JP2010142956A - Mechanical pencil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mechanical pencil of simple constitution, capable of rotating a lead without rotating the whole of the internal structure such as a lead tank, although required in a prior art, in the mechanical pencil capable of rotating a tip of the lead. <P>SOLUTION: A lead holding part 41 is formed in an inside of a slider 42 provided to be movable longitudinally in a tip of a shaft tube 1, and cam parts 52, 53 are formed in a front face 46 and a rear face 47 of a head part 44. A front part stopper 48 and a rear part stopper 49 abutting on the head part 44 are provided in the shaft tube 1, the cam parts 52, 53 are formed to be meshed respectively with a cam part of the head part 44, and a pitch of the cam part 52 is shifted from that of cam part 53. A chuck 37 is constituted of a plurality of chuck elements 35, is inserted into a holding cylinder 26 via a ball 38, holds the lead, and is rotatable in the holding cylinder under a lead holding state. The slider 42 retreats when applying writing pressure, and advances when stopping writing. The slider 42 is rotated when retreating and advancing, to rotate the lead. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a mechanical pencil in which, when writing, the lead is rotated by separating the tip of the lead from the paper surface.

A normal mechanical pencil is held in a state where the lead is held with a strong force by the chuck of the lead feeding mechanism, so that it is almost impossible to rotate, and the lead may be reduced by one side when writing, resulting in a thick writing line. there were. In order to eliminate such a phenomenon, a mechanical pencil has been proposed in which the lead rotates when the tip of the lead is separated from the paper surface or pressed against the paper surface (see, for example, Patent Documents 1 and 2). However, what has been proposed in the past employs a collet chuck type mechanism as a chuck, and the collet chuck type chuck is fixed to the tip of the lead tank. In order to rotate the lead, the entire chuck mechanism, that is, It was necessary to rotate the entire internal mechanism such as the lead tank and knock spring to which the chuck mechanism is fixed. For this reason, none of the previously proposed mechanisms can easily transfer the structure of a conventional mechanical pencil, the internal mechanism is more complicated than that of a normal mechanical pencil, and the assembly is troublesome. It was difficult to get.
Japanese Patent No. 3882272 (Claims, paragraph 0011, FIG. 1, FIG. 3) International Publication No. 2007/142135 (paragraphs 0008, 0030, 0032, 0036, 0046, claims 1, FIG. 1, FIG. 5, FIG. 8)

  The problem to be solved by the present invention is a mechanical pencil in which the lead is rotated by separating the tip of the lead from the paper surface, and can be easily configured without changing the configuration of the conventional mechanical pencil, and is easy to assemble. It is to provide a mechanical pencil that can be obtained economically.

  The conventional lead rotation type mechanical pencil is configured so that the chuck mechanism holding the lead is rotated first, and the lead rotates due to the rotation of the chuck mechanism. There is a disadvantage as described above that the core tank must be configured so that it can be rotated together. Therefore, in the present invention, a slider for holding the lead is rotatably provided, and the lead is rotated by rotating the slider. In addition, a mechanism that allows only the chuck to freely rotate in the circumferential direction while holding the lead when the lead rotates is employed, so that the lead tank and the like need not be rotated. As such a rotatable chuck mechanism, there is a ball chuck type chuck conventionally used for an automatic feeding type mechanical pencil. In this ball chuck type chuck, the chuck is composed of a plurality of independent chuck elements, and a ball is inserted around the outer periphery of the chuck and inserted into a holding cylinder. A core tank or the like is fixed to the chuck element. Absent. Accordingly, since the ball interposed on the outer periphery can roll in the circumferential direction even when the core is strongly held by the chuck element, only the chuck can be rotated, and the core tank or the like need not be rotated. .

