JP6925925B2 - mechanical pencil - Google Patents

Description

The present invention relates to a mechanical pencil used in a state in which a writing core housed inside a shaft cylinder is extended from the shaft cylinder and protrudes from a tip portion.

In a mechanical pencil that is used by projecting the front end of the writing core from the tip of the barrel, the longer the front end of the writing core that protrudes from the tip of the barrel, or the higher the writing pressure, the more the shaft. There is a problem that the front end of the writing core protruding from the tip of the cylinder is burdened and easily broken.
Mechanical pencils that try to solve this problem are described in, for example, Patent Documents 1 to 3.

In Patent Document 1, when an excessive writing pressure is applied to the writing core sandwiched between the chucks in the rear along the axis of the shaft cylinder, the pressing pressure is applied by a buffer spring arranged in the shaft cylinder. A mechanical pencil with a structure that cushions and prevents core breakage is described.
In this structure, the cushioning spring that expands and contracts in the direction along the axis functions effectively against the writing pressure when writing with the mechanical pencil barrel upright, but in general, the user is on the paper surface. On the other hand, since the writing is done by tilting the shaft tube, the cushioning spring does not function effectively, and it may not be possible to prevent the core from breaking. In particular, when writing is performed by tilting the shaft tube, a writing pressure is applied to the writing core at an angle to the axis of the shaft cylinder. Therefore, a thin lead of a mechanical pencil has a large load, which is the structure of Patent Document 1. However, the problem of broken core is likely to occur.

In Patent Document 2, when an excessive writing pressure is applied to the writing core in the rear along the axis, the writing core is protected by being immersed in the holder as in Patent Document 1, and the shaft cylinder is used. When writing is performed at an angle to the paper surface and an oblique writing pressure is applied to the writing core sandwiched between the chucks with respect to the axis of the shaft, the holder moves to the front of the shaft to protect the writing core. A mechanical pencil with a structure to be used is described.
This structure takes into consideration the breakage of the lead when writing with the barrel tilted, but as described in Patent Document 2, the number of parts is large and the structure is complicated. , There is a problem that it is difficult to adopt it for low-priced mechanical pencils.

In Patent Document 3, a protruding portion is formed at the tip of a tip member having a passage for the writing core, and by providing a weight portion on the tip member, the writing core is written in a state where the barrel is slanted. Described is a mechanical pencil having a structure in which the tip member is rotated by gravity when abutting against a surface so that the protruding portion is located on the upper surface of the outer peripheral surface of the writing core 5.
Since this structure has a simple structure, it can be widely applied from low-priced to high-priced mechanical pencils, but since the weight part is arranged in front of the barrel, it affects the writing feeling. There is a risk that it will end up.

Jikkai Sho 56-130874 Japanese Unexamined Patent Publication No. 2015-123689 JP-A-2017-140808

The present invention has been made in view of the above problems, and a mechanical pencil capable of preventing core breakage when writing is performed by tilting the barrel, which causes a large load on the writing core, is provided. The purpose is to obtain it with a simple configuration.

The present invention
"1. Inside the shaft tube,
A core feeding unit that feeds out the writing core,
A tip member having a passage through which the writing core passes, and
A ring-shaped rotating body having a through hole through which the tip member is inserted and rotatably held in a receiving portion provided on the shaft cylinder is arranged.
By shifting the center of the through hole of the rotating body from the center of the rotating body, a change in wall thickness in the radial direction is formed in the rotating body.
A protrusion covering a part of the side surface of the writing core is provided at the front end of the tip member.
The protruding portion of the front end member is positioned on the thinnest wall side formed between the through hole of the rotating body and the outer surface of the rotating body.
When the writing core is brought into contact with the writing surface in a state where the barrel is slanted, the tip member is rotated by the writing pressure, and the protruding portion is located on the upper surface of the outer periphery of the writing core. A mechanical pencil featuring.
2. A protrusion for restricting mutual rotation is provided in a portion adjacent to the tip member and the through hole of the rotating body.
The tip member is inserted into the through hole of the rotating body so as to be movable back and forth.
The mechanical pencil according to item 1, wherein the front opening member retracts to the rear of the barrel as the writing core is worn by writing. ".

In the mechanical pencil according to the present invention, when a writing pressure diagonally applied to the writing core with respect to the axis of the barrel is applied, the protruding portion provided at the front end of the tip member is located on the upper surface of the outer periphery of the writing core. It is possible to prevent the writing core from being deformed upward and prevent the core from breaking.

