JP6256151B2 - mechanical pencil - Google Patents

Description

  The present invention is a mechanical pencil using a chuck body that allows advancement of the lead but prevents retraction of the lead, and is a cylinder, from the end of the cylinder toward the center so that the end can be expanded. At least two slits are provided, and an elastic piece portion that can be expanded by the slit is formed. The elastic piece portion engages with a groove portion of a member that presses the chuck body and engages a side surface of the member that presses the chuck body. The present invention relates to a mechanical pencil that incorporates a locking tool in which an engaging projection is formed.

Conventionally, in a mechanical pencil that uses a chuck body that allows the lead to move forward but prevents the lead from moving backward, in order to feed the lead with the rear end knock, the internal parts that move back and forth when knocked are moved forward. It is necessary to change the relative positional relationship at the time of retreating, and a part having a structure in which a slit or a notch is formed so that a part of a cylinder is expanded is known as a part for that purpose. As an example, two slits are provided at a constant width from the rear end side of the cylinder toward the front end side so that the rear end can be expanded, and can be expanded by this slit. There is a component having a structure in which an elastic piece portion is formed with a constant thickness, and an engagement protrusion for engaging and connecting with a groove portion of another member inserted into the cylinder is arranged on the inner surface of the elastic piece portion (special feature). No. 2007-21966 (Patent Document 1))
By forming the elastic piece portion in this way, the state in which the groove portion of another member included by the engagement protrusion is engaged and the other member that is expanded and released from the engagement of the elastic piece portion are locked. It is possible to change the relative positional relationship between the two parts when moving forward and when moving backward.

  In Patent Document 1, an automatic mechanical pen is used in which a lead is automatically drawn out using a ball chuck mechanism, and the assembly work is facilitated by sequentially assembling unit bodies.

JP 2007-21966 A

  However, in the prior art described in Patent Document 1, when knocking, a load is applied at one time to expand the elastic piece and the engagement protrusion crosses the step of the engagement groove to release the engagement. , Knock was heavy and it made me feel uncomfortable. In addition, if the slit width is extended over the entire length to reduce the load over which the engagement protrusion gets over the step of the engagement groove, or if the thickness of the entire elastic piece is reduced, the locking load after the expansion will also decrease. The other member included cannot be securely locked, and the relative positional relationship between the two parts cannot be changed during advancement and retraction, so that there is a possibility that the lead cannot be extended.

  The present invention has been made in view of the above problems, and is a cylinder in a mechanical pencil that uses a chuck body that allows the lead to advance but prevents the lead from retreating, and its end can be expanded. In this way, at least two slits are provided from the end of the cylinder toward the center, and an elastic piece that can be expanded is formed by the slit. The elastic piece has an engagement groove for a member that presses the chuck body. A locking tool having an engaging projection for locking the side surface of the member that presses the engaging and chucking body is incorporated, and the width of the slit is made wider at the end than the slit bottom and / or The gist is that the thickness of the elastic piece is thinner at the end than at the slit bottom.

  The present invention is a mechanical pencil using a chuck body that allows advancement of the lead but prevents retraction of the lead, and is a cylinder, from the end of the cylinder toward the center so that the end can be expanded. At least two slits are provided, and an elastic piece part that can be expanded by the slits is formed. The elastic piece part is engaged with the engagement groove of the member that presses the chuck body and the side surface of the member that presses the chuck body. Incorporates a locking tool formed with a locking projection, and the slit has a wider width at the end than the slit bottom and / or the elastic piece has a wall thickness from the slit bottom side. Since the part has been made thinner, when the knocking operation is performed to push out the core by pressing the chuck body, the part having the engagement protrusion of the elastic piece part is bent first, so it is easy to expand and press the chuck body. With the engaging groove of the member to be Since the joint can be released with a light force, the feeling of knocking is improved, and when the expansion is further expanded, the expansion support portion of the elastic piece is bent, so that a strong reaction force is generated and the engagement with the member that presses the chuck body is achieved. Since it can be realized, the writing core can be reliably fed out. Furthermore, since the stress generated in the elastic piece portion at the time of the expanded locking can be dispersed, a mechanical pencil that is resistant to fatigue due to repeated knocking operations, has good stability over time, and has good feeding of the writing core is provided. be able to.

It is an external view of the whole product of 1st Example. It is an external view at the time of rotating 90 degree | times to the circumferential direction from the state of FIG. It is an external view at the time of rotating 180 degree | times to the circumferential direction from the state of FIG. It is a longitudinal cross-sectional view of the whole product of FIG. It is a front-end | tip part enlarged view in FIG. It is a front-end | tip part enlarged view of the latching tool in FIG. It is a front-end | tip part enlarged view of the latching state in FIG. It is an external appearance perspective view of the locking tool of 1st Example. It is a half cross-sectional view of the locking tool of the first embodiment. It is an external appearance perspective view of the relay member of 1st Example. It is a half sectional view of a locking tool of Modification 1 in the first embodiment. It is a half sectional view of a locking tool of Modification 2 in the first embodiment. It is a longitudinal cross-sectional view of the whole product of 2nd Example. It is a front-end | tip part enlarged view in FIG. It is a front-end | tip part enlarged view of the latching state in FIG. It is an external appearance perspective view of the locking tool of 2nd Example. It is a semi-sectional view of the locking tool of the second embodiment. FIG. 16 is an enlarged view of the vicinity of the engaging protrusion when the locking tool in FIG. 15 is locked. It is a half sectional view of a locking tool of Modification 1 in the second embodiment.