  The present invention has been invented on the basis of the above examination results. According to the present invention, a cylindrical holding cylinder having a tip enlarged portion whose inner diameter is gradually enlarged toward the front is provided in the shaft cylinder. The chuck is formed by combining a plurality of independent chuck elements having a core insertion groove in a cylindrical shape so as to surround the core and energizing in the forward and backward directions and energizing in the forward direction. A chuck is inserted between the outer surfaces of the chuck so that the chuck can be moved back and forth and rotated in the holding cylinder, and a tip end of the shaft cylinder is opened so that the tip of the slider protrudes from the tip of the shaft cylinder. A mechanical spring is provided between the slider and the chuck so as to urge the slider in the forward direction and urge the chuck in the backward direction, and a head is formed at the rear end of the slider. Head A front stopper and a rear stopper are provided in the shaft cylinder so as to abut and regulate the forward and backward movement of the slider, and abut against the front and rear stoppers and the respective contact surfaces of the slider head. In this case, a mechanical pencil is formed so that the cam portions are engaged with each other at the same time, and the pitch between the cam portions of the front stopper and the rear stopper is shifted so that the slider rotates when engaged.

  The present invention is configured as described above and accommodates a cylindrical holding cylinder having a tip diameter-enlarged portion whose diameter is gradually enlarged toward the front in a shaft cylinder so as to be movable back and forth, and urges the cylinder in a forward direction. Forming a chuck in which a plurality of independent chuck elements having core insertion grooves are combined in a cylindrical shape so as to surround the core, and holding the chuck by interposing a ball between the tip enlarged diameter portion and the outer surface of the chuck element Insert the slider with a core holding part into the cylinder so that it can be moved back and forth so that its tip protrudes from the tip of the shaft cylinder, and move the slider in the forward direction. A mechanical spring is provided between the slider and the chuck to bias the chuck in the backward direction, so that only the chuck and the ball can be rotated in the holding cylinder even when the core is held.A head is formed at the rear end of the slider, and a front stopper and a rear stopper are provided in the shaft cylinder so that the head abuts and regulates the forward and backward movement of the slider, and the front stopper and A cam portion is formed so as to engage with each contact surface of the rear stopper and the head of the slider, and the pitch of the cam portion of the front stopper and the rear stopper is shifted so that the slider rotates when engaged. Because when the slider is retracted by writing pressure during writing, and when the slider moves forward with the core away from the paper and comes into contact with each stopper, the engaging pitch of the cam portion is shifted. Rotates and the core rotates with it. As a result, the chuck holding the lead rotates following, but the chuck and the lead tank are not fixed as described above, and the chuck is rotatable in the holding cylinder, so the lead tank etc. The core can be freely rotated by rotating the slider. Since this chuck mechanism is almost the same as the mechanism employed in the conventional auto-sharp mechanism that automatically feeds the lead, the structure is simple and the assembly is easy and economical. .

  1 and 2 show an embodiment of the mechanical pencil of the present invention, and the basic configuration is substantially the same as the writing instrument described in Japanese Patent Application Laid-Open No. 2007-21843 according to the applicant's application. . That is, the shaft tube 1 is connected to the front shaft tube 4 provided with a grip on the outer periphery by attaching the taper 2 to the front end by screwing and fitting, and the rear portion of the front shaft tube 4 by screwing, fitting or the like. The rear shaft cylinder 5 is provided, an opening 6 is formed in the taper 2 of the front shaft cylinder 4, and a clip 7 is provided in the rear shaft cylinder 5. A core tank 8 is inserted into the shaft cylinder, and an eraser 9 and a knock cap 10 are attached to the rear end of the core tank. In the present invention, “front” refers to the direction in which the lead is drawn (downward in FIG. 1), and “rear” refers to the opposite direction (upward in FIG. 1).

  The core tank 8 has an outer peripheral flange 11 at an intermediate portion, and a receiving ring 12 is fitted to the front thereof so as to be movable in the axial direction. The receiving flange 13 formed on the receiving ring 12 is connected to the front shaft cylinder. 4, a knock spring 14 is provided between the receiving flange 13 and the outer peripheral flange 11 of the core tank, and the outer peripheral flange 11 is in contact with the inner step portion 15 of the rear shaft cylinder 5. The lead tank 8 is urged rearward so as to be movable back and forth.

