JP2002370489A - Mechanical pencil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mechanical pencil which enables low-cost manufacture of a fore end pipe and elimination of such a disadvantage as plugging of a lead by a simple check even when the disadvantage occurs in the fore end pipe. SOLUTION: A lead feeding mechanism is provided in an outer tube and the tip part of the fore end pipe 24 surrounding the lead is so provided as to project from the fore end opening 16a of a tip fitting 16 of the outer tube. The fore end pipe 24 can be fitted in and removed from the fore end opening 16a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanical pencil provided with a lead delivery mechanism for delivering a lead into an outer cylinder, and a tip end of a tip pipe surrounding the lead protruding from a tip opening of the outer cylinder. About.

[0002]

2. Description of the Related Art Conventionally, with this kind of mechanical pencil,
A distal end pipe surrounds the distal end of the core projecting outside from the distal end opening of the outer cylinder, and is mainly used to protect the core from breakage and the like. Known mechanical pencils can be broadly classified into a fixed type in which the tip pipe is completely fixed to the outer cylinder, and a slide type in which the tip pipe is movable with respect to the outer cylinder. Among these, as the fixed type, there are one integrally formed by extending integrally from a front end opening portion of a front tool constituting the front end portion of the outer cylinder and being drawn into a pipe shape, or any other fixed type. It is known that it is integrally fixed to a tool by means. In addition, as a slide type, it is inserted from the rear end of the front tool that constitutes the front end of the outer cylinder, and is movable within the front tool so that the front end of the front pipe can protrude from the front opening of the front tool. The arrangements are known.

[0003]

However, the conventional mechanical pencil has the following problems. That is, in the fixed type, when the tip pipe is formed integrally with the tip, the yield is poor, and when the tip pipe is defective, the entire tip must be replaced, which increases the manufacturing cost. There is a problem. Further, when the tip pipe is fixed to the leading tool, the fixing work is troublesome, and similarly, the manufacturing cost is increased.

[0004] In the slide type, a core pipe must be inserted from the rear end of the tool at the time of assembling, so that the tool is not caught in a step or the like formed inside the tool, without being hooked. Protruding the leading end of the core pipe from the opening at the end of the pipe takes time and also increases the manufacturing cost.

In any of the above types, when the core is clogged with the pipe at the end during use, the leading tool constituting the outer barrel is removed from the outer barrel body (normally, the outer barrel body and the leading tool are connected to each other). Has to be unscrewed), and the entire tool must be checked, which is troublesome for the user.

The present invention has been made in view of such a conventional problem, and can manufacture a tip pipe at low cost.
It is an object of the present invention to provide a mechanical pencil capable of easily examining and solving a problem even when a problem occurs in a tip pipe such as a clogged core.

[0007]

According to the first aspect of the present invention, there is provided a core feeding mechanism for feeding a core into an outer cylinder, and a leading end opening of the outer cylinder is provided. In a mechanical pencil in which a tip of a tip pipe surrounding a core is protruded, the tip pipe is detachably inserted into and removed from a tip opening of an outer cylinder. Assembly can be performed by inserting the tip pipe into the tip opening of the outer cylinder. Therefore, it can be manufactured and assembled very easily. Since the end pipe can be manufactured separately from the outer cylinder, the yield can be improved. Also, when a problem occurs in the tip pipe, the cause of the defect can be easily investigated by pulling out the tip pipe from the tip opening of the outer cylinder, and if necessary, it can be replaced with another part Becomes

According to a second aspect of the present invention, a friction generating member for generating a frictional force by elastically contacting an inner peripheral surface of an outer cylinder is provided on a rear outer peripheral surface of the tip pipe according to the first aspect. I do. The friction generating member generates friction between the distal end pipe and the outer cylinder, so that the distal end pipe can be prevented from easily coming out of the distal end opening. According to a third aspect of the present invention, the maximum static friction force generated between the outer peripheral surface of the distal end pipe and the inner peripheral surface of the outer cylinder by the friction generating member according to the second aspect is equal to the inner peripheral surface of the distal end pipe. Is larger than the maximum static friction force for holding the core generated between the outer peripheral surface and the outer peripheral surface. Thus, when the wick is fed, the tip pipe does not move relative to the outer cylinder due to the wick, and so-called hiccups of the tip pipe can be prevented.