  The present invention is a mechanical pencil using a chuck body that allows advancement of the lead but prevents retraction of the lead, and is a cylinder, from the end of the cylinder toward the center so that the end can be expanded. At least two slits are provided, and an elastic piece portion that can be expanded by the slit is formed. The elastic piece portion engages with a groove portion of a member that presses the chuck body and engages a side surface of the member that presses the chuck body. And a slit having a wider width at the end than the slit bottom and / or a thickness of the elastic piece at the end from the slit bottom. When the knocking operation is performed to push out the core by pressing the chuck body, the part having the engagement protrusion of the elastic piece portion is bent first, so that the member is easy to expand and presses the chuck body. Engagement with the groove of Because it can be released with a large force, the feeling of knocking is improved, and when the expansion is further expanded, the expansion support portion of the elastic piece is bent, so that a strong reaction force is generated, and the engagement with the member that presses the chuck body can be realized. Therefore, it is possible to reliably feed out the writing core. Furthermore, since the stress generated in the elastic piece portion at the time of the expanded locking can be dispersed, a mechanical pencil that is resistant to fatigue due to repeated knocking operations, has good stability over time, and has good feeding of the writing core is provided. be able to.

  The locking tool is a cylinder, and at least two slits are provided from the end of the cylinder toward the center so that the end can be expanded, and an elastic piece that can be expanded is formed by the slit, The elastic piece part is formed with an engaging groove of a member that presses the chuck body, and an engaging projection that engages the side surface of the member that presses the chuck body when engaging and expanding the elastic piece part.

  The portion of the elastic piece that forms the engagement protrusion is easy to expand, and during the expansion, a strong reaction force is generated in the expansion support portion of the elastic piece, and the stress generated in the elastic piece during expansion is dispersed. As a means for this, there is a method in which the width of the slit is made wider than the bottom of the slit, or the thickness of the elastic piece is made thinner than the expansion support part in the elastic piece on the slit bottom side. Can be mentioned. The change in the width and / or thickness may be constituted by two or more steps or may be changed continuously. Also, when forming the stepped portion, the corners formed at the slit bottom and stepped portion are chamfered or rounded to relieve stress concentration during expansion and prevent breakage of the locking tool. be able to.

  The engaging protrusion formed on the elastic piece has a substantially trapezoidal shape having a flat surface at the apex, and the engaging groove provided on the outer peripheral surface of the relay member that presses the chuck body is formed on the engaging protrusion. The opening has a substantially triangular shape whose opening is longer than the length of the flat portion in the component axis direction. By forming the engagement protrusion and the engagement groove in this manner, the engagement protrusion can easily enter the engagement groove, and the engagement protrusion outer surface and the engagement groove inner surface can be brought into close contact with each other. The backlash can be reduced. Not limited to this, the load at the time of molding to a die or cutting tool by making the apex of the engagement protrusion R-shaped, forming a flat part at the apex of the engagement groove, or making the apex R-shaped, etc. Can increase productivity. That is, each shape can be selected as appropriate as long as the engaging tool and the engaging member can be engaged by the engaging protrusion and the engaging groove.

  The engaging projection formed on the elastic piece is formed to have a substantially trapezoidal shape having a flat surface at the apex. By forming the engagement protrusions in this way, the flow of the material at the time of molding in the engagement protrusions can be made smooth, and the residual stress remaining on the engagement protrusions after molding can be reduced, so it is resistant to fatigue due to repeated disengagement. , A product with good stability over time can be provided. In addition, when the engagement protrusion gets over the step of the relay member engagement groove in order to open the elastic piece and release the engagement between the locking member and the relay member by knocking, the engagement protrusion is substantially trapezoidal. And by making the part which touches the level | step difference of a relay member engagement groove into an inclined surface, the force which expands gradually to an elastic piece part is added, and an elastic piece part can be expanded smoothly. Not limited to this, the elastic piece portion can be more smoothly expanded by reducing the inclination angle of the trapezoid-shaped inclined surface in contact with the step, particularly by making the rear end side smaller than the front end side of the elastic piece portion. . Further, the angle of the inclined surface on the rear end side of the elastic piece portion of the substantially trapezoidal engagement protrusion is formed to be equal to the inclined angle after the elastic piece portion is expanded, so that the outer peripheral side surface of the relay member is expanded when the elastic piece portion is expanded. The stress applied to the engaging protrusions that come into contact with each other is distributed over the entire inclined surface, so that the load caused by repeated use can be reduced, and a product with good temporal stability can be provided.

  The material of the locking tool is not particularly limited as long as it can form an expandable elastic piece. Desirably, a material having a Young's modulus of 1