JP6409388B2 - mechanical pencil - Google Patents

Description

  The present invention relates to a mechanical pencil in which a lead supply pipe is disposed in an inner hole of a chuck body, and the lead is guided from a lead tank to the chuck body through the lead supply pipe.

  One example is Japanese Utility Model Publication No. 63-132780 (Patent Document 1). The claim of the utility model is “a chuck that is urged axially rearward by a chuck spring in the shaft cylinder and abutted against the fastener, and separated from the chuck and urged axially rearward by a return spring. And a pipe secured to the core tank directly or via a connector, and the pipe is inserted into the rear cylinder of the chuck at a slight distance from the chuck. "Opening device".

  In Patent Document 1, when the lead is extended, the lead tank is advanced against the elastic force of the return spring, and the tip of the pipe is brought into contact with the tapered inner stage behind the lead holding part of the chuck. Then, the chuck moves forward against the elastic force of the chuck spring and feeds the lead by a certain amount. When the pipe is further advanced, the chuck head is detached from the fastener, and the chuck is pushed and expanded by the pipe, that is, the chuck can be expanded as the pipe advances. In the following, the base 3 side is referred to as the front, and the lead tank 11 side is referred to as the rear.

Japanese Utility Model Publication No. 63-132780

In the prior art described in the above-mentioned Patent Document 1, in a state where the writing core is short and there is a contact surface between the rear end of the writing core and the front end of the subsequent core near the front end surface of the pipe 8 in the chuck. When the chuck 6 is moved forward to perform the pressing operation of feeding out the lead, the writing lead advances and the subsequent lead advances in series. In this state, if the protruding lead core is retracted, the contact core between the trailing edge of the writing lead and the leading edge of the trailing lead will be misaligned and the two leads will be in a parallel state. Since the end of the pipe 8 is pressed into the hole of the pipe 8 and the pipe 8 is clogged together with the subsequent core, the subsequent core may not be fed out. In particular, when the writing core is shortened and separated from the core biting portion of the chuck body, and the so-called remaining core state is reached, the fixing of the writing core is only the core holding member, and the rear end of the writing core is fixed. Since the misalignment increases, the misalignment of the axial center of the contact surface between the trailing end of the lead and the leading end of the succeeding lead is more likely to occur.
This phenomenon is caused by the fact that the front end surface of the pipe 8 has moved to the vicinity of the locking step 3A of the base 3 in the state shown in FIG. 6, there is a rear end of the remaining core in the vicinity of the position of the front end surface, and the distance from which the rear end of the remaining core comes into contact with the pipe 8 at the time of the maximum pressing operation due to the point reaching the inside from the locking step 3A of the base 3 It is thought to be caused by the cause. The pressing length of the pressing operation for feeding out the lead is the length until the front end of the connector 9 comes into contact with the rear outer step 6a of the chuck 6, and the front end surface of the chuck 6 in FIG. The touched length is added. During the pressing operation, when the front end of the connector 9 contacts the rear outer stage 6 a of the chuck 6, the front end of the pipe 8 contacts the rear portion of the core holding portion 6 c of the chuck 6.

The present invention provides a mechanical pencil that moves a chuck body back and forth by pressing from the rear and opens and closes a core from a tip hole of a tip member, and has an inner diameter portion that regulates the amount of expansion when the chuck body is advanced and opened. A sliding member in which a pipe projecting from the tip member is fixed to the front and a core holding member is fixed inside and a core is inserted through the center of the pipe is provided by the front end surface of the chuck body. The tip member is provided so as to slide back and forth with respect to the shaft core, the core supply pipe is included in the chuck body, and the distance from the front end surface of the core supply pipe to the front end surface of the core body is pressed from the rear. longer than the maximum movement distance of the chuck body front face which moved back and forth by hand, the distance from the rear end of the sliding member to said chuck body front end, a pipe of said sliding member from said destination member Also summarized in that was longer than the protrusion distance of the protruded state.