  A pipe holder 17 having a core supply pipe 16 is fixed to the tip of the core tank 8 and is inserted into a sleeve 18 provided in the shaft cylinder 1. The sleeve 18 is housed in a shaft cylinder so as to be movable back and forth, and is urged forward by a mechanical push spring 20 interposed between the sleeve 18 and a spring retainer 19 provided in the shaft cylinder, and a tip is formed in the shaft cylinder. It moves forward until it hits the projection 21 such as a rib, and retracts until the locking projection 22 formed on the outer periphery hits the locking projection 23 formed on the inner surface of the shaft tube. An annular groove 24 is formed on the outer periphery of the sleeve so as to receive the locking protrusion 23.

  Referring to FIG. 5, a rear portion of a holding cylinder 26 having an outer peripheral step portion 25 formed so that the tip of the sleeve 18 abuts is inserted into the sleeve 18, and the front portion of the holding cylinder 26 is the front shaft. It is slidably inserted into the inner surface of the cylinder 4. At the tip of the holding cylinder 26, a tip enlarged portion 27 whose inner diameter gradually increases toward the front is formed. In the embodiment shown in the drawing, the tip enlarged diameter portion 27 is formed with a metal material enlarged diameter ring 28 separately from the holding cylinder 26, and the enlarged diameter ring 28 is inserted and fixed to the holding cylinder 26. You may form an enlarged diameter part integrally with a holding cylinder. The rear end of the holding cylinder 26 is formed so as to be elastically expandable by forming a slit 29, and a sliding protrusion 30 is provided on the inner surface, and the sliding protrusion 30 is a peripheral surface of the pipe holder 17. It protrudes into the groove part 31 formed in. Therefore, when the lead tank 8 is knocked and the sliding projection 30 comes into contact with the groove edge at the rear of the groove portion 31, the holding cylinder 26 moves, and the tip of the diameter expanding ring 28 is inward of the front shaft cylinder 4. It advances to the position where it abuts on the stepped portion 32 (gap A in FIG. 2). Since the rear end portion of the holding cylinder 26 is formed so as to be expandable by the slit 29 even when the advancement of the holding cylinder 26 stops, the sliding protrusion 30 rides on the outer peripheral surface of the pipe holder 17 from the groove portion 31. In this state, the pipe holder 17 and the core supply pipe 16 are further advanced. When the knock is stopped and the lead tank 8 is moved backward by the action of the knock spring 14, the lead supply pipe 16, the pipe holder 17 and the holding cylinder 26 are also moved backward, and the sliding protrusion 30 enters the groove 31. In this way, core feeding can be performed by a knocking operation as is well known.

  As shown in FIG. 6, a chuck 37 configured by combining a plurality of independent chuck elements 35 having core insertion grooves 34 into a cylindrical shape so as to surround the core 36 is inserted into the holding cylinder 26. A ball 38 is interposed between the outer diameter surface of the tip enlarged portion 27 and the chuck element 35, whereby the chuck 37 is held in the holding cylinder 26 so as to be able to move back and forth and rotate. The chuck element 35 is prevented from coming off by the projection 39 formed on the outer periphery of the rear end of the chuck element 35 coming into contact with the inner projection 40 in the holding cylinder, and the core supply pipe 16 is combined with this chuck element. 35 is inserted into the chuck from behind. The core 36 sent from the core supply pipe 16 enters the core insertion groove 34 of the chuck element 35, and when the chuck element 35 is retracted to a position corresponding to the narrow portion of the tip enlarged diameter portion 27 via the ball 38. Since the chuck element is fastened, it is strongly held to withstand the writing pressure. In this state, since the chuck element 35 is only held by the ball 38, the chuck element 35 can be freely rotated in the circumferential direction by rolling the ball. Further, as described above, when the lead tank 8 is advanced by the knocking operation and the chuck 37 is advanced together with the holding cylinder 26, the tip of the lead supply pipe 16 is held at the chuck element 35 even if the movement of the holding cylinder 26 is stopped halfway. Since only the chuck 37 can be moved forward by hitting the inner step portion, the ball 38 corresponds to a wide portion of the tip enlarged diameter portion 27, the chuck element 35 is loosened, and the core 36 is The lead can be extended to the forward position by releasing the holding.