The invention described in claim 4 is the first to third aspects of the present invention.
The tip pipe according to any one of the above, is formed with a stepped portion that abuts on the end face of the tip opening in order to prevent further entry of the tip pipe into the outer cylinder. In this way, it is possible to prevent a certain amount or more of the distal end pipe from entering the outer cylinder.

[0010] The invention according to claim 5 provides the invention according to claims 1 to 4.
In any one of the above, the position at which the tip pipe has entered the outer cylinder most, when the chuck of the center feeding mechanism disposed in the outer cylinder advances, the chuck pushes the tip pipe. As far as possible, the chuck is at a position where it can contact the rear end of the tip pipe. The tip pipe can be advanced by the chuck, and can be used as a so-called sliding mechanical pencil.

The tip of the tip pipe may have a uniform outer diameter, but the invention according to claim 6 is directed to the tip of the tip pipe according to any one of claims 1 to 5. Have a tapered shape. Due to the tapered shape, it is possible to prevent blind spots from being generated by the tip pipe at the writing destination during writing.

The invention according to claim 7 provides the invention according to claims 1 to 6
5. The frictional force for holding a core generated between an inner peripheral surface of the distal end pipe and an outer peripheral surface of the core, wherein a cut is provided in at least one place of the distal end pipe. Is enhanced. The notch can be used to elastically contact the tip pipe with the core, thereby increasing the core holding force of the tip pipe.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing an embodiment of a mechanical pencil according to the present invention, and FIG. 2 is a sectional view of a main part thereof. In the drawing, reference numeral 10 denotes a mechanical pencil, and the mechanical pencil 10 includes an outer cylinder 12. The outer cylinder 12
Although any configuration can be adopted, this embodiment includes an outer cylinder body 14 and a leading tool 16, and the outer cylinder body 14 and the leading tool 16 are integrally connected to each other by screwing. .

In the outer cylinder 12, a known center feeding mechanism 2 is provided.
0 is provided. The chuck 2 which is capable of reciprocating in the axial direction to tighten the lead 40 and feed the lead 40 by a predetermined amount is provided at the most distal end of the lead sending mechanism 20.
2 are provided. A chuck ring 23 is provided on the outer peripheral side of the chuck 22.

A leading end of a leading end pipe 24 projects from a leading end opening 16a of the leading tool 16. This tip pipe 24
Can be made of metal or resin, and can also be made by combining a plurality of parts instead of an integrated product. A step portion 24 a facing rearward is formed at the tip of the tip pipe 24, and the portion where the step portion 24 a is formed has an outer diameter larger than the inner diameter of the opening of the tip opening 16 a of the leading tool 16. , The end face 16 of the tip opening 16a
b. The step 24a and the tip opening 16a
With the end 16b of the end pipe 24, the tip pipe 24 cannot enter the tip tool 16 any more, in other words,
You cannot retreat.

The portion of the distal end pipe 24 in front of the step surface 24a is a tapered portion 24c whose outer diameter gradually decreases toward the distal end.
At the time of writing, a large blind spot is prevented from being formed by the tip pipe 24 at the writing destination.

The tip of the tip pipe 24 has
The cuts 24d of the book are formed. The cuts 24d, 24d extend in parallel in the axial direction from the tip of the distal end pipe 24, and the two cuts 24d, 24d
The portion sandwiched by d is an elastic piece 24e.

The portion of the tip pipe 24 behind the step portion 24a has an outer diameter smaller than the inner diameter of the opening of the tip opening 16a, and the rear outer peripheral surface of the tip pipe 24 has a further reduced diameter portion 24b. Is formed, and an O-ring 26 is mounted on the outer peripheral surface of the narrowed portion 24b. This O-ring 2
6 is a state in which the end pipe 2 is attached to the throttle section 24b.
4 slightly more radially than the other part of the rear,
It elastically contacts the inner peripheral surface of the leading tool 16 and generates a frictional force with the leading tool 16. By this frictional force, the tip pipe 24
Is movable with respect to the leading tool 16, but its movement is restricted.
4 is held against the leading tool 16.

