JPH0415511Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The invention has a double inner cap inside the outer cap that is attached to the small diameter part of the tip of the writing instrument barrel and airtightly shields the core. This relates to a so-called medium cap type cap.

(Prior Art) Caps of the inner cap type are used in writing instruments such as markers that require strong prevention of ink evaporation, but unless the inner cap is completely fitted, its existence has little significance.

Therefore, in order to check whether the inner cap is completely fitted, a method is generally adopted in which an undercut is provided on the inner surface of the inner cap to engage with a protrusion provided on the writing instrument, and the inner cap is click-fitted. There is.

However, in conventional caps, the degree of this click is so small that the fit cannot be clearly confirmed, and the reliability of the click fit is low.

In order to solve this problem and increase the degree of click, it is necessary to make the undercut part on the inner surface of the middle cap higher, which engages with the protrusion etc. provided around the small diameter part of the tip of the writing instrument barrel. Although this can be achieved easily, simply increasing the height of the undercut portion causes a problem in that when the cap is to be removed, the undercut portion obstructs and makes it difficult to remove the cap.

Therefore, in order to increase the degree of click and to make it easier to remove the cap, the inner cap is made of a material such as a metal plate that is easily deformed by elasticity, separately from the outer cap, and the peripheral wall of the inner cap is split in the axial direction. Measures have been taken to make the middle cap easier to elastically deform.

However, the former has the disadvantage of increasing the number of parts and assembly man-hours, resulting in high costs, and the latter has the risk of damaging the sealing function of the inner cap.

(Problems to be Solved by the Invention) Therefore, the present invention aims to improve the degree of click of the inner cap by increasing the undercut portion provided on the inner surface of the inner cap without making it difficult to remove the cap. To provide a cap for a writing instrument which can reduce costs without increasing the number of parts or assembly man-hours, and which does not impair the sealing function of the inner cap.

(Means for Solving the Problems) In order to achieve the above object, the cap of the writing instrument of the present invention has an outer cap part that fits into the large diameter part of the tip of the writing instrument, and a small diameter part of the tip from which the core of the writing instrument protrudes. It is constructed by integrally molding an inner cap that fits airtight into the inner cap and prevents ink from drying up.
An undercut portion is provided on the inner surface of the inner cap that extends slightly inward from the mouth edge to engage with a protrusion provided around the outer surface of the small diameter portion of the writing instrument's tip, and an undercut portion is provided on the peripheral wall of the middle cap portion from the mouth edge. A required number of axial divisions are provided up to the vicinity of the undercut portion without exceeding the undercut portion.

(Embodiment) The figures show an embodiment of the present invention, in which Fig. 1 is a longitudinal cross-sectional view showing a state in which a cap 2 is attached to a writing instrument (marker) 1, and Fig. 2 is a line taken along line A-A in Fig. 1. 2 is an enlarged cross-sectional view of the writing instrument 1, and the cap 2 has an outer cap portion 4 that fits into the large diameter portion 3 of the tip of the writing instrument 1;
It is constructed by integrally molding an inner cap part 7 which airtightly fits into the small diameter part 6 of the tip from which the core body 5 of the writing instrument protrudes to prevent ink from drying up, and the opening of the inner cap part 7 in the cap 2 An undercut portion 9 that engages with a protrusion 8 provided around the outer surface of the small diameter portion 6 at the tip of the writing instrument 1 is formed on the inner surface slightly inward from the edge, and an opening is formed on the peripheral wall of the middle cap portion 7. A plurality of axial splits 10 are provided at intermediate locations of each undercut portion 9 in the circumferential direction within a range from the edge to the vicinity of the undercut portion 9 without exceeding the undercut portion 9.

(Operations and Effects) As described above, the present invention has an undercut portion that engages with a protrusion provided on the outer surface of the small diameter portion of the tip of the writing instrument on the inner surface slightly inside from the mouth edge of the middle cap portion. At the same time, since the peripheral wall of the middle cap part is divided in the axial direction from the mouth edge to the vicinity of the undercut part, there is no radial deformation in the area from the mouth edge of the middle cap part to the vicinity of the undercut part. Therefore, even if the height of the undercut increases, the cap can be easily removed. Therefore, the height of the undercut can be increased to increase the click and improve the reliability of the click fit. In addition to this, the present invention has the effect that the inner cap is integrally molded with the outer cap without using a separate material, reducing the number of parts and assembly man-hours to the necessary minimum. In addition, since the split in the middle cap is limited to a range that does not extend beyond the mouth edge to the undercut, the sealing performance of the middle cap is not impaired, and the above purpose is achieved. It has the effect of completely achieving the following.

[Brief explanation of drawings]

The figures show an embodiment of the present invention, with Fig. 1 being a longitudinal sectional view showing how it is fitted into a writing instrument, and Fig.
FIG. 2 is an enlarged cross-sectional view taken along line A-A in the figure. 1...Writing instrument, 2...Cap, 3...Large diameter part of the tip of the writing instrument, 4...Outer cap part, 5... Core body, 6...Small diameter part of the tip of the writing instrument, 7...Medium cap, 8... ... Projection, 9 ... Undercut part, 10
...Discount.

Claims (1)

[Scope of utility model registration request] It is constructed by integrally molding an outer cap part that fits into the large diameter part of the tip of the writing instrument, and an inner cap part that fits airtightly into the small diameter part of the tip from which the core of the writing instrument protrudes to prevent ink from drying up. An undercut part is provided on the inner surface of the middle cap part, which extends slightly inward from the mouth edge part, and which engages with a protrusion provided on the outer surface of the small diameter part of the tip of the writing instrument. A cap for a writing instrument, characterized in that a required number of axial divisions are provided in the range from the undercut portion to the vicinity of the undercut portion without exceeding the undercut portion.