  A slider 42 having a core holding portion 41 is provided at the tip opening 6 of the taper 2 so as to be movable in the front-rear direction. A cylindrical portion 43 is formed at the front portion of the slider 42 so as to pass through the opening, and a head portion 44 having an outer diameter larger than that of the cylindrical portion 43 is provided at the rear end. An elastic body (breaker rubber) such as rubber formed separately from the slider in the embodiment shown in the figure is fixed to the head portion 44 as a core holding portion 41. A piece may be provided to hold the core (not shown). A mechanical spring 45 is provided between the slider 42 and the chuck 37 so as to urge the slider 42 in the forward direction and urge the chuck 37 in the backward direction. In the embodiment shown in the figure, the mechanical spring 45 is constituted by one coil spring, but two springs may be provided so as to urge the slider and the chuck, respectively. The load relationship between the mechanical push spushing 20 and the mechanical spring 45 is a relationship of mechanical spring <mechanical push spring (the mechanical push spring has a stronger load than the mechanical spring).

  A front stopper 48 and a rear stopper 49 are provided in the shaft cylinder 1 so that the front surface 46 and the rear surface 47 of the head portion 44 are in contact with each other to restrict the forward and backward movements of the slider 42. In the embodiment shown in the figure, the front stopper 8 is an inner step portion 50 formed in the taper 2, and the rear stopper 49 is constituted by a stopper ring 51 fixed in the shaft cylinder. The stopper and the rear stopper can be provided at appropriate positions in the shaft cylinder. The stopper ring 51 has a locking projection (not shown) on its outer periphery, and is fixed in a detent state by engaging the locking projection with a locking groove (not shown) formed in the taper. Yes. In FIG. 2, the rearward movement amount of the slider 41 is the distance until the rear surface 47 of the head 44 of the slider 41 abuts against the rear stopper 49, and the gap B in FIG.

  Cam portions 52 and 53 are formed on the contact surfaces of the front stopper 48 and the rear stopper 49 and the front surface 46 and the rear surface 47 of the head portion 44 of the slider 42 so as to be engaged with each other when contacted. Although this cam portion can be appropriately configured, it is necessary to provide the cam portion 52 on the front stopper 48 side and the cam portion 53 on the rear stopper 49 side so as to be shifted so that the slider 42 rotates when engaged. . In the embodiment shown in FIG. 1, as shown in FIG. 7, an upright wall a extending in the axial direction of the slider 42 and an inclined wall b that connects the lower end of the upright wall a and the upper end of the adjacent upright wall a. The cam portions 52 and 53 are formed, and the positions of the standing wall a of the cam portion 52 on the front stopper side and the standing wall a of the cam portion 53 on the rear stopper side are shifted by a half pitch in the circumferential direction. In the figure, the above-mentioned standing wall is provided along the axial direction of the slider, but it can also be provided with an inclination, or by changing the shape and structure of the cam portion on the front stopper side and the rear stopper side. Also good.

  With the above configuration, if the knock cap 10 at the rear end of the lead tank 8 is knocked, the lead tank moves forward as shown by a chain line in FIG. 1, and the chuck 37 is combined with the chuck element 35 as described above. When the tip of the enlarged diameter ring 28 comes into contact with the inner step portion 32, the chuck element 35 is released, and the lead held by the lead holding portion 41 of the slider 42 moves to the advanced position. . If the knocking is stopped, the lead tank 8 is moved backward by the knock spring 14 and the chuck 37 is also moved back into the holding cylinder 26 to fasten the lead 36. Then, when writing pressure is applied to the tip of the lead and the lead moves backward, the slider 42 holding the lead by the lead holding part 41 also moves backward together with the lead, and accordingly the chuck 37 is held via the mechanical spring 45. The cylinder 26 and the sleeve 18 are retracted, the locking projections 22 and 23 are brought into contact with each other, the backward movement is prevented, and the writing pressure can be resisted and written.