The present invention provides a mechanical pencil that moves a chuck body back and forth by pressing from the rear and opens and closes a core from a tip hole of a tip member, and has an inner diameter portion that regulates the amount of expansion when the chuck body is advanced and opened. A sliding member in which a pipe projecting from the tip member is fixed to the front and a core holding member is fixed inside and a core is inserted through the center of the pipe is provided by the front end surface of the chuck body. The tip member is provided so as to slide back and forth with respect to the shaft core, the core supply pipe is included in the chuck body, and the distance from the front end surface of the core supply pipe to the front end surface of the core body is pressed from the rear. longer than the maximum movement distance of the chuck body front face which moved back and forth by hand, the distance from the rear end of the sliding member to said chuck body front end, a pipe of said sliding member from said destination member Because also longer than the projection distance of the protruded state, a possible pipe protruding from the fixed destination member to the front end of the sliding member, falling or carrying the mechanical pencil as can be accommodated when not in use or portable in previously member In addition to protecting the pipe, it is possible to prevent the pipe from being caught when put in the pocket of clothes, and writing with the front end surface of the writing core being approximately the same position as the front end surface of the pipe is also possible In addition, when the pipe projecting from the tip member is stored after use, the contact surface between the projecting core rear end and the subsequent core front end in the writing which has become the remaining core state touches the core supply pipe front end surface. In the lead supply pipe, the writing lead and the following lead are not in a parallel state, so that the lead is not clogged in the lead supply pipe and a good centering operation is obtained.

It is an external appearance front view of a present Example. It is a right side external view of FIG. It is a longitudinal cross-sectional view in FIG. It is a front enlarged view in FIG. It is a front enlarged view in FIG. FIG. 5 is an enlarged view around a middle screw member 11 in FIG. 4. FIG. 7 is an enlarged ZZ cross-sectional view in FIG. 6. FIG. 5 is a rear enlarged view in FIG. 4. FIG. 4 is an enlarged front perspective view of the core feeding unit 6 of FIG. 3. It is an external appearance front view of the axial cylinder main body 5 of a present Example.

The operation will be described. The present invention provides a mechanical pencil that moves a chuck body back and forth by pressing from the rear and opens and closes a core from a tip hole of a tip member, and has an inner diameter portion that regulates the amount of expansion when the chuck body is advanced and opened. Provided in the member, the chuck body includes a core supply pipe, and the distance from the chuck body front end surface to the front end surface of the core supply pipe is larger than the maximum movement distance of the chuck body front end surface that moves back and forth by pressing from the rear. Since the length is increased, the core supply pipe does not come into contact with the rear end of the core during writing at the time of maximum centering knock, so that the core supply pipe does not clog.
The present invention is an example of a rear end knock type mechanical pencil.

  A first embodiment of the present invention will be described with reference to FIGS. In addition, below, the front member 4 side mentioned later is called the front, and the press member 18 side is called back.

The shaft tube 1 includes a tip member (one shaft tube) 4 and a shaft tube main body (the other shaft tube) 5 disposed at the rear end of the tip member 4. A core feeding unit (middle shaft) 6 is arranged in the.
A sliding member 25 is disposed inside the front of the tip member 4. A stainless steel pipe 2 is press-fitted and fixed to the sliding member 25, and a core holding member 3 is press-fitted and fixed inside. Has been. The core holding member is slid so that the position where the core is held is close to the chuck front end surface and the front end of the core supply pipe in order to reduce the misalignment of the shaft core between the contact surface of the rear end of the core and the front end of the subsequent core. It is arranged behind the moving member. Further, a step portion 4 b is formed in the middle of the tip member 4. Further, the tip inner diameter portion 4d of the tip member 4 has an inner diameter into which the outer diameter of the pipe 2 can be inserted. Here, the distance from the rear end of the sliding member 25 to the front end of the chuck body 9 (described later) of the core feeding unit (middle shaft) 6 is longer than the distance in which the pipe 2 protrudes most from the tip member 4. Thereby, the pipe 2 press-fitted and fixed in front of the sliding member 25 can be accommodated in the tip member 4 when not used or carried.
A plurality of concave grooves 5a are arranged on the front outer peripheral portion of the shaft cylinder main body 5 to provide an anti-slip effect. Further, the shaft body 5 is sandwiched between the tip member 4 and the core feeding unit 6, and by screwing the tip member 4 and the core feeding unit 6 as described later, The shaft cylinder main body 5 is fixed (clamped).
Reference numeral 23 denotes a metal clip attached to the upper part of the shaft cylinder main body 5. The clip 23 is fitted in a recess 24 formed at the rear of the shaft cylinder body 5. The front end of the mounting portion 23a of the clip 23 to the shaft cylinder main body 5 is formed in an arc shape, and the front end of the recessed portion 24 to be fitted is also formed in an arc shape. Thereby, the tip (small) side of the mounting portion 23a of the clip 23 can be inserted from the large portion of the recess 24 at the start of mounting, and is guided by the arc-shaped portion, so that the clip 23 can be easily mounted on the shaft cylinder body 5. Yes.

