JPH058156Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a cap for a writing instrument.

[Prior art and its problems]

For writing instruments that use water-based ink, such as fountain pens, when the cap is attached to the writing instrument itself,
In order to prevent ink evaporation and to engage the cap, an inner cylinder made of synthetic resin is placed inside the cap body, and the pen body is sealed with this inner cylinder, and the abutment side of the inner cylinder is connected to the writing instrument body. There are many things that are engaged with. However, when the internal volume of this inner cylinder is large,
When writing, when the writing instrument body is removed from the cap, the inner cylinder is in close contact with the writing instrument body at that moment, so the volume of the sealed space increases and the pressure around the pen body is reduced. Therefore, there are problems such as an excessive amount of ink being sucked out, staining hands, etc., and smudging while writing. For this purpose, an airtight part with a small inner volume is provided at the bottom side of the inner cylinder to seal the pen body, and a locking part that engages with the annular protrusion of the writing instrument body is formed at the apex side, and the airtight part and the locking part A ventilation hole is bored between the two. however,
This inner cylinder is injection molded from synthetic resin, but in order to create the ventilation holes, secondary processing is required after injection molding. Therefore, there is a problem that the number of manufacturing steps is increased and productivity is low.

[Purpose of invention]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a cap for a writing instrument that is easy to manufacture, has high productivity, and prevents ink from being sucked out excessively when the main body of the writing instrument is removed from the cap.

[Structure of the idea and its function]

The structure of the present invention has an airtight part that seals the pen body on the back side, a locking part that engages with the annular protrusion of the writing instrument body on the abutment side, and an inner cylinder injection-molded from synthetic resin as a cap. In a writing instrument cap disposed inside the main body, a shoulder is formed on the outer periphery of this inner cylinder, and this shoulder is equal to or slightly larger than the wall thickness of the inner cylinder from the shoulder to the locking part. It is characterized by a ventilation slit extending from the shoulder toward the locking portion.

That is, the mold for molding the inner cylinder is composed of a fixed mold for molding the inner peripheral surface of the inner cylinder and a movable mold for molding the outer peripheral surface. A ventilation slit is formed in the direction from the shoulder of the inner cylinder to the locking part, which coincides with the direction of the cutting die of the mold. For this reason, a mold for forming this slit is provided in a movable mold,
If the slit mold is brought into contact with the stationary mold when the mold is clamped, slits for ventilation can also be formed during injection molding. Therefore, secondary processing after injection molding becomes unnecessary, simplifying the process and improving productivity.

〔Example〕

The present invention will be specifically described below based on embodiments shown in the drawings.

In FIG. 1, a cap body 1 is pipe-shaped, and only a notch into which a clip 2 is inserted is formed at the tail end opening. Clip 2 C
The letter-shaped fixing part is fitted into the lid plug 3, and the lid plug 3 is provided with a press-fit part 31 that is somewhat larger than the inner diameter of the cap body 1, and a small-diameter part 32 in front of the press-fit part 31. 31 is press-fitted into the tail end opening of the cap body 1 and firmly fixed. An inner cylinder 4 injection molded from synthetic resin is fitted into this small diameter portion 32. An annular protrusion 41 with a tapered inner surface is formed inside the inner cylinder 4, and a space deeper than this is an airtight part 42, and this annular protrusion 41 is in close contact with the tip of the writing instrument body. to seal the pen body. A locking pawl 43 protrudes from the abutment side of the inner cylinder 4 and engages with an annular projection of the writing instrument main body. However, an annular recess may be formed in place of the locking pawl 43, and the annular protrusion of the writing instrument body may fit into this annular recess. A shoulder portion 44, which is equal to or slightly larger than the wall thickness of the inner cylinder 4, is formed approximately in the middle of the outer periphery of the inner cylinder 4, so that the outer diameter thereof is increased.
An axial slit 45 is formed from this shoulder portion 44 toward the locking pawl 43, and the inside of the inner cylinder 4 communicates with the outside through this slit 45.

When this cap is attached to the writing instrument body, the pen body is sealed by the airtight portion 42, and the locking claw 43, which is a locking portion, engages with the annular projection of the writing instrument body, so that it does not fall off. When the main body of the writing instrument is removed from the cap when writing, the air-tight portion 42 has a small internal volume and a tapered inner surface, so air immediately enters the pen body and the area around the pen body is not in a reduced pressure state. Therefore, the ink will not be sucked out excessively and will not stain your hands or the like.
This solves the problem of ink dripping while writing.

Next, a mold structure for injection molding the inner cylinder 4 will be explained. The fixed mold 5 is a mold for molding the inner surface of the inner cylinder 4, and the movable mold 6 is a mold for molding the outer surface of the inner cylinder 4. When the molds are clamped, the cavity 7 is defined as shown in FIG. be done. Then, the molten synthetic resin from the runner and gate (not shown) flows into the cavity 7.
The inner cylinder 4 is molded. Here, the slit mold 61 is integrated with the movable mold 6,
When the molds are clamped, the slit mold 61 comes into contact with the fixed mold 5. Therefore, the slit 45 is molded at the same time during injection molding. This eliminates the need for secondary processing after injection molding, which simplifies the process and improves productivity.

[Effect of idea]

As explained above, in the cap of the present invention, the slit for ventilation is formed in the axial direction from the shoulder of the inner cylinder, so the slit is simultaneously molded during injection molding, and the second cap is used to form the ventilation hole. No further processing is required. Therefore, it is possible to provide a writing instrument cap that is easy to manufacture, has high productivity, and prevents ink from being sucked out excessively when the writing instrument body is removed from the cap.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the present invention, FIG. 2 is an explanatory view of the mold structure, and FIG. 3 is a sectional view taken along the - line in FIG. 2. 1...Cap body, 2...Clip, 3...
Lid stopper, 4...Inner cylinder, 42...Airtight part, 43...Latching claw, 44...Shoulder part, 45...Slit, 5...
Fixed type, 6...Movable type, 61...Slit mold.

Claims (1)

[Scope of Claim for Utility Model Registration] The cap body consists of an inner cylinder made of synthetic resin that has an airtight part for sealing the pen body on the back side and a locking part that engages with the annular protrusion of the writing instrument body on the abutment side. In the writing instrument cap disposed inside, a shoulder is formed on the outer periphery of the inner cylinder, and this shoulder is equal to or slightly larger than the wall thickness of the inner cylinder from the shoulder to the locking part. 1. A cap for a writing instrument, characterized in that a slit for ventilation is provided extending from the portion toward the locking portion.