JPS6140198B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a simple and effective device for closing the tail end of a marking pen shaft in an airtight manner and always in the correct shape without using a tail plug.

As shown in FIG. 3, the inventor of the present invention presses the tail end of a synthetic resin pen barrel P into a metal heat retention mold 2 screwed onto a support 1 as shown in FIG. We have proposed a marking pen shaft that eliminates the tail plug that closes the end of the pen shaft by melting this part by heating with a nichrome rod 4 inserted into the pen shaft.

However, if the pen is melted and closed by a simple mold, high heat is concentrated in the center of the axis of the tail end of the pen shaft, and the high temperature heat in the mold accumulates and becomes high pressure, which is applied to the outer surface of the closed end. It has been recognized that this part often becomes distorted, resulting in irregular shapes and lowering the commercial value.

In the present invention, in order to eliminate the above-mentioned disadvantages, as a result of research, we have finally obtained a marking pen shaft with a closed tail end that is always in a regular shape and has a good appearance using the following device.

Now, to explain this device with reference to the drawings of the embodiment,
At the top of the axial line of a cap-shaped mold 2 whose inner diameter matches the outer diameter of a pen barrel P made of thermoplastic synthetic resin, a short cylindrical neck 3 having a diameter smaller than the inner diameter of the mold and having a heat dissipation hole h bored in the peripheral wall is provided. A hollow drum shape is provided on the inside of the neck, and the outer diameter of the inner end tsuba g ₁ is slightly smaller than the inner diameter of the neck, and the outer diameter of the outer end tsuba g ₂ matches the inner diameter of the neck 3. A metal core 5 is interposed to form an annular cavity R between the outer peripheral wall of the metal core and the inner peripheral wall of the neck 3.
A ring-shaped gap S is formed between the inner end of the tsuba g ₁ and the inner end of the neck 3.
A nichrome rod 4, whose outer end is connected to the electrode W, is inserted onto the central axis of the inner core, and its tip is fixed to the center of the inner end of the flange _g1 , thereby forming the cap-shaped mold 2.
It is screwed N and supported by a support 1 having a circulating water hole H inside. The protrusion x formed on the inner surface indicates ink-impregnated cotton inserted into the pen barrel P.

Since this device is configured as described above, when the tail end of the pen barrel P made of thermoplastic synthetic resin is to be closed-molded using this device, the nichrome rod 4 is attached from the electrode W in advance.
When a current is applied to the temperature of about 800°C, the drum-shaped core metal 5 connected to the tip of the nichrome rod gradually retains heat from the inner end flange _g1 , and furthermore, the cap-shaped core metal 5 connects to the tip of the nichrome rod gradually accumulates in heat from the outer end flange of the core metal. Heat is transferred to mold 2. Therefore, if the ink-impregnated cotton x is inserted in advance into the thermoplastic synthetic resin pen barrel P with an outer diameter of about 9 mm and a wall thickness of about 1 mm, and its tail end is inserted into the cap-shaped mold 2, the core metal 5 will remain. As a result of the experiment, the heat distribution is highest on the inner end flange _g1 surface of the core metal 5.
The temperature reached 200℃, and the temperature decreased slightly on _{the two} sides of the outer end flange (150°C).
℃, and then at the shoulder of the cap-shaped mold 2, where the heat was transferred via the core metal and the neck 3, the hot air filling the cavity R in the neck 3 indirectly spreads to a temperature of 40℃. Since the heat distribution state is reduced, the inner circumferential wall of the insertion end of the pen shaft P into the mold 2 is softened by the high-temperature air at the inner end of the core metal 5, and as it is pushed in, the inner peripheral wall gradually receives heat without difficulty. It is uniformly bent inward and finally at the inner top of the cap-shaped mold 2, surplus heat from the annular gap between the high-temperature inner end surface of the core metal 5 and the cap-shaped mold 2 flows into the inner space R of the neck 3. Since the heat is radiated to the outside from the heat radiation hole h through the annular gap, the inner end flange g of the core metal ₅ is heated to a high temperature. The bent inner surface of the portion becomes soft and has a small resistance, so it protrudes as a mountain-like convex portion t, and at this time, it is bonded and solidified with the ink-impregnated cotton x, thereby immovably holding the ink-impregnated cotton.

That is, according to the apparatus of the present invention, the temperature is highest at the inner end flange surface of the drum-shaped core, the lowest temperature is at the shoulder of the mold, and the annular gap between the shoulder and the inner end flange of the core is heated. As the temperature is slightly lowered due to heat dissipation and the resistance inside the mold is eliminated, the end of the pen shaft gradually and smoothly bends inward and finally reaches the inner end flange surface of the core metal. It becomes a concave plane and is closed, and the inner part, which is the softest, becomes a convex part that rises like a mountain.As it cools and solidifies, the tail end is always closed in a regular shape without distortion. This is a simple yet extremely advantageous invention that has the following effects.

[Brief explanation of the drawing]

The drawings show an embodiment, in which Fig. 1 is a longitudinal cross-sectional side view of the main part of the device of the present invention, Fig. 2 is a side view with a cutaway of the tail of the marking pen shaft obtained by the same device, and Fig. 3 1 is a longitudinal sectional side view of a main part of a conventional device. 2 is a cap-shaped mold, 3 is a neck, 4 is a nichrome rod, 5
is Nakako gold, g ₁ is the inner end tsuba, g ₂ is the outer end tsuba, h is the radiation hole, R is the annular cavity, S is the ring gap, L is the concave plane, t is the convex part, P is the pen The axis and W are electrodes.

Claims (1)

[Claims] 1. At the top of the axis of a cap-shaped mold with an inner diameter that matches the outer shape of the tail end of the pen shaft, a short cylindrical neck with an outer diameter smaller than the inner diameter of the mold and with heat dissipation holes bored in the peripheral wall is connected. Then, a hollow drum-shaped core metal is interposed inside the neck, the outer diameter of the inner end of the tsuba is slightly smaller than the inner diameter of the neck, and the outer diameter of the outer end of the tsuba matches the inner diameter of the neck. An annular cavity is formed between the outer wall of the metal core and the inner wall of the neck, and a ring-shaped gap is formed between the collar of the inner end of the metal core and the inner end of the neck, and the outer end is arranged on the inner axis of the metal core. A marking pen shaft made of synthetic resin, in which a nichrome rod connected to an electrode is inserted, its tip is fixed to the center of the flange at the inner end, and a cap-shaped mold is screwed and supported on a support metal with a water passage hole inside. Integral occlusion device at the tail end.