When the tip pipe 24 constructed as described above is assembled to the tip 16, the tip pipe 24 is not inserted from the rear end of the tip 16, as in the prior art. This can be performed by inserting the tip pipe 24 from the tip opening 16a. Tip pipe 24
As described above, since the rear portion has an outer diameter smaller than the inner diameter of the opening of the distal end opening 16a, the rear portion can pass through the distal end opening 16a. And the step part 24a of the tip pipe 24
When the abutment comes into contact with the end face 16b of the tip opening 16a, the tip pipe 24 can no longer enter the tip tool 16 and the operation is completed. In this manner, very simply, and when the leading tool 16 has already been screwed to the outer cylinder body 14, without disconnecting the connection between the leading tool 16 and the outer cylinder body 14, The work of mounting the tip pipe 24 can be performed. If the tip pipe 24 is found to be defective during an inspection after the assembling operation, the tip pipe 24 is immediately pulled out in the front direction of the tool 16 and a new good tip pipe 24 is removed. Can be replaced.

As described above, since the tip pipe 24 can be detachably inserted into and removed from the tip opening 16a of the tool 16, the tip pipe 24 can be easily attached to the tool 16. On the other hand, once attached, the O-ring 26 attached to the tip pipe 24 generates a frictional force with the tip 16 as described above.
4 cannot move completely freely with respect to the leading tool 16, and its movement is restricted. For example, tip pipe 2
Even when the mechanical pencil 10 is arranged in the vertical direction such that 4 is at the lowermost position, the tip pipe 24 does not escape from the tip opening 16a of the tip 16 and drop due to the weight of the tip pipe 24.

In use, the lead-out mechanism 20 is operated, and when the chuck 22 advances, the chuck elements of the chuck 22 spread radially to release the lead. It is constricted in the inner diameter direction and tightens the core. When the lead is inserted through the chuck 22 in a state where the chuck 22 has released the lead, the lead advances into the distal end pipe 24 and is lightly held by the distal end pipe 24. When the chuck 22 moves forward, the chuck 22 comes into contact with the tip pipe 24,
The tip pipe 24 is pushed forward. As a result, FIG.
The tip pipe 24 protrudes beyond the tip tool 16 to prevent a large blind spot at the writing tip of the core together with the tapered surface 24c.

The elastic piece 24e has a tendency to bend in the inner diameter direction. When the core is inserted through the tip pipe 24, the elastic piece 24e elastically contacts the outer peripheral surface of the core. In order to suppress the core, the frictional force generated between the core and the outer peripheral surface is increased. In this way, the tip pipe 24 can not only protect the outer periphery of the tip of the core, but also hold the core of the tip pipe 24 to some extent. Of course, the core is held between the inner peripheral surface of the distal pipe 24 and the outer peripheral surface of the core without providing the cuts 24d and the elastic pieces 24e so that the inner peripheral surface of the distal end pipe 24 is in sliding contact with the outer peripheral surface of the core. The frictional force for holding the core can be increased by providing the elastic piece 24e in this manner. Therefore, the lead released by the chuck 22 does not fall through the mechanical pencil 10 through the tip pipe 24. Further, even in a state where the lead is shortened and released from the clamping force of the chuck 22, the frictional force for holding the lead of the tip pipe 24 is increased, so that the lead does not rotate or fall off. Can be prevented. The maximum static friction force that can be generated between the tip pipe 24 and the tip tool 16 by the O-ring 26 is the maximum static friction for holding the lead that can be generated between the tip pipe 24 and the lead 40. It is set to be greater than the force. Accordingly, when the chuck 22 reciprocates and sends out the lead, the tip pipe 24 does not move with respect to the tip 16 when the lead attempts to move in response to the movement of the chuck 22, and the tip pipe 24 So-called hiccups can be prevented.

