JP2022002892A - Automatic delivery type mechanical pencil and manufacturing method for protector for automatic delivery type mechanical pencil - Google Patents

Abstract

To reduce amounts of a lead which is wasted.SOLUTION: An automatic delivery type mechanical pencil 1 according to the present invention comprises: a metallic lead protector 20 formed by squeezing processing to have a narrowed part 20b at a front end thereof and configured to be movable along a pen holder direction; a cylindrical lead-conveying grip 22 inserted into a relatively front position inside the lead protector 20 and having an outer diameter larger than an inner diameter R5 of the narrowed part 20b; a cylindrical bracket 21 inserted into a relatively rear position inside the lead protector 20 and fixed to the lead protector 20; a coil spring that energizes the lead protector 20 forward a front side; and a chuck mechanism configured to be movable along the pen holder direction and having a lead fixing grip that grips a rear part of the lead inserted into the lead protector 20 when retreating and releases the lead when advancing.SELECTED DRAWING: Figure 5

Description

The present invention relates to an automatic pay-out type mechanical pencil and a method for manufacturing a lead protector for an automatic pay-out type mechanical pencil.

In recent years, automatic draw-out mechanical pencils that do not require knock operation, such as Pilot Corporation's Automac (registered trademark), Pentel Co., Ltd.'s Orensnero (registered trademark), and Auto Co., Ltd.'s Noknock (registered trademark), have attracted attention. There is. Patent Document 1 discloses a specific configuration example of this type of mechanical pencil. As described in the same document, the automatic pay-out mechanical pencil is described as a core protector (in Patent Document 1, "slider (4)") arranged on the pen tip in a state of being slidable in the axial direction. Hereinafter, the description in parentheses in this paragraph indicates the name in Patent Document 1 having the corresponding configuration), the lead transfer grip (elastic piece (6)) fixed to the rear end of the lead protector, and the casing. A chuck mechanism (chuck (13)) arranged inside the body, a spring (spring (27)) provided between the core protector and the chuck mechanism, and a chuck ball (ball (15)) that urges the chuck mechanism in the radial direction. ) And. In this specification, it is assumed that the pen tip side of the mechanical pencil is "front" and the end side is "rear".

While writing with writing pressure, the chuck mechanism is in a retracted state due to the elastic force of the spring, and the core is strongly pinched by the action of the chuck ball. Therefore, writing can be performed without the core moving backward due to the writing pressure. When the pen tip is raised from the writing surface and the writing pressure becomes zero, the core protector moves forward due to the urging force of the spring, but at this time, since the core transport grip grips the core, the core also moves forward. .. Further, the chuck mechanism also moves forward by being pulled by the core that moves forward, and the gripping action of the chuck ball is released. As a result, the wick can move forward without being disturbed by the chuck mechanism. In this way, the core is automatically extended without knocking.

Japanese Unexamined Patent Publication No. 62-035896

By the way, according to the configuration example of the automatic pay-out type mechanical pencil described above, if the length of the lead becomes shorter with writing and the trailing end does not reach the chuck mechanism, the lead cannot be advanced in principle. , I can't continue writing. In this regard, if the next core is supplied into the chuck mechanism, the rear end of the previous core can be supported by the tip of the next core, so that it is considered that writing can be continued. However, if the tip core becomes even shorter and its length is shorter than the distance between the pen tip and the core transfer grip, the tip core will not be gripped by anything and the pen tip will point downwards. If you do, it will fall out of the core protector. As a result, a core having a length almost equal to the total length of the core protector is wasted.

Therefore, one of the objects of the present invention is to provide an automatic pay-out type mechanical pencil that can reduce the amount of wasted lead.

Further, even if the next core is supplied into the chuck mechanism, the rear end of the previous core is not always supported by the tip of the next core. This is because the rear end of the previous core and the tip of the next core come into contact with each other in the air, so that the contact cannot be made stably. In the worst case, each core can be shattered.

In addition, if the tip of the next wick cannot support the rear end of the previous wick, then the wick gripped by the wick transport grip must be pulled out in order to utilize the next wick. Since the gripping force of the core transport grip is fairly strong, it is necessary to apply a certain amount of force when pulling it out, and the hands become dirty.

Therefore, another object of the present invention is to provide an automatic payout mechanical pencil in which the rear end of the previous core is supported by the tip of the next core.

Further, in order to reduce the amount of wasted core, it is conceivable to provide a configuration corresponding to the core transport grip inside the core protector, but for that purpose, the core transport grip is prevented from falling to the front end of the core protector. It is necessary to provide a stenosis for this. However, in order to achieve good writing quality, it is possible to form the core protector in a cylindrical shape as thin as possible (typically, the outer diameter is about 0.74 mm) and then form a smaller constriction at the tip. It was impossible in the past.

Therefore, another object of the present invention is an automatic pay-out mechanical pencil capable of forming a constricted portion at the tip of the lead protector to prevent the lead transfer grip from falling while ensuring good writing quality. To provide a method for manufacturing a lead protector for a pencil.

The automatic pay-out mechanical pencil according to the first aspect of the present invention is a metal lead protector formed by drawing so as to have a narrowed portion at the front end and is movable along the pen axial direction. , A tubular core transfer grip that is inserted at a position relatively forward inside the core protector and has an outer diameter larger than the inner diameter of the constricted portion, and a relatively rearward position inside the core protector. A tubular bracket that is inserted in the position and fixed to the lead protector, a coil spring that urges the lead protector forward, and a coil spring that can be moved along the pen axis direction, and the lead protector when retracted. It is an automatic mechanical pencil equipped with a chuck mechanism having a core fixing grip that releases the core when moving forward while holding the rear portion of the core inserted inside.

The automatic pay-out type mechanical pencil according to the second aspect of the present invention is a mechanical pencil according to the first aspect of the present invention in which the coil spring is composed of a wire having a rectangular cross section.

The method for manufacturing a lead protector for an automatic mechanical pencil according to the third aspect of the present invention is a step of forming a cylindrical protruding portion on a metal blank by drawing, and a bottom surface of the protruding portion by drilling. In addition, a step of forming a hole having a diameter smaller than the inner diameter of the protruding portion and a pen tip of an automatic mechanical pencil by separating the protruding portion from the blank by trimming the blank while leaving a flange. It is a manufacturing method of a lead protector for an automatic pay-out type mechanical pencil including a step of acquiring a lead protector to be configured.