The shape of the rotating body is not limited, but when the shaft cylinder is cylindrical, the outer diameter of the rotating body can be set to the inner diameter of the shaft cylinder even in a narrow shaft cylinder by forming it in an annular shape according to the shaft cylinder. By combining them, it is possible to form a large body, and the writing pressure is easily applied to the rotating body, so that the rotating body is easily rotated.

The receiving portion of the shaft cylinder that holds the rotating body may be formed according to the outer shape of the rotating body. The rotating body may be in contact with a plurality of points such as two points or three points with respect to the receiving portion of the barrel, but the structure is such that stable rotation is possible by contacting the rotating body over the entire circumference.
As an example, there is a structure in which a circular large-diameter portion formed on the outer surface of a rotating body is engaged with a circular receiving portion formed on the inner surface of the barrel so as to slide.
In order to smooth the rotation of the rotating body with respect to the receiving portion of the shaft cylinder, the rotating body or the receiving portion of the shaft cylinder may be made of a resin material such as fluororesin having excellent slidability, or the rotating body and the receiving portion may be formed. Grease or oil can be applied between the parts, or a structure such as a ball bearing can be used to improve the rotatability.

By configuring the tip member so that it can be displaced in the radial direction together with the feeding unit, a load acting in the radial direction is applied to the writing core in a state of being sandwiched between the chucks of the feeding unit and inserted into the passage of the front opening. Since it disappears, it is possible to prevent the core from breaking.
As an example, there is a structure in which the outer peripheral surface in front of the feeding unit is attached so as to be in sliding contact with the inner peripheral surface of the front opening member.
Further, the shape of the protruding portion formed at the front end of the tip member is not limited, but when writing pressure is applied, the inner surface of the protruding portion comes into contact with a part of the outer surface of the writing core. In order to prevent the core from breaking, it is preferable to make the inner surface of the protruding portion continuous with the passage so that the inner surface in contact with the writing core is not stepped.

Furthermore, by allowing the tip member to move backward with respect to the barrel, even when the writing core is worn by writing, when the front end of the tip member and the front end of the writing core are aligned, The front end member whose protruding portion is in contact with the writing surface is retracted, so that continuous writing can be performed, and convenience can be improved.
In this case, it is located on the opposite side of the protruding portion at the front end of the front end member, that is, when the writing core is brought into contact with the writing surface with the barrel tilted, it is located below the outer peripheral surface of the writing core. Since the rearmost end of the front end edge is located behind the protruding portion, even if the tip of the writing core is worn, the tip member has a structure that makes it difficult for the tip member to come into contact with the writing surface such as the paper surface, making writing easier. Become.

Since the operation of feeding out the writing core is often performed when the barrel is tilted and viewed from the side, it is necessary to prevent the protruding portion of the tip member from covering the outer peripheral surface of the writing core too much. There is.
For example, in the case where the writing core is connected from the base where the writing core is exposed for a long time (position opposite to the axis of the protrusion) to the tip of the protrusion at an oblique edge, the user The feeding operation is performed by paying attention to the protrusion amount of the writing core on the base side that comes into contact with the writing surface most, and as a result, the protrusion amount of the writing core on the protrusion side from the tip of the protrusion is shortened. The structure prevents core breakage.
On the other hand, in the form in which the protruding portion covers the writing core too much, the user pays attention to the length from the tip of the protruding portion, not the base side, as the criterion for determining the amount of protrusion when the writing core is extended. As a result, it becomes difficult to prevent the core from breaking.

In the present invention, it is possible to obtain a mechanical pencil having a simple configuration, which can prevent the lead from breaking when writing is performed by tilting the barrel, which causes a large load on the writing lead.

It is a vertical sectional view of the mechanical pencil of this embodiment. It is sectional drawing of the main part of the mechanical pencil of this embodiment. It is sectional drawing of the main part which shows the state of writing with the mechanical pencil of this embodiment.

In the description of this embodiment, the side in which the writing core protrudes is expressed as the front side, and the opposite side is expressed as the rear side. For the sake of clarity, similar members and similar parts in the drawings are designated by the same reference numerals.

Hereinafter, the mechanical pencil of this embodiment will be described with reference to FIGS. 1 to 3.
The shaft cylinder 2 of the mechanical pencil 1 has a shaft cylinder main body 3 and a base 4 bonded to the front of the shaft cylinder main body 3.

The axle cylinder main body 3 is formed by screwing a front shaft 31 and a rear shaft 32, and a core feeding unit 7 having a chuck 6 for feeding the writing core 5 is housed therein. A tip member 8 having a passage 8a of the writing core 5 is mounted inside the mouthpiece 4 which is in front of the writing core 7.
The front opening member 8 of this embodiment is rotatably mounted inside the barrel 2, and is retractable with respect to the barrel 2 by providing a space behind the barrel 2.