  Referring to FIG. 8, when not in use, the slider 42 is linearly moved in the direction of the arrow 54 in FIG. 8B due to the writing pressure from the state where the front stopper 48 and the head portion 44 of the slider 42 are in contact with each other. The head 44 comes into contact with the rear stopper 49 in this state. In this state, the pitch of the cam portion 52 on the front stopper 48 side and the cam portion 53 on the rear stopper 49 side is shifted. The cam portion 53 formed on the contact surface of the head rear surface 47 does not mesh as it is. However, the backward movement continues, and the cam portion is formed with the inclined surface b. Therefore, the slider 42 rotates as shown by the arrow 55 in FIG. The cam part 53 meshes. Therefore, the lead held by the lead holding part 41 of the slider 42 rotates, and writing can be performed in this state. Then, when writing is stopped, the slider 42 moves forward as indicated by an arrow 56 in (D) by the action of the mechanical push spring 20 and the mechanical spring 45. Also at this time, since the pitch of the cam portion 52 on the front stopper 48 side and the cam portion 53 on the rear stopper 49 side is shifted, the slider 42 rotates while sliding on the inclined surface b as shown by the arrow 57 in FIG. Then, the core 36 can be rotated. In this way, since the tip of the lead rotates, it is possible to prevent the lead from being reduced and to write smoothly.

Sectional drawing which shows one Example of this invention. Sectional drawing which expands and shows a part of FIG. A partial enlarged sectional view at the time of writing. A partial enlarged sectional view at the time of knocking. Explanatory drawing which shows the relationship between a sleeve, a holding cylinder, and a chuck | zipper. The perspective view of a chuck | zipper element. Explanatory drawing of a cam part. Explanatory drawing which shows operation | movement of a cam part.

Explanation of symbols

1 Shaft 2 Taper 4 Front Shaft 5 Back Shaft 8 Core Tank 14 Knock Spring 16 Core Supply Pipe 17 Pipe Holder 18 Sleeve 19 Spring Presser 20 Mechanical Push Spring 26 Holding Tube 27 Tip Expanded Portion 28 Expanded Ring 35 Chuck Element 37 Chuck 38 Ball 41 Core holding part 42 Slider 44 Head 45 Mechanical spring 48 Front stopper 49 Rear stoppers 52 and 53 Cam part

Claims (4)

  A plurality of independent chucks each having a core insertion groove that accommodates a cylindrical holding cylinder having a tip enlarged portion whose inner diameter gradually increases toward the front in a shaft cylinder so as to be movable back and forth and urged in a forward direction. A chuck is formed in which the elements are combined in a cylindrical shape so as to surround the core, and a ball is interposed between the tip enlarged diameter portion and the outer surface of the chuck element, and the chuck is inserted into the holding cylinder so as to move back and forth and rotate. The slider having the core holding portion is inserted into the opening of the shaft tube so that the tip of the slider protrudes from the tip of the shaft tube so as to move back and forth, and the slider is urged in the forward direction and the chuck is attached in the backward direction. A mechanical spring is provided between the slider and the chuck so as to be biased, a head is formed at the rear end of the slider, and a front stopper is provided in the shaft cylinder so that the head abuts to regulate the forward and backward movement of the slider. Oh And a rear stopper, and a cam portion is formed so as to engage with each of the contact surfaces of the front and rear stoppers and the head of the slider, and the slider rotates when engaged. Mechanical pencil with a different pitch between the cam part of the stopper and the rear stopper.   2. The mechanical pencil according to claim 1, wherein the front stopper is an inward step formed in a taper provided at the tip of the shaft cylinder, and the rear stopper is a stopper ring provided in the shaft cylinder.   A sleeve is fitted on the outside of the rear end of the holding cylinder, a locking projection is provided on the inner surface of the sleeve and the shaft cylinder to restrict the backward movement of the sleeve, and a mechanical push spring that urges the sleeve in the forward direction. The mechanical pencil according to claim 1 or 2, wherein   A pipe holder connected to a lead tank is inserted inside the rear end of the holding cylinder, and a lead supply pipe is provided at the tip of the pipe holder so as to be inserted between the chuck elements combined in a cylindrical shape. The mechanical pencil according to any one of claims 1 to 3.

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