The core feeding unit (core feeding mechanism) 6 will be described in detail.
The lead feeding unit (lead feeding mechanism) 6 has a lead tank 7 for storing the lead, and a relay member 8 is fixed to the front end of the lead tank 7 by press fitting. A chuck body 9 for holding and releasing the core L is fixed in front of the intermediate member 8, and a chuck ring 10 for opening and closing the chuck body 9 is surrounded by the chuck body 9. Is arranged in. The chuck body 9 grips and releases the core L by a large diameter portion formed in front of the chuck body 9. The chuck body 9 is composed of a plurality of chuck pieces divided. In this embodiment, the chuck pieces 9c, 9d, and 9e are divided into three parts, and are connected by a base 9f. Slits 9g, 9h, 9i are formed between the chuck pieces 9c, 9d, 9e. Further, an intermediate screw member 11 is disposed so as to enclose the intermediate member 8, the chuck body 9, and the chuck ring 10. Further, a core supply pipe 50 for supplying only one core reliably to the core biting portion 9a of the chuck body 9 is disposed inside the intermediate member 8 and the chuck body 9. In this embodiment, the core supply pipe 50 is loosely inserted into the through hole 8a of the relay member 8 and the through hole 9b of the chuck body 9, but either the intermediate member 8 or the chuck body 9 or It may be fixed to both. The lead supply pipe 50 has an inner diameter that is slightly larger than the outer diameter of the lead L to be used, so that only one lead L stored in the lead tank 7 can pass therethrough. The rear end of the lead supply pipe 50 is formed in a funnel shape 50a in order to guide the subsequent lead into the lead supply pipe 50. Further, since the maximum outer diameter of the funnel-shaped 50 a is larger than the through hole 8 a of the intermediate member 8, the core supply pipe 50 does not move in the direction of the core biting portion 9 a of the chuck body 9 even when the tip member 4 side is down. Do not move. The positioning of the intermediate screw member 11 is performed by contacting the stepped portion 12 formed inside the front portion of the intermediate screw member 11 with the rear end surface of the chuck ring 10 and the large diameter formed at the rear portion of the intermediate screw member 11. It is formed by a resilient member (coil spring) 15 stretched between the rear end of the portion 13 and the front end of the step portion 14 formed by two kinds of reduced diameter portions in front of the core tank 7. The elastic member 15 biases the chuck body 9, the relay member 8 and the core tank 7 to the rear of the shaft cylinder 1 when the core feeding unit 6 is disposed in the shaft cylinder 1. The outer periphery of the large diameter portion 13 of the middle screw member 11 has a polygonal cross section. In the present embodiment, a regular hexagon is formed (FIG. 7). Further, at the rear end of the lead tank 7, there are an eraser receiving member 16, an eraser 17 held by press fitting to the eraser receiving member 16, a lead removing pin 51 fixed to the eraser 17 by press fitting, and a pressing member 18. It is detachably attached.