After the writing is completed and the tip pipe 24 and the core are retracted with the chuck 22 released,
The stepped surface 24a is drawn into the leading tool 16 and
In the state of contact with the end face 16b of the front end opening 16a, the drawing limit is reached.

In the case where the wick becomes clogged in the tip pipe 24, the tip pipe 24 is pulled out of the tip 16 as described above, and the wick clogged in the tip pipe 24 is removed. Later, when the tool is inserted again through the leading end opening 16a of the tool 16, the problem can be easily solved.

In the above embodiment, the outer cylinder 12 has been described as being composed of the outer cylinder main body 14 and the leading tool 16, but the invention is not limited to this. Outer cylinder body 1
4 and the tool 16 are integrally formed.
Conventionally, it has been difficult to realize because the distal end pipe 24 cannot be inserted from the rear part of the leading tool 16. However, according to the present invention, the outer cylinder body 14 and the leading tool 16 are integrated. Can also be realized.

In the present embodiment, the center feeding mechanism 2
When the chuck 22 advances at the time of operation 0, the chuck 22 can contact the rear end of the distal pipe 24 so that the chuck 22 can push out the distal pipe 24, and a so-called slide type in which the distal pipe 24 advances during writing. I explained about the mechanical pencil. However, the present invention is not limited to this, and the chuck 22 does not abut on the rear end of the tip pipe 24, and both during writing and during non-writing,
It can be used as a so-called fixed mechanical pencil in which the position of the tip pipe 24 is the same.

[0028]

As described above, according to the present invention,
Since the tip pipe can be put in and taken out from the tip opening of the outer cylinder, the manufacture and assembly of the tip pipe can be performed at low cost, and even when a problem occurs in the tip pipe, the outer pipe can be used. By pulling out from the opening at the front end, the cause of the defect can be easily investigated, and if necessary, it can be replaced with another part.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view illustrating an embodiment of a mechanical pencil of the present invention.

FIG. 2 is a sectional view of a main part of FIG. 1 (a core is omitted).

FIG. 3 is a sectional view of a main part showing a state in which a distal end pipe of FIG. 2 has advanced (a core is omitted).

FIG. 4 is a plan view of a tip pipe.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Mechanical pencil 12 Outer cylinder 16a Tip opening 20 Core feed-out mechanism 22 Chuck 24 Tip pipe 24a Step surface 24c Taper part 24d Cut 26 O-ring (friction generating member)

Claims (7)

[Claims] 1. A mechanical pencil, wherein a lead sending mechanism for sending a lead into an outer cylinder is provided, and a tip end of a tip pipe surrounding the lead projects from a tip opening of the outer cylinder. A mechanical pencil characterized in that it can be inserted and removed from the opening at the tip of the outer cylinder. 2. A mechanical pencil according to claim 1, wherein a friction generating member is provided on an outer peripheral surface of a rear portion of the tip pipe so as to elastically contact an inner peripheral surface of the outer cylinder to generate a frictional force. 3. The maximum static friction force generated between the outer peripheral surface of the tip pipe and the inner peripheral surface of the outer cylinder by the friction generating member is generated between the inner peripheral surface of the tip pipe and the outer peripheral surface of the core. 3. The mechanical pencil according to claim 2, wherein the mechanical force is larger than a maximum static friction force for holding the lead. 4. The end pipe is formed with a step which abuts on an end face of a tip opening to prevent the tip pipe from entering the outer cylinder any more. 4. The mechanical pencil according to any one of items 3 to 3. 5. The position where the tip pipe has entered the outer cylinder most is set so that the chuck can push out the tip pipe when the chuck of the center feeding mechanism disposed in the outer cylinder advances. The mechanical pencil according to any one of claims 1 to 4, wherein is a position capable of contacting a rear end of the front end pipe. 6. The mechanical pencil according to claim 1, wherein a distal end of the distal end pipe is tapered. 7. A notch is provided in at least one portion of the tip pipe to increase a frictional force generated between the inner peripheral surface of the tip pipe and the outer peripheral surface of the core for holding the core. 7. The method according to claim 1, wherein:
The mechanical pencil described in the item.