According to the first aspect of the present invention, since the core transport grip can be provided near the tip of the core protector, it is possible to reduce the amount of wasted core.

According to the second aspect of the present invention, by making the inner diameter of the coil spring substantially equal to the diameter of the core, it is possible to prevent the end of the core from floating in the air even at the spring portion. The tip of the wick makes it possible to support the rear end of the wick.

According to the third aspect of the present invention, the core protector is manufactured by drawing processing capable of forming an ultra-fine (typically, an outer diameter of about 0.74 mm) bottomed cylinder, so that good writing quality is ensured. At the same time, it becomes possible to form a narrowed portion at the tip of the core protector to prevent the core transport grip from falling.

It is sectional drawing of the mechanical pencil 1 when the operation lever 10 is set in the pen tip storage position. It is an enlarged view of the tip part of the mechanical pencil 1 shown in FIG. It is a top view of the unit positioning lever 11 shown in FIG. 2A and 2B are views for explaining the operation of the core fixing grip 12 shown in FIG. 2, and are bottom views and cross-sectional views when the lower surface of the core fixing grip 12 is separated from the stopper 15, respectively. c) and (d) are a bottom view and a cross-sectional view when the lower surface of the core fixing grip 12 is in contact with the stopper 15, respectively. It is an enlarged view of the tip member 9 shown in FIG. It is an enlarged view of the tip part of the mechanical pencil 1 when the operation lever 10 is set in the writing possible position. It is an enlarged view of the tip part of the mechanical pencil 1 when the operation lever 10 is moved to the core replenishment position from the state of FIG. It is an enlarged view of the tip part of the mechanical pencil 1 when the operation lever 10 is returned to the writing possible position from the state of FIG. FIG. 8 is an enlarged view of a tip portion of a mechanical pencil 1 when writing is started by bringing the pen tip into contact with the writing surface S in the state of FIG. 8. 9 is an enlarged view of the tip portion of the mechanical pencil 1 when the pen tip is separated from the writing surface S in the state of FIG. 9. It is an enlarged view of the tip portion of the mechanical pencil 1 in the case where writing is continued and the lead L is shortened and only a small part of the rear end is sandwiched by the lead fixing grip 12. 11 is an enlarged view of the tip portion of the mechanical pencil 1 when the pen tip is separated from the writing surface S in the state of FIG. 11. 11 is an enlarged view of the tip of the mechanical pencil 1 when the next lead L is present in the replacement lead stocker 5 when the pen tip is separated from the writing surface S in the state of FIG. 11. FIG. 13 is an enlarged view of a tip portion of a mechanical pencil 1 when writing is continued with the pen tip in contact with the writing surface S in the state of FIG. 13. FIG. 14 is an enlarged view of a tip portion of a mechanical pencil 1 when the pen tip is separated from the writing surface S after writing in the state of FIG. 14. FIG. 15 is an enlarged view of the tip portion of the mechanical pencil 1 when the operating lever 10 is set at the core replenishment position in the state of FIG. It is a flow chart which shows the manufacturing process of a core protector 20.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1A is a cross-sectional view of a mechanical pencil 1 according to an embodiment of the present invention. Further, FIG. 2 is an enlarged view of a tip portion of the mechanical pencil 1 shown in FIG. As shown in these figures, the mechanical pencil 1 has a housing 2, a tip bracket 3, an eraser fixing bracket 4, a replacement core stocker 5, a chuck mechanism 6, a coil spring 7, a bracket 8, and a tip member 9. It is composed of.

The housing 2 is a substantially cylindrical member constituting the main body of the mechanical pencil 1, and is typically formed by using a lightweight material such as an aluminum alloy or a resin molded product. However, in order to produce a sense of quality, the housing 2 may be configured using a heavier material. The inside of the housing 2 penetrates from the front end to the rear end, and constitutes the first hollow portion 2a, the second hollow portion 2b, and the third hollow portion 2c in order from the rear end side. The first hollow portion 2a, the second hollow portion 2b, and the third hollow portion 2c are all cylindrical spaces having the pen axis as the cylindrical axis, and the diameter of the second hollow portion 2b is the first. It is smaller than the diameter of the hollow portion 2a and the third hollow portion 2c. The housing 2 further has a recess 2d on the side surface for accommodating the operation lever 10 described later. A rectangular through hole 2e having a long axis in the pen axis direction is provided in a part of the bottom surface of the recess 2d, and the recess 2d and the second hollow portion 2b communicate with each other through the through hole 2e. ..

An eraser fixing bracket 4 for gripping the cylindrical eraser E is fixed in the first hollow portion 2a. Although not shown, a head cap covering the eraser E may be provided at the rear end of the mechanical pencil 1. The gripping force of the eraser fixing bracket 4 is set to such a force that the eraser E can be easily pulled out by human power while the eraser E can be prevented from falling off naturally. One end of the core clogging release bar R is inserted into the lower part of the eraser E. The core clogging release bar R is a needle-shaped member having a diameter slightly thinner than the core L used in the mechanical pencil 1. An annular portion is provided in the middle of the core clogging release bar R, and by embedding this annular portion in the eraser E, the core jam release bar R is prevented from falling off from the eraser E. The core clogging release bar R is for clearing the clogging by inserting the other end of the core clogging release bar R into the tip member 9 removed from the housing 2 when the core L is clogged in the tip member 9. Used for.

In the second hollow portion 2b, a replacement core stocker 5 and a part of the chuck mechanism 6, which are substantially tubular members configured to accommodate a plurality of cores L, can be moved in the pen axis direction, respectively. Is inserted with. The replacement core stocker 5 is typically a substantially cylindrical member made of a lightweight metal material such as an aluminum alloy. The outer diameter of the replacement core stocker 5 is set to be slightly smaller than the inner diameter of the second hollow portion 2b, whereby the replacement core stocker 5 moves in the second hollow portion 2b in the pen axis direction without shaking. It is configured to be possible. The inside of the replacement core stocker 5 penetrates from the front end to the rear end, and constitutes the first hollow portion 5a, the second hollow portion 5b, and the third hollow portion 5c in order from the rear end side. The first hollow portion 5a, the second hollow portion 5b, and the third hollow portion 5c are all cylindrical spaces having the pen axis as the cylindrical axis, and the diameter of the second hollow portion 5b is the first. It is smaller than the diameter of the hollow portion 5a and the third hollow portion 5c.