Here, a method of fixing the shaft cylinder main body 5 by the tip member 4 and the core feeding unit 6 will be described in detail. A female screw portion 19 is formed on the rear inner surface of the tip member 4, while a male screw portion 20 is formed on the outer surface of the reduced diameter portion 11 a of the middle screw member 11 in the core feeding unit 6. ing.
The shaft cylinder main body 5 has a small-diameter portion 21 on its front inner surface, and a step portion 22 is formed at the rear end of the small-diameter portion 21. The inner diameter cross section of the portion where the large diameter portion 13 is disposed from the rear of the step portion 22 has a polygonal shape. In this embodiment, the polygonal outer peripheral shape is formed to be the same as the outline (star-shaped regular dodecagon outline) when the centers of two regular hexagons are aligned and shifted by 30 degrees (star-shaped regular dodecagon outline) ( FIG. 7). By positioning the stepped portion 22 of the shaft cylinder body 5 and the front end of the large-diameter portion 13 of the middle screw member 11 to position the core feeding unit 6 within the shaft tube body 5, By screwing the male screw portion 20 of the intermediate screw member 11 and the female screw portion 19 of the tip member 4 projecting from the shaft tube main body 5 until the tip member 4 and the shaft tube main body 5 come into contact with each other, the shaft The cylinder body 5 is clamped. Here, due to the polygonal shape (regular hexagonal shape) of the large-diameter portion 13 and the polygonal shape of the inner diameter of the shaft cylinder main body 5, relative rotation between the core feeding unit 6 and the shaft cylinder main body 5 at the time of screwing is performed. Can be prevented. The polygonal shape of the large-diameter portion 13 and the polygonal shape of the shaft tube main body 5 are not limited to the above-described shapes, and may be any shape that can prevent relative rotation between the core feeding unit 6 and the shaft tube body 5. good.

The feeding of the lead L will be described.
When feeding the lead L, the rear end of the pressing member 18 is pressed. By this pressing operation, the lead tank 7, the intermediate member 8, and the lead supply pipe 50 move forward, the elastic member 15 is compressed, and the chuck body 9 also moves forward. At this time, the lead L is also moved forward, the front end surface of the chuck ring 10 comes into contact with the stepped portion 4b of the tip member 4, and the chuck body 9 is expanded. And even after the chuck body 9 is expanded, the forward movement of the chuck body 9 is performed. When the pressing operation of the pressing member 18 is released, the core tank 7, the joining member 8, the chuck body 9, and the core supply pipe 50 are retracted by the action of the compressed elastic member 15 to return to the original state, and the chuck body. 9 is closed by the chuck ring 10 and grips the core L again. However, the lead L is fixed by the lead holding member 3 at a position advanced by the pressing operation. This completes the lead L feeding operation. In this embodiment, a rear end knock structure that presses the rear end of the pressing member is employed. However, it is sufficient that the chuck body can be moved back and forth and opened and closed by pressing from the rear. A structure such as a side knock, a side slide, or a folded knock can be employed, and is not particularly limited.
Note that the expansion of the chuck body 9 is regulated by the expansion regulating inner diameter 4 c of the tip member 4. In the chuck body 9 alone, the chuck pieces divided into a plurality of chuck bodies 9 are in a state of being expanded to an outer diameter that is larger than the expansion restriction inner diameter 4 c of the tip member 4. By restricting the expansion outer diameter of the chuck body 9 with the expansion restriction inner diameter 4c, the width of the three slits 9g, 9h, 9i is made smaller than the core diameter to be used. Therefore, since the chuck body 9 alone has a larger chuck body expansion outer diameter than the expansion restriction inner diameter 4c, a reliable centering operation and a light knock operation sound can be obtained, and the chuck body 9 can be expanded. Since it is regulated, the core L does not enter the slits 9g, 9h, 9i of the chuck body 9.
Furthermore, by restricting the expansion of the chuck body 9, the inner diameter of the core biting portion 9a of the chuck body 9 at the time of expansion is also reduced. Therefore, the expansion restriction of the chuck body 9 reduces the allowable range in which the core L in the core biting portion 9a of the chuck body 9 moves in the radial direction. The axis core of the contact surface between the rear end of the writing core and the front end of the succeeding core that is in series is not aligned, and the two cores are not in parallel, and the rear end of the writing core is connected to the pipe together with the subsequent core. There is no clogging. In addition, since the chuck body 9 supplies the lead L forward without shifting the center of the axis, and when the remaining core is in a state of remaining core, the subsequent core reliably pushes the remaining core. The effect of the dispensing operation can be achieved.
In this configuration, the core diameter of the core L is small, and the slit width of the chuck body 9 is likely to be wider than the usable core diameter. When there is a high possibility that both cores are in parallel, it is particularly effective for cores having a nominal diameter of 0.3 mm, 0.2 mm or less.
Here, the sliding of the sliding member 25 is interlocked with the pressing operation of the pressing member 18 when the core L is drawn out, and the core 2 is moved from the state in which the pipe 2 is accommodated in the tip member 4. By performing the feeding operation of L, the sliding member 25 moves forward. More specifically, when the rear end of the pressing member 18 is pressed while the pipe 2 is housed in the front member 4, the sliding member 25 is moved by the front end surface of the chuck body 9 advanced by the pressing operation. The rear end face is pressed and moves forward and slides. The forward movement of the sliding member 25 is performed until the front end of the large-diameter portion 25a formed on the outer periphery of the sliding member 25 abuts on the step portion 4a formed inside the tip member 4. When the front end of the large-diameter portion 25a of the sliding member 25 comes into contact with the stepped portion 4a in the tip member 4, the sliding member 25 reaches the most advanced position, and the pipe 2 protrudes from the tip member 4 to the maximum. It will be in the state. This length is defined as a pressing length A of the lead L feeding pressing operation (FIG. 4). Writing is possible when the pressing operation of the pressing member 18 for feeding out the core L is repeated and the core L is advanced to the front end face of the pipe 2.
When the pressing member 18 is pressed to advance / expand the chuck body 9 to release the core L, and the front end of the core L is pushed back, the pipe 2 is also fully accommodated in the tip member 4. As a result, the pipe 2 can be protected when the mechanical pencil is dropped or carried, and the pipe 2 can be prevented from being caught when put in a pocket of clothes.

