking of the lead to the lead tank is prevented. The sticking may be caused by static electricity, core oil (oil contained in the core), or moisture.

On the inner surface of the large diameter portion 19 of the rear shaft 16, there are provided a plurality of ribs 2 for restricting the eraser 23 from entering below.
2 are formed at equal intervals. Further, the large diameter portion 19
The inner surface of the rear part has a holding hole 24 for holding the eraser 23.
Are formed, and a plurality of small ribs are also formed in the holding hole 24. These ribs are formed to absorb variations in the dimensions of the holding hole 24 and the eraser 23 itself. A cap 25 that protects the eraser 23 when not in use is detachably attached to the rear end of the large diameter portion 19, and a plurality of through holes 26 are formed in the top surface of the cap 25. ing. Even if a child swallows, a certain amount of air is being circulated. A projection 27 is formed on a part of the outer periphery of the eraser cap 25. The eraser cap 25 is removed from the large-diameter portion 19 to prevent rolling when the device is placed on a desk or the like. Further, a slit 28 is formed below the projection 27, so that the lower end of the eraser cap 25 can be easily opened and closed when attaching and detaching. That is, the material fatigue of the eraser cap 25 is prevented.

On the other hand, the front portion of the large diameter portion 19 is once reduced in diameter, but has an edge portion 28 having a semicircular cross section. The outer diameter of the edge 28 is substantially equal to the outer diameter of the rear end of the front shaft 1. When an excessively large lead-out operation is performed, the edge 28 abuts on the rear end of the front shaft 1 to prevent breakage of the lead-out mechanism.

A modification is shown in FIG. 7 and will be described. Gate 10
This is an example in which are combined into one. More specifically, the groove portions 14 are formed at two positions rotated by 90 degrees in the circumferential direction from the gate position 10, and the grooves 14 are rotated by 180 degrees, that is,
The groove 14 is not formed at a position facing the gate 10. This is because the position facing the gate 10 becomes a weld (alignment portion 15). A further modification is shown in FIG. 8 and described. This is an example in which the gate 10 is located in the groove 14 as in the related art. However, also in this example, the groove portion 14 is not formed at the position where the weld (the alignment portion 15) occurs. Specifically, the groove 14 is formed at a position rotated by about 30 degrees in the circumferential direction from the gate mark 10. In this example, the groove is shallow, and an inclined surface or a circular arc is formed at the end in order to improve the releasability from the mold at the time of molding.

[0012]

According to the present invention, a resin shaft is formed, and when molded, the groove is formed in the longitudinal direction of the surface of the shaft cylinder at a position rotated appropriately from the mating portion of the resin, so that the strength is reduced by the groove. Nevertheless, further weakening due to welding can be prevented.

[Brief description of the drawings]

FIG. 1 is a longitudinal half sectional view showing an example of the present invention.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is a diagram corresponding to FIG. 2, showing occurrence of burrs due to molding.

FIG. 4 is a diagram showing a modification example corresponding to FIG. 2;

FIG. 5 is a sectional view taken along line AA of FIG. 1;

FIG. 6 is a front view of FIG. 1;

FIG. 7 is a sectional view taken along line AA of FIG. 1, showing a modification.

FIG. 8 is a sectional view taken along line AA of FIG. 1, showing a further modified example.

[Explanation of symbols]

 Reference Signs List 1 front shaft 2 core tank 3 chuck body 4 chuck ring 5 elastic / repellent member 6 tip member 7 core detent portion 8 core protection tube 9 gripping portion (knurl) 10 gate mark 11 chamfered portion 12 burr 13 concave portion 14 groove 15 weld 16) Rear shaft 17 Small diameter portion 18 Clip 19 Large diameter portion 20 Base 21 Through hole 22 Vertical rib 23 Eraser 24 Nipping hole 25 Eraser cap 26 Through hole 27 Convex portion 28 Edge

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Claims (3)

[Claims] 1. A resin shaft, wherein a groove is formed in a longitudinal direction of a surface of a shaft cylinder at a position where the resin is appropriately rotated from a mating portion of the resin when molded. 2. The resin barrel according to claim 1, wherein a gate mark is provided at a position facing a side surface of the barrel.
A resin shaft cylinder, wherein the groove is formed at a position rotated by approximately 45 degrees in a circumferential direction from the gate mark. 3. The resin shaft cylinder according to claim 2, wherein the groove is formed at a position rotated by approximately 45 degrees from the extension of the gate mark.