The diameter of the first hollow portion 5a is set to a value that allows a plurality of cores L to be arranged and stored in the radial direction. The rear end of the first hollow portion 5a communicates with the first hollow portion 2a, and when the eraser E is removed, a plurality of cores L can be inserted through the first hollow portion 2a. The first hollow portion 5a also serves to accommodate the other end of the core clogging release bar R. The diameter of the second hollow portion 5b is set to a value that allows one core L to pass through without resistance, while a plurality of cores L cannot pass through. The rear end of the second hollow portion 5b communicates with the first hollow portion 5a, and is configured to receive only one core L from the first hollow portion 5a at the same time. The third hollow portion 5c communicates with the front end of the second hollow portion 5b. A convex portion 12a provided at the rear end of the core fixing grip 12, which will be described later, is fixed to the third hollow portion 5c by screwing.

Focusing again on the housing 2, the convex portion 3a provided at the rear end of the tip bracket 3 is detachably fitted and fixed to the third hollow portion 2c. The tip bracket 3 is a member that constitutes the periphery of the pen tip of the mechanical pencil 1. The inside of the tip bracket 3 penetrates from the front end to the rear end, and as shown in FIG. 2, the first hollow portion 3b, the second hollow portion 3c, and the third hollow portion 3d are sequentially formed from the rear end side. It is composed. The first hollow portion 3b, the second hollow portion 3c, and the third hollow portion 3d are all cylindrical spaces having the pen axis as the cylindrical axis, and the diameter of the first hollow portion 3b is the second. The diameter of the second hollow portion 3c is larger than the diameter of the hollow portion 3c, and the diameter of the second hollow portion 3c is larger than the diameter of the third hollow portion 3d.

The first hollow portion 3b has a diameter substantially equal to that of the second hollow portion 2b. However, the foremost end portion of the first hollow portion 3b is formed with a diameter slightly smaller than that of the other portions. This is because when the stopper 15 described later is located at the foremost end of the first hollow portion 3b as a result of the operation of the operation lever 10 described later, the coil is fitted by the fitting of the first hollow portion 3b and the stopper 15. This is to prevent the stopper 15 from moving due to the elastic force of the spring 7. Therefore, the gripping force due to this fitting is set to a value larger than the elastic force of the coil spring 7. The gripping force due to this fitting also needs to be weaker than the adhesive force between the stopper 15 and the cam bracket 14, which will be described later.

The rear end of the first hollow portion 3b communicates with the second hollow portion 2b, and a part of the chuck mechanism 6 and a part of the coil spring 7 are inserted in a state where they can move in the pen axis direction. The rear end of the second hollow portion 3c communicates with the first hollow portion 3b. A part or all of the coil spring 7, the bracket 8, and a part of the tip member 9 are inserted into the second hollow portion 3c in a state where they can be moved in the pen axis direction. The rear end of the third hollow portion 3d communicates with the second hollow portion 3c. A part of the tip member 9 is inserted into the third hollow portion 3d in a state where it can be moved in the pen axis direction. The diameter of the third hollow portion 3d is smaller than the flange 20a described later included in the tip member 9, and therefore, the step formed at the boundary between the third hollow portion 3d and the second hollow portion 3c is the step of the tip member 9. It plays a role in preventing falling out.

Next, as shown in FIGS. 1 and 2, the chuck mechanism 6 includes an operation lever 10, a unit positioning lever 11, a core fixing grip 12, a coil spring 13, a cam bracket 14, and a stopper 15.

The operating lever 10 is a member formed of a lightweight metal material such as an aluminum alloy, and is fitted into the recess 2d of the housing 2 in a state of being movable in the pen axis direction. The surface of the operating lever 10 is exposed to the outside of the housing 2, and the user can operate the operating lever 10.

Two recesses 10a and 10b are provided on the bottom surface of the operating lever 10 (the surface located inside the housing 2). Of these, the coil spring 10c, the plate-shaped body 10d, and the unit positioning R ball 10e are arranged in this recess 10a in order from the back side. On the other hand, the protrusion 11b of the unit positioning lever 11, which will be described later, is inserted into the recess 10b with a certain amount of play in the pen axis direction.

The unit positioning R ball 10e and the plate-shaped body 10d are members formed by using a lightweight metal material such as an aluminum alloy, and are configured to be movable in the depth direction of the recess 10a. The coil spring 10c is, for example, a spring composed of a round wire coil, and serves to urge the unit positioning R ball 10e outward via the plate-shaped body 10d. Since this urging force plays a role of locking the position of the operating lever 10, it is preferable to use a spring having a slightly strong elastic force as the coil spring 10c.

The unit positioning lever 11 is a member that plays a role of transmitting the movement of the operating lever 10 to the core fixing grip 12, and is typically formed by using a lightweight metal material such as an aluminum alloy.

FIG. 3 is a top view of the unit positioning lever 11. As shown in the figure, the unit positioning lever 11 has a structure in which a protrusion 11b is provided in a circular portion having an opening 11a in the center. The convex portion 12a of the core fixing grip 12 is fitted into the opening 11a. As described above, since the tip of the convex portion 12a is screwed with the third hollow portion 5c, the unit positioning lever 11 is fixed in a state of being sandwiched between the core fixing grip 12 and the replacement core stocker 5. Will be.

Further, the protrusion 11b is inserted into the recess 10b provided on the bottom surface of the operating lever 10 through the through hole 2e shown in FIG. As described above, the through hole 2e is a rectangular hole having a long axis in the pen axis direction, and the inner wall in the short axis direction prohibits the movement of the protrusion 11b in the circumferential direction (that is, the rotation of the unit positioning lever 11). At the same time, the inner wall in the long axis direction plays a role of restricting the movement of the unit positioning lever 11 in the pen axis direction within a certain range. Along with this, the movement of the replacement core stocker 5 fixed to the unit positioning lever 11 is also restricted, so that the replacement core stocker 5 is prevented from falling off from the mechanical pencil 1.

Returning to FIG. 2, the width of the recess 10b in the pen axis direction is set to be slightly larger than the width of the protrusion 11b in the pen axis direction, whereby a certain amount of play in the pen axis direction is set between the protrusion 11b and the recess 10b. Has occurred. As will be described in detail later, this play is provided so that the core fixing grip 12 pulled by the core L can move in the pen axis direction without moving the operation lever 10.