In the mechanical pencil described in the present embodiment, the pipe 2 can be retracted during writing, and writing in a state where the front end surface of the core L is substantially at the same position as the front end surface of the pipe is also possible. It has become.
A minute gap is provided between the expansion restriction inner diameter 4 c of the tip member 4 and the outer peripheral surface of the large diameter portion 25 a of the sliding member 25. As for the size of the gap, when the lead L is not gripped by the lead holding member 3 in the sliding member 25, for example, when the lead L is not in the mechanical pencil, the tip member 4 is lowered. When it is directed, the sliding member 25 moves by its own weight and the pipe 2 protrudes from the tip member 4, and when the tip member 4 is directed upward, the pipe 2 is moved by its own weight and stored in the tip member 4 It is desirable that This is because writing can be performed without protruding the core L from the front end surface of the pipe 2, that is, even when the front end surface of the core L is located on the front end surface of the pipe 2. The gap between the expansion restriction inner diameter 4c of the tip member 4 and the outer peripheral surface of the large-diameter portion 25a of the sliding member 25 is preferably a minute gap without radial play. This is to prevent breakage of the core due to axial misalignment.
The core L is fed out, and the front end surface of the core L is substantially in the same position as the front end surface of the pipe 2, or the core L that originally protrudes from the front end surface of the pipe 2 is worn out by writing, Writing is performed in a state where the front end face is substantially in the same position as the front end face of the pipe 2. Then, the core L is worn by writing, and the pipe 2 is gradually retracted in conjunction with shortening. This is repeated until the pipe 2 is accommodated in the tip member 4, that is, while the pipe 2 protrudes from the tip member 4, writing is possible.
This configuration is particularly effective when the core L has a small core diameter and a low breakage load, specifically for cores having a nominal diameter of 0.2 mm or 0.3 mm. Writing is possible with the lead L guided from the pipe 2 without projecting the lead L from the pipe 2, so that the writing pressure increases or the writing pressure increases due to the change in writing pressure during writing. Even if the user uses it, breakage of the core L due to writing pressure can be prevented.