The core feeding unit 7 operates via the core tank 9 connected to the knock body 33 by pushing the knock body 33 protruding from the rear end of the barrel main body 3. The core tank 9 is connected to a chuck 6 that sandwiches the writing core 5 via a tubular connecting body 10 in which the front portion 9a of the core tank 9 is inserted into the rear portion 10a, and the chuck 6 is a knock body. It is designed to follow the back-and-forth movement of 33 and the core tank 9.

The connecting body 10 has a front portion 10b inserted through an opening 11b of a hollow cylindrical member 11 having an inner stage 11a formed at a front end thereof. A chuck spring 12 is arranged between the inner stage 11a of the cylindrical member 11 and the front end of the connecting body 10, and the connecting body 10 is elastically repelled by the chuck spring 12 in contact with the inner stage 11a of the cylindrical member 11. The head portion 6b of the chuck 6 whose rear end portion 6a is fitted into the opening portion 10c of the connecting body 10 is fastened with a tightening ring 13 which is in contact with the inner stage 11a of the cylindrical member 11, and the writing core 5 is written. It is sandwiched so that it does not recede due to pressure. In the chuck 6 of this embodiment, the head portion 6b is divided into three so that the writing core 5 can be sandwiched.

When the front end portion 5a of the writing core 5 consumed by writing is projected from the front end opening 8b of the front opening member 8, the connecting body 10 and the chuck 6 are advanced by the core tank 9 which is advanced by pushing the knock body 33. The chuck 6 is closed until the tightening ring 13 externally fitted to the head portion 6b of the chuck 6 comes into contact with the inner flange 14a provided on the front inner surface of the inner tip opening 14 arranged inside the barrel main body 3 to open the chuck 6. 6 allows the writing core 5 to move forward so that the front end portion 5a of the writing core 5 can be projected from the front end opening 8b of the front opening member 8.

The advance of the chuck 6 is restricted by the head portion 6b of the chuck 6 coming into contact with the inner flange 14a of the inner tip opening 14, and when the pushing of the knock body is stopped after the writing core 5 is extended, the chuck spring 12 The connecting body 10 and the chuck 6 are retracted due to the elastic force of the above, but the writing core 5 is a core attached to the inside of the tip member 8 until the tightening ring 13 tightens the head portion 6b of the chuck 6 again. Since it is held by the holder 15, the front end portion 5a of the writing core 5 can be maintained in a state of protruding from the front end opening 8b of the front opening member 8.

Next, the tip member 8 will be described in detail with reference to FIG.
The front end member 8 is an intermediate portion located between the front portion 8c protruding from the front end of the mouthpiece 4, the rear portion 8e housed inside the barrel main body 3, and the front portion 8c and the rear portion 8e. It has 8d, and its outer diameter is defined as front portion 8c <intermediate portion 8d <rear portion 8e.

The intermediate portion 8d of the front opening member 8 is inserted into the through hole 16a of the ring-shaped rotating body 16 arranged inside the mouthpiece 4 so as to be movable back and forth, and is inserted into the intermediate portion 8d of the front opening member 8. The fitted protrusion 81 is locked in the key groove 16b formed in the through hole 16a of the rotating body 16 and extending in the front-rear direction so that the front end member 8 does not rotate with respect to the rotating body 16.

A large-diameter portion 16c is formed in front of the rotating body 16, and the large-diameter portion 16c is arranged inside a receiving portion 4b formed by providing an inner stage 4a on the inner surface of the base 4, and has a large diameter. The front end surface of the portion 16c abuts on the inner stage 4a of the recess 4b, and the rear end surface of the large diameter portion 16c abuts on the tip 3a of the barrel body 3, thereby restricting the movement of the rotating body 16 in the front-rear direction. ..

Since the through hole 16a of the ring-shaped rotating body 16 is circular and the center of the through hole 16a is offset from the center of the rotating body 16, the wall thickness of the rotating body 16 changes in the radial direction. .. The key groove 16b is formed in the thickest maximum wall thickness portion 16d of the rotating body 16, and the thinnest minimum wall thickness portion 16e of the rotating body 16 is located on the opposite side thereof.

The front end of the front end portion 8c of the front opening member 8 of the present embodiment is a protruding portion 8f that is obliquely inclined toward the front, and the front end portion 8g of the protruding portion 8f is a protrusion provided on the intermediate portion 8d in the radial direction. It is formed on the opposite side of the body 81. The front end portion 8g is located 1 mm forward in the axial direction with respect to the base portion 8h of the protruding portion 8f.

Next, the operation of the mechanical pencil 1 at the time of writing will be described with reference to FIG.
In the mechanical pencil 1 of the present embodiment, the writing core 5 is brought into contact with the writing surface S in a state where the shaft cylinder is slanted, and the force F generated by the writing pressure is passed through the writing core 5 to the tip member 8 A cam action is generated by being transmitted to the front portion 8c of the above, and the minimum thin portion 16e is located on the upper side of the barrel 2 (above the writing surface S) in the writing state while the ring-shaped rotating body 16 rotates. At the same time, the front end portion 8g of the front end member 8 is arranged on the upper side of the shaft cylinder 2.
As a result, the writing core 5 can receive the upward force due to the writing pressure on the inner surface of the front end portion 8g of the tip member 8, and can prevent the writing core 5 from breaking due to the writing pressure, and at the time of writing. Since the lower surface connecting the front end portion 8g and the base portion 8h located below is inclined toward the writing surface S, the inclined protrusion even when writing is continued in the state of FIG. The distance until the portion 8f comes into contact with the writing surface S becomes long, and as a result, the distance that can be continuously written becomes long.

Furthermore, in the mechanical pencil 1 of the present embodiment, since the tip member 8 can be retracted, the writing core 5 is worn along with writing and the front portion 8c of the tip member 8 is retracted, so that the lead member 8 is frequently retracted. It is possible to write for a long time without paying out, which enables continuous writing until the rear end of the front opening member 8 abuts on the outer stage 14b of the inner front opening 14.
The mechanical pencil 1 of the present embodiment is designed so that the outer peripheral surface 14c of the inner front opening 14 can be slidably contacted with the inner peripheral surface 8h of the front opening member 8 when the rotating body 16 rotates. Since the inner tip 14 and the lead feeding unit 7 are driven, the writing lead 5 located between the passage 8a of the tip member 8 and the chuck 6 is not loaded, and the lead is broken in the barrel 2. Can be prevented.

1 ... Mechanical pencil,
2 ... Shaft tube,
3 ... Shaft cylinder body, 3a ... Tip, 31 ... Front shaft, 32 ... Rear shaft, 33 ... Knock body,
4 ... Mouthpiece, 4a ... Inner stage, 4b ... Receiving part,
5 ... Writing core, 5a ... Front end,
6 ... Chuck, 6a ... Rear end, 6b ... Head,
7 ... Core feeding unit,
8 ... Front opening member, 8a ... Passage, 8b ... Front end opening, 8c ... Front part, 8d ... Middle part, 8e ... Rear part, 8f ... Protruding part, 8g ... Front end part, 8h ... Base part, 8i ... Inner peripheral surface, 81 ... protrusion,
9 ... core tank, 9a ... front part,
10 ... Connecting body, 10a ... Rear part, 10b ... Front part, 10c ... Opening,
11 ... Cylindrical member, 11a ... Inner stage, 11b ... Opening,
12 ... Chuck spring,
13 ... Tightening ring,
14 ... Inner tip, 14a ... Inner collar, 14b ... Outer stage, 14c ... Outer surface,
15 ... wick holder,
16 ... Rotating body, 16a ... Through hole, 16b ... Key groove, 16c ... Large diameter part, 16d ... Maximum wall thickness part, 16e ... Minimum wall thickness part.

Claims (2)

Inside the barrel,
A core feeding unit that feeds out the writing core,
A tip member having a passage through which the writing core passes, and
A ring-shaped rotating body having a through hole through which the tip member is inserted and rotatably held in a receiving portion provided on the shaft cylinder is arranged.
By shifting the center of the through hole of the rotating body from the center of the rotating body, a change in wall thickness in the radial direction is formed in the rotating body.
A protrusion covering a part of the side surface of the writing core is provided at the front end of the tip member.
The protruding portion of the front end member is positioned on the thinnest wall side formed between the through hole of the rotating body and the outer surface of the rotating body.
When the writing core is brought into contact with the writing surface in a state where the barrel is slanted, the tip member is rotated by the writing pressure, and the protruding portion is located on the upper surface of the outer periphery of the writing core. A mechanical pencil featuring. A protrusion for restricting mutual rotation is provided in a portion adjacent to the tip member and the through hole of the rotating body.
The tip member is inserted into the through hole of the rotating body so as to be movable back and forth.
The mechanical pencil according to claim 1, wherein the front opening member retracts to the rear of the barrel as the writing core is worn by writing.

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