The recess 2d serves to prohibit the movement of the operating lever 10 in the circumferential direction and to regulate the movement in the pen axis direction within a certain range. On the bottom surface of the recess 2d, two recesses 2da and 2db each having a shape to be fitted to the unit positioning R ball 10e are provided. The recesses 2da and 2db are juxtaposed along the pen axis direction in order from the rear end side of the mechanical pencil 1.

When the operating lever 10 is on the rearmost end side within the restricted movement range, the unit positioning R ball 10e is fitted in the recess 2da, and the movement of the operating lever 10 in the pen axis direction is gently restricted. (That is, it does not move unless a special force is applied). 1 and 2 show a case where the mechanical pencil 1 is in this state. As shown in these figures, in this state, the tip member 9 is housed in the tip bracket 3, and writing with the mechanical pencil 1 becomes impossible. Therefore, in the following, the position of the operating lever 10 at this time is referred to as a “pen tip storage position”.

When the operation lever 10 moves from the pen tip storage position toward the pen tip and the unit positioning R ball 10e is fitted in the recess 2db, the operation lever 10 is again gently restricted from moving in the pen axis direction. It will be in a state of being. As will be described in detail later, in this state, the tip member 9 protrudes from the tip bracket 3, and the chuck mechanism 6 continues to hold the core L while the writing pressure is applied. As a result, writing with the mechanical pencil 1 becomes possible. Therefore, in the following, the position of the operating lever 10 at this time is referred to as a "writing possible position" (first position).

When the operation lever 10 further moves from the writable position toward the pen tip and the unit positioning R ball 10e is about to come off from the recess 2db, the operation lever 10 moves to the frontmost side within the regulated movement range. To reach. Although details will be described later, in this state, the chuck mechanism 6 is in a state where the core L is released. Therefore, since a new core L can be sent to the tip member 9, the position of the operating lever 10 at this time is referred to as a "core replenishment position" (second position) below.

The core fixing grip 12 is a substantially cylindrical member, and is made of a non-ferrous metal such as brass or copper. The core fixing grip 12 is configured to have a convex portion 12a at the rear end and a truncated cone portion 12b at the front end. Of these, the truncated cone portion 12b has the shape of a truncated cone configured so that the pen axis is a truncated cone axis and the diameter increases toward the front end. As described above, the convex portion 12a located at the rear end of the core fixing grip 12 is fixed to the replacement core stocker 5 and the unit positioning lever 11. As a result, the core fixing grip 12 is configured to be movable in the pen axis direction in the second hollow portion 2b in conjunction with the replacement core stocker 5 and the unit positioning lever 11. The inside of the core fixing grip 12 penetrates from the front end to the rear end, and constitutes a hollow portion 12c which is a cylindrical space having a pen shaft as a cylindrical shaft.

The coil spring 13 is a spring arranged between the unit positioning lever 11 and the cam bracket 14, and is composed of, for example, a round wire coil. The coil spring 13 serves to urge the cam bracket 14 toward the pen tip. The elastic force of the coil spring 13 is set to a value smaller than the elastic force of the coil spring 7, which will be described later. This is a setting for advancing the core fixing grip 12 when the writing pressure applied to the pen tip during writing becomes 0, the coil spring 7 expands, and the tip member 9 advances. Details will be described later with reference to FIG.

The cam bracket 14 is a substantially cylindrical member made of a non-ferrous metal such as brass or copper. The outer diameter of the cam bracket 14 is set to be slightly smaller than the inner diameter of the first hollow portion 3b, whereby the cam bracket 14 can move in the first hollow portion 3b in the pen axis direction without shaking. It is configured. The inside of the cam bracket 14 penetrates from the front end to the rear end, and constitutes a hollow portion 14a which is a cylindrical space having a pen shaft as a cylindrical shaft. About half of the inner peripheral surface of the hollow portion 14a on the pen tip side is a tapered surface 14aa configured so that the diameter increases toward the front end. The truncated cone portion 12b of the core fixing grip 12 is inserted into the hollow portion 14a. The rear end side surface of the cam bracket 14 may or may not be fixed to the front end of the coil spring 13 by, for example, an adhesive.

The stopper 15 is a cylindrical member composed of, for example, a resin molded part, and serves to regulate the movement of the chuck mechanism 6 toward the pen tip side from the front end of the first hollow portion 3b. The outer diameter of the stopper 15 is set to a value at which a fitting relationship is established with the foremost end portion of the first hollow portion 3b. As a result, when the stopper 15 is located at the foremost end portion of the first hollow portion 3b, the stopper 15 is in a state of being gripped by the first hollow portion 3b with a constant gripping force. On the other hand, when the stopper 15 is located in the other portion of the first hollow portion 3b, the stopper 15 can move in the first hollow portion 3b in the pen axis direction without shaking in a state where the gripping force does not work. It is composed of.

The inside of the stopper 15 also penetrates from the front end to the rear end, and constitutes a hollow portion 15a which is a cylindrical space having a pen shaft as a cylindrical shaft. The diameter of the hollow portion 15a is set to a value that allows one core L to pass through without resistance, while a plurality of cores L cannot pass through.

The stopper 15 is fixed to the front end side surface of the cam bracket 14 with a force stronger than the gripping force of the first hollow portion 3b due to the fitting, for example, by an adhesive. This fixing is a configuration necessary for allowing the tip member 9 to be housed in the tip bracket 3 when the operation lever 10 is in the pen tip storage position. More specifically, when the operation lever 10 is moved from the writable position to the pen tip storage position, the core fixing grip 12 retracts, and the cam bracket 14 retracts accordingly. At this time, if the stopper 15 and the cam bracket 14 are not adhered to each other, the stopper 15 remains located at the foremost end of the first hollow portion 3b even if the cam bracket 14 is retracted. 9 cannot be stored in the tip bracket 3. On the other hand, if the stopper 15 and the cam bracket 14 are adhered with a force stronger than the gripping force of the first hollow portion 3b due to the fitting, the stopper 15 also retracts as the cam bracket 14 retracts. Therefore, the tip member 9 can be housed in the tip bracket 3. If the stopper 15, the coil spring 7, the bracket 8, and the tip member 9 are bonded at their respective boundaries, the tip member 9 is automatically housed in the tip bracket 3 as the stopper 15 retracts. Will be. On the other hand, if the stopper 15, the coil spring 7, the bracket 8, and the tip member 9 are not bonded at any boundary, the tip bracket of the tip member 9 can be pressed by pressing the pen tip against the writing surface S or pushing it with a finger. Storage in 3 is realized.