Here, the relationship between the lead supply pipe 50 and the aforementioned pressing length A will be described in detail.
The length of the core supply pipe 50 is determined by the following relationship. The length from the rear end surface of the sliding member 25 to the front end surface of the chuck body 9 is defined as a pressing length A of the core L in the extending pressing operation. Further, the length from the front end surface of the chuck body 9 to the front end surface of the core supply pipe 50 is defined as a distance B (FIG. 4). Regarding the relationship between the pressing length A and the distance B, the length of the core supply pipe 50 is set so that the distance B is longer (A <B).
On the other hand, in the configuration disclosed in Japanese Utility Model Publication No. 63-132780, which is taken up as the background art, the pipe 8 is inserted into the chuck 6, but as described in the above-mentioned problem, from the pressing length A, from the tip of the chuck. Since the distance B to the tip of the pipe 8 is shorter (A> B), when the core being written becomes shorter and away from the core biting portion of the chuck body, so-called remaining core state, Since only the core holding member is fixed and the blurring of the rear end surface of the core during writing becomes large, the axial center misalignment between the rear end surface of the core in writing and the front end surface of the succeeding core occurs. It is easy, and when performing the storing operation of the protruding lead, the writing lead and the following lead may be in a parallel state and clogged in the pipe 8 at the same time, and the lead may not come out.
However, in the present embodiment, the relationship between the pressing length A and the distance B sets the length of the core supply pipe 50 so that the distance B is longer (A <B). When performing the storing operation of the protruding writing core in the remaining core state, the contact surface between the trailing edge of the writing core and the leading edge of the succeeding core does not touch the leading edge of the core supply pipe 50, and the core supply pipe 50 Since the core is not clogged in the inside, a good centering operation can be obtained. The range in which the distance B can be set for the pressing length A and the length from the front end surface of the chuck body 9 to the front end surface of the core supply pipe 50 is appropriately selected while maintaining the relationship of A <B in the following range. To do.
A: (0.3 mm to 10.0 mm) <B: (0.4 mm to 60.0 mm)
Further, in the present embodiment, the configuration in which the sliding member 25 that slides in the tip member 4 is illustrated, but a structure in which the sliding member 25 is fixed to the tip member 4 may be used. The configuration in which the sliding member 25 that slides inside the tip member 4 has a longer residual core and moves the pipe 2 that is press-fitted and fixed in front of the sliding member 25 into the tip member 4. Since a distance is required, the distance to which the trailing end of the lead during writing in the remaining core state is inevitably increased. For this reason, there is a high possibility that the shaft cores of the contact surface of the core rear end and the subsequent core front end in writing that are in series will be misaligned, and both cores will be in a parallel state, and clogging in the pipe is likely to occur. Since the core clogging can be prevented by maintaining the relationship of A <B, the effect of preventing the core clogging by maintaining the relationship of A <B is the sliding member 25 that slides in the tip member 4 exemplified in the present embodiment. It can be said that the structure provided with is more prominent.

1 shaft cylinder 2 pipe 3 core holding member 4 tip member (one shaft cylinder)
4a Step portion 4b Step portion 4c Expanding restriction inner diameter 4d Tip inner diameter portion 5 Shaft cylinder body (the other shaft cylinder)
5a Concave groove 6 Core feed unit (middle shaft)
7 core tank 8 relay member 8a through hole 9 chuck body 9a core engaging portion 9b through hole 9c chuck piece 9d chuck piece 9e chuck piece 9f base 9g slit 9h slit 9i slit 10 chuck ring 11 medium screw member 11a reduced diameter portion
12 Step portion 13 Large diameter portion 14 Step portion 15 Elastic member (coil spring)
DESCRIPTION OF SYMBOLS 16 Eraser receiving member 17 Eraser 18 Pressing member 19 Female screw part 20 Male screw part 21 Small diameter part 22 Step part 23 Clip 23a Mounting part 24 Recessed part 25 Sliding member 25a Large diameter part 50 Core supply pipe 50a Funnel-shaped 51 Core removal pin A Knock stroke B Length from the tip of chuck body 9 to tip of lead supply pipe 50 L lead

Claims (2)

In a mechanical pencil that moves the chuck body back and forth by pressing from behind and opens and closes the core from the tip hole of the tip member, an inner diameter portion is provided in the tip member that regulates the amount of expansion when the chuck body is advanced and opened. In addition, a pipe projecting from the tip member is fixed to the front, and a core holding member is fixed to the inside. A sliding member through which the core is inserted is pressed by the front end surface of the chuck body, and the tip end surface is pressed. Provided in the member so as to slide back and forth with respect to the shaft core , the chuck body includes a core supply pipe, and the distance from the front end surface of the chuck body to the front end surface of the core supply pipe is moved back and forth by pressing from behind. longer than the maximum movement distance of the chuck body front face, the distance from the rear end of the sliding member to said chuck body front end, a pipe of said sliding member is most projected from the destination member Mechanical pencil, which was longer than the projection distance of the state.   2. The mechanical pencil according to claim 1, wherein an inner diameter portion is provided in the tip member for regulating an amount of expansion so that a width of the slit when the chuck body is advanced and opened is less than a core diameter to be used.

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