FIG. 4 is a diagram illustrating the operation of the core fixing grip 12. 4 (a) and 4 (b) are a bottom view and a cross-sectional view when the core fixing grip 12 is relatively on the upper side with respect to the position of the cam bracket 14, respectively. 4 (c) and 4 (d) are a bottom view and a cross-sectional view when the core fixing grip 12 is relatively lower with respect to the position of the cam bracket 14, respectively. Hereinafter, a more detailed configuration and operation of the core fixing grip 12 will be described with reference to these figures. In the following description, the position of the core fixing grip 12 corresponding to FIGS. 4 (a) and 4 (b) is simply referred to as "upper position", and the position of the core fixing grip 12 corresponding to FIGS. 4 (c) and 4 (d) is used. Is simply referred to as the "lower position".

First, referring to FIGS. 4A and 4C, the core fixing grip 12 is divided into six portions 12da to 12df at equal intervals along the circumferential direction. These portions 12da to 12df are interconnected at the rear end of the core fixing grip 12, and are urged outward through this connection. Although an example of dividing into six parts will be described here, the number does not have to be six and may be two or more. Further, the apex angle θ1 of the truncated cone portion 12b shown in FIG. 4B is set to the same value as the angle θ2 formed by the tapered surface 14aa with the pen axis in the cross section including the pen axis.

The illustrated distance G is the distance between the upper surface of the stopper 15 and the lower surface of the core fixing grip 12. In FIG. 4 (b) where the core fixing grip 12 is in the upper position, G> 0, and in FIG. 4 (d) where the core fixing grip 12 is in the lower position, G = 0.

As shown in FIG. 4B, G> 0 is when the core fixing grip 12 is not urged toward the front end. Details will be described later, but in such a case, when the operation lever 10 is in the pen tip storage position (see, for example, FIGS. 1 and 2) and when the operation lever 10 is in the writable position (writing pressure). This includes the time when writing is being performed. For example, it may occur in FIGS. 6, 8, 9, and 11 described later). At this time, as shown in FIG. 4B, a radial force indicated by an arrow A is applied from the tapered surface 14aa to the truncated cone portion 12b, so that the core fixing grip 12 has a core fixing grip 12 as shown in FIG. 4A. The portions 12da to 12df are in close contact with each other, and the core L is sandwiched by the core fixing grip 12. In the following, the diameter of the hollow portion 12c at this time is referred to as R1, and the diameter of the portion of the core fixing grip 12 other than the convex portion 12a and the truncated cone portion 12b is referred to as R2.

On the other hand, G = 0 as shown in FIG. 4D is when the core fixing grip 12 is urged toward the front end. Details will be described later, but in such a case, when the user intentionally sets the operation lever 10 to the core replenishment position (see, for example, FIG. 7 described later), the core L is oriented toward the front end by the core transport grip 22. It can occur when pulled (see, for example, FIG. 10 below). At this time, the force in the direction indicated by the arrow A shown in FIG. 4B disappears (or decreases), and as shown in FIG. 4C, the portions 12da to 12df of the core fixing grip 12 are expanded. Become. As a result, the hollow portion 12c also expands, so that the core fixing grip 12 is in a state where the core L is released. Therefore, the core L will fall in the direction indicated by the arrow B in FIG. 4D due to gravity.

Here, assuming that the diameter of the expanded hollow portion 12c is R1 + δ, the diameter of the portion of the core fixing grip 12 other than the convex portion 12a and the truncated cone portion 12b is also R2 + δ. The diameter R3 of the narrowest portion of the hollow portion 14a is set to a value equal to or slightly larger than this diameter R2 + δ. By doing so, when G = 0, the portions 12da to 12df of the core fixing grip 12 can be expanded and the core L can be released.

Return to FIG. The coil spring 7 is a spring made of a wire having a rectangular cross section, and urges the core protector 20 forward. The coil spring 7 and the stopper 15 may or may not be bonded. The inner diameter of the coil spring 7 is set to a value substantially equal to the diameter of the core L within the range in which the core L can pass without resistance. This setting is to prevent the end of the core L from floating in the air even at the portion of the coil spring 7, and by doing so, when the core L is replenished, the tip of the next core L is used. This makes it possible to support the rear end of the front core L. Details on this point will be described later. Further, the outer diameter of the coil spring 7 is set to be slightly smaller than the inner diameter of the second hollow portion 3c, whereby the coil spring 7 moves in the second hollow portion 3c in the pen axis direction without shaking. It is configured to be possible.

The bracket 8 is a cylindrical member arranged between the coil spring 7 and the tip member 9, and is composed of, for example, a metal part or a resin molded product formed by drawing. The bracket 8 and each of the coil spring 7 and the tip member 9 may or may not be bonded. The outer diameter of the bracket 8 is also set to be slightly smaller than the inner diameter of the second hollow portion 3c, whereby the bracket 8 is configured to be movable in the second hollow portion 3c in the pen axis direction without shaking. ing. The inside of the bracket 8 penetrates from the front end to the rear end, and constitutes a hollow portion 8a which is a cylindrical space having a pen shaft as a cylindrical shaft. The inner diameter of the hollow portion 8a is set to a value substantially equal to the diameter of the core L within the range in which the core L can pass without resistance. Further, the rear end of the hollow portion 8a communicates with the space inside the coil spring 7. The bracket 8 serves to connect the tip member 9 to the coil spring 7 and transmit the writing pressure applied to the tip member 9 to the coil spring 7.

The tip member 9 is a member that constitutes the pen tip of the mechanical pencil 1, and is composed of a core protector 20, a bracket 21, and a core transport grip 22.

FIG. 5 is an enlarged view of the tip member 9. The core protector 20 is a metal (more preferably stainless steel) part formed into a substantially cylindrical shape by drawing, and as shown in the figure, a flange 20a is provided at the rear end and a narrowed portion 20b is formed at the front end. It is configured to have each. The detailed manufacturing method of the core protector 20 will be described in detail later with reference to FIG. The flange 20a is a portion having a wider diameter than the other portion of the core protector 20, and the narrowed portion 20b is a portion having a smaller diameter than the other portion of the core protector 20. Since the core protector 20 is manufactured by drawing, the narrowed portion 20b has a smooth surface unique to drawing. As a result, the mechanical pencil 1 reduces the user's feeling of fatigue during writing.

The inside of the core protector 20 penetrates from the front end to the rear end, and constitutes the first hollow portion 20c and the second hollow portion 20d in order from the rear end side. Both the first hollow portion 20c and the second hollow portion 20d are cylindrical spaces having a pen shaft as a cylindrical shaft. Although details will be described with reference to FIG. 17, the second hollow portion 20d is provided in the narrowed portion 20b by, for example, drilling with a press. The diameter R4 of the first hollow portion 20c is set to a value larger than the diameter R5 (= inner diameter of the narrowed portion 20b) of the second hollow portion 20d.

The outer diameter of the core protector 20 is, for example, about 0.74 mm when a core L having a diameter of 3 mm is used. The diameter of the third hollow portion 3d is such that the core protector 20 can be moved by applying a certain amount of force in the pen axis direction while gripping the core protector 20 by fitting as described above. It is composed. When the operating lever 10 is in the pen tip storage position described above, the gripping force of the third hollow portion 3d prevents the tip member 9 from popping out due to its own weight from inside the tip bracket 3.

Further, the diameter R5 of the second hollow portion 20d is set to a value substantially equal to the diameter of the core L within a range in which the core L can pass without resistance. For example, when a core L having a diameter of 0.3 mm is used, the second hollow portion 20d may be provided by drilling using a punch having a diameter of 0.3 mm. By doing so, the diameter of the second hollow portion 20d can be made substantially equal to the diameter of the core L, so that it is possible to prevent the core L from breaking in the vicinity of the second hollow portion 20d.

The bracket 21 is a cylindrical member inserted at a position relatively rearward of the first hollow portion 20c, and like the bracket 8, for example, by a metal part or a resin molded product formed by drawing. It is composed. The outer peripheral surface of the bracket 21 is fixed to the inner peripheral surface of the core protector 20 by, for example, an adhesive. The inside of the bracket 21 penetrates from the front end to the rear end, and constitutes a hollow portion 21a which is a cylindrical space having a pen shaft as a cylindrical shaft.

The core transfer grip 22 is a cylindrical member inserted at a position relatively forward of the first hollow portion 20c, and is an elastic material having a certain elastic force such as resin, silicon, leather, cork, and cloth. Consists of. The outer peripheral surface of the core transport grip 22 is also fixed to the inner peripheral surface of the core protector 20 by, for example, an adhesive. This fixing is for preventing the core transport grip 22 made of a relatively soft material from losing its shape, and may not be fixed if there is no risk of losing its shape. The inside of the core transfer grip 22 also penetrates from the front end to the rear end, and constitutes a hollow portion 22a which is a cylindrical space having a pen shaft as a cylindrical shaft.

The outer diameters of the bracket 21 and the core transfer grip 22 are set to a value larger than the diameter R5 of the second hollow portion 20d. This prevents the bracket 21 and the core transfer grip 22 from falling off through the second hollow portion 20d.

The diameter of the hollow portion 21a is set to the same value as the diameter R5 of the second hollow portion 20d. Therefore, the core L can pass through the hollow portion 21a without resistance. On the other hand, the diameter of the hollow portion 22a is set to a value slightly smaller than the diameter R5. Therefore, when looking only at the diameter of the hollow portion 22a, the core L cannot pass through the hollow portion 22a, but since the core transport grip 22 is made of a material having a certain elastic force, a force is applied in the pen axial direction. Is added, the core L can be passed through the hollow portion 22a. When the force in the pen axis direction disappears while the core L is located in the hollow portion 22a, the core L is gripped by the core transport grip 22 and cannot move.

The structure of the mechanical pencil 1 has been described above. Next, the operation of the mechanical pencil 1 will be described in detail with reference to FIGS. 6 to 10.

FIG. 6 is an enlarged view of the tip portion of the mechanical pencil 1 when the operation lever 10 is set at a writable position. As shown in the figure, in this case, the stopper 15 moves to the front end of the movable range (the boundary between the first hollow portion 3b and the second hollow portion 3c), and the core is fixed by the elastic force of the coil spring 13. The grip 12 is urged toward the rear end, and the distance G between the upper surface of the stopper 15 and the lower surface of the core fixing grip 12 becomes a value larger than 0. Further, as the stopper 15 moves to the front end, the tip member 9 is in a state of protruding from the tip bracket 3.

FIG. 6 shows a case where the core L is still in the replacement core stocker 5 when the operation lever 10 is set to the writable position. In this case, since the urging force toward the front end is not applied to the core fixing grip 12, the core fixing grip 12 is in a state of sandwiching the core L as described with reference to FIGS. 4A and 4B. .. Therefore, even if the core L in the replacement core stocker 5 starts moving to the pen tip according to gravity, it cannot pass through the core fixing grip 12, and as shown in FIG. 6, it is inside the core fixing grip 12. It will be in a state of stopping at about.

FIG. 7 is an enlarged view of the tip portion of the mechanical pencil 1 when the operation lever 10 is moved from the state of FIG. 6 to the core replenishment position. In this case, since the urging force toward the front end is applied to the core fixing grip 12 by the unit positioning lever 11, as described with reference to FIGS. 4 (c) and 4 (d), the upper surface of the stopper 15 and the core fixing grip 12 The distance G from the lower surface becomes 0, and the core fixing grip 12 is in a state of releasing the core L. As a result, the core L, which has stopped in the middle of the core fixing grip 12, moves to the pen tip according to gravity. However, since it is merely free-falling, the movement of the core L stops when the tip of the core L reaches the inside of the core transport grip 22.

FIG. 8 is an enlarged view of the tip portion of the mechanical pencil 1 when the operating lever 10 is returned to the writable position from the state of FIG. 7. In this case, the urging force applied to the core fixing grip 12 from the unit positioning lever 11 disappears, and the core L is again held by the core fixing grip 12.

FIG. 9 is an enlarged view of the tip portion of the mechanical pencil 1 when writing is started by bringing the pen tip into contact with the writing surface S in the state of FIG. In addition, in FIG. 10 and FIG. 10, the mechanical pencil 1 is drawn vertically and the writing surface S is drawn diagonally due to the space of the paper surface, but in many cases, the writing surface S is horizontal and the mechanical pencil is drawn. 1 is diagonal.

When writing pressure is applied to the pen tip, the coil spring 7 contracts and the tip member 9 retracts. The writing pressure is also transmitted to the stopper 15 via the coil spring 7, but since the movement of the stopper 15 is restricted by the gripping force of the foremost end portion of the first hollow portion 3b, the stopper 15 and the cam bracket 14 are used. There is no retreat. Therefore, since the core fixing grip 12 continues to hold the core L at a fixed position, the core L protrudes from the tip member 9 without retracting due to the writing pressure, and is in a state where writing is possible.

FIG. 10 is an enlarged view of the tip portion of the mechanical pencil 1 when the pen tip is separated from the writing surface S in the state of FIG. When the writing pressure applied to the pen tip becomes 0, the coil spring 7 expands and the tip member 9 advances. At this time, the core fixing grip 12 is urged toward the front end through the core L gripped by the core transport grip 22. The core fixing grip 12 is urged toward the rear end by the elastic force of the coil spring 13, but the elastic force of the coil spring 7 and the gripping force of the core L by the core transport grip 22 overcome this urging force, and the recess 10b The core fixing grip 12 is advanced within the range of play. As a result, the distance G between the upper surface of the stopper 15 and the lower surface of the core fixing grip 12 becomes 0, and the core fixing grip 12 releases the core L. Therefore, the core L also advances as the tip member 9 advances. .. Therefore, the core L is automatically extended without knocking.

FIG. 11 is an enlarged view of the tip portion of the mechanical pencil 1 when writing is continued and the lead L is shortened and only a small portion of the rear end is sandwiched between the lead fixing grips 12. Further, FIG. 12 is an enlarged view of the tip portion of the mechanical pencil 1 when the pen tip is separated from the writing surface S in the state of FIG. As shown in FIG. 12, in this case, the rear end of the core L separates from the core fixing grip 12 as the tip member 9 advances. Then, even if the writing is restarted after this, the core L that is not sandwiched by the core fixing grip 12 recedes due to the writing pressure, so that the writing cannot be performed well. Even in such a case, writing can be continued if there is the next core L. Hereinafter, a detailed description will be given with reference to FIGS. 13 and 14.

FIG. 13 is an enlarged view of the tip portion of the mechanical pencil 1 when the next lead L is present in the replacement lead stocker 5 when the pen tip is separated from the writing surface S in the state of FIG. 11. Further, FIG. 14 is an enlarged view of the tip portion of the mechanical pencil 1 when the pen tip is brought into contact with the writing surface S and writing is continued in the state of FIG. 13. In the following description, the first core L is referred to as a core L1, the next core L is referred to as a core L2, and these are distinguished.

In FIG. 13, the next core L2 falls beyond the front end of the core fixing grip 12 by sewing a gap in which the core fixing grip 12 is released due to the disappearance of the writing pressure, and comes into contact with the rear end of the core L1. The case is shown. The core fixing grip 12 returns to the rear end side due to the elastic force of the coil spring 13 when the rear end of the core L1 is separated from the core fixing grip 12, so that the core fixing grip 12 comes into contact with the rear end of the core L1 depending on the timing. There is a possibility that the fall of the core L2 will stop before. Such cases will be described later with reference to FIGS. 15 and 16.

When writing is started with the front end of the core L2 in contact with the rear end of the core L1, as shown in FIG. 14, the core fixing grip 12 is in a state of sandwiching the core L2. In addition, in the mechanical pencil 1, the coil spring 7 is formed of a wire having a rectangular cross section, and the inner diameter thereof is substantially equal to the diameter of the core L. Therefore, even in the portion of the coil spring 7, the ends of the cores L1 and L2 are used. Since the portion does not float in the air, the rear end of the core L1 can be supported by the tip of the core L2. Therefore, since the retreat of the core L1 due to the writing pressure is prevented, writing can be continued as usual.

FIG. 15 is an enlarged view of the tip of the mechanical pencil 1 when the next lead L is present in the replacement lead stocker 5 when the pen tip is separated from the writing surface S in the state of FIG. 11, as in FIG. Is. The figure shows a case where the next core L2 has fallen due to the disappearance of pen pressure, but the fall has stopped before it comes into contact with the rear end of the core L1. Further, FIG. 16 is an enlarged view of the tip portion of the mechanical pencil 1 when the operation lever 10 is set at the core replenishment position in the state of FIG.

In the state as shown in FIG. 15, since the tip of the core L2 can no longer support the rear end of the core L1, the core L1 recedes due to the writing pressure, and it becomes impossible to write well. At this time, as shown in FIG. 16, by setting the operation lever 10 once at the core replenishment position, it is possible to obtain a state in which the core L2 falls and the cores L1 and L2 are in contact with each other again. Therefore, the retreat of the core L1 due to the writing pressure is prevented, and writing can be continued as usual as in the case of FIG.

By the way, as in the example shown in FIG. 14, when the core L1 becomes short and the core L1 gripped by the core transport grip 22 and the core L2 sandwiched by the core fixing grip 12 are different from each other. Even if the core L1 advances due to the expansion of the coil spring 7 with the disappearance of the writing pressure, the core fixing grip 12 cannot be advanced. Therefore, automatic feeding will not work. However, if the operation lever 10 is once set at the core replenishment position as shown in FIG. 16 and the core L2 is dropped, it is possible to obtain a state in which the cores L1 and L2 are in contact with each other again. Therefore, the retreat of the core L1 due to the writing pressure is prevented, and writing can be continued as usual. Then, since this state can be maintained as long as the core L1 is held by the core transport grip 22, according to the mechanical pencil 1, the core L1 is used until the remaining length is equal to or less than the thickness of the core protector 20. It will be possible to continue using.

FIG. 17 is a flow chart showing a manufacturing process of the core protector 20. Hereinafter, the method for manufacturing the core protector 20 shown in FIG. 5 will be described in detail with reference to FIG. 17.

The core protector 20 is manufactured by using a progressive die and feeding blanks. Specifically, first, a cylindrical protruding portion is formed on a plate-shaped blank by drawing (step S1). Specifically, a blank is pressed using a punch and a die. In step S1, the press may be performed a plurality of times. The tip of the protruding portion formed in this way becomes the narrowed portion 20b described above, but since it is formed by drawing, the surface of the narrowed portion 20b becomes a smooth surface unique to drawing. Therefore, it is possible to reduce the user's feeling of fatigue during writing.

Next, by performing drilling using a punch and a die, a hole having a smaller diameter than the inner diameter of the protruding portion is formed on the bottom surface of the tip (narrowed portion 20b) of the protruding portion (step S2). This hole becomes the second hollow portion 20d shown in FIG.

Finally, the protruding portion is separated from the blank by trimming the blank leaving the flange 20a shown in FIG. 5 (step S3). The portion thus separated constitutes the core protector 20 shown in FIG. Finally, deburring is performed as necessary to complete the core protector 20.

As described above, according to the mechanical pencil 1 according to the present embodiment, the lead transfer grip 22 can be provided near the tip of the lead protector 20, so that the amount of wasted lead L can be reduced. Become. Further, as long as the core L is in the replacement core stocker 5, writing can be continued.

Further, according to the mechanical pencil 1 according to the present embodiment, the coil spring 7 is formed of a wire having a rectangular cross section, and the inner diameter thereof is substantially equal to the diameter of the core L. Therefore, even in the portion of the coil spring 7. Since the end of the core L can be prevented from floating in the air, the tip of the next core L2 can support the rear end of the previous core L1.

Further, according to the manufacturing method described with reference to FIG. 17, the core protector 20 is manufactured by drawing processing capable of forming an ultrafine (typically, an outer diameter of about 0.74 mm) bottomed cylinder, which is good. It is possible to form a narrowed portion 20b at the tip of the core protector 20 to prevent the core transport grip 22 from falling while ensuring a good writing quality. Further, since the surface of the narrowed portion 20b becomes a smooth surface unique to drawing processing, it is possible to reduce the user's feeling of fatigue during writing.

Further, since the core transport grip 22 is made of an elastic material such as silicon, according to the mechanical pencil 1 according to the present embodiment, the core L1 is not sandwiched by the core fixing grip 12, for example, as shown in FIG. Even if it becomes, the rotation of the core L1 is unlikely to occur, and as a result, the tip of the core L1 is unlikely to be shaped like a cut diagonally cut bamboo with a Japanese sword. It also has the effect of preventing the occurrence of situations that damage the paper surface, such as swords.

Further, according to the mechanical pencil 1 according to the present embodiment, since the structure is simple, it is possible to reduce the number of parts and the manufacturing cost. In addition, since the body is divided into three parts (housing 2, tip bracket 3, and head cap (not shown), there is a high degree of freedom in design, so despite the low price, it should have a high-class feel. Will also be possible.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and the present invention can be implemented in various embodiments without departing from the gist thereof. Of course.

For example, in FIG. 17, an example in which the production of the core protector 20 is completed in the progressive press process has been described, but the core protector 20 may be manufactured by executing the single-shot press process a plurality of times, or a step. Instead of executing S2, the second hollow portion 20d may be formed by drilling a hole using a lathe after step S3. Further, instead of the press, the core protector 20 may be manufactured by using electroplating or a 3D printer.

1 Mechanical pencil 2 Housing 2a First hollow part of housing 2 2b Second hollow part of housing 2c Third hollow part of housing 2 2d, 2da, 2db Recessed part of housing 2e Housing 2 Through hole 3 Tip bracket 3a Convex part of tip bracket 3 b First hollow part of tip bracket 3c Second hollow part of tip bracket 3 3d Third hollow part of tip bracket 3 4 Eraser fixing bracket 5 Replacement core Stocker 5a 1st hollow part of spare lead stocker 5b 2nd hollow part of spare lead stocker 5c 3rd hollow part of spare lead stocker 5 6 Chuck mechanism 7 Coil spring 8 Bracket 8a Hollow part 9 tip of bracket 8 Member 10 Operating lever 10a, 10b Recessed part of operating lever 10 10c Coil spring 10d Plate-shaped body 10e Unit positioning R ball 11 Positioning lever 11a Opening 11b Protrusion 12 Core fixing grip 12a Convex part 12b of core fixing grip 12 Cone base 12c Hollow part of the core fixing grip 12 12da to 12df Part of the core fixing grip 12 13 Coil spring 14 Cam bracket 14a Hollow part of the cam bracket 14 14a Hollow part 14a of the cam bracket 14 Tapered surface 15 Stopper 15a Stopper 15 Hollow part 20 Core protector 20a Flange 20 of core protector 20 narrowed part 20c, 20d of core protector 20 Hollow part of core protector 20 Bracket 21a Hollow part of bracket 21 22 Core transfer grip 22a Hollow part of core transfer grip 22 R Core clogging Release bar E Eraser L, L1, L2 Core S Writing surface

Claims (4)

A metal core protector formed by drawing to have a constriction at the front end and movable along the pen axis direction.
A cylindrical core transport grip that is inserted at a position relatively forward of the inside of the core protector and has an outer diameter larger than the inner diameter of the constricted portion.
A cylindrical bracket inserted at a position relatively rearward of the inside of the core protector and fixed to the core protector,
A coil spring that urges the core protector forward, and
A chuck mechanism that is configured to be movable along the pen axis direction and has a core fixing grip that holds the rear part of the core inserted in the core protector when retracting while releasing the core when moving forward.
Automatic pay-out type mechanical pencil equipped with. The coil spring is composed of a wire having a rectangular cross section.
The mechanical pencil according to claim 1. The chuck mechanism has an operation lever arranged on the side surface of the housing of the mechanical pencil and fixed to the core fixing grip.
In the chuck mechanism, when the operating lever is in the first position, the core fixing grip holds the rear portion of the core, and when the operating lever is in the second position, the core fixing grip is the core. Is configured to release,
The mechanical pencil according to claim 1 or 2. A step of forming a cylindrical protrusion on a metal blank by drawing,
A step of forming a hole having a diameter smaller than the inner diameter of the protruding portion on the bottom surface of the protruding portion by drilling.
A step of acquiring a core protector constituting the pen tip of an automatic pay-out mechanical pencil by separating the protruding portion from the blank by trimming the blank while leaving a flange.
How to manufacture a lead protector for automatic mechanical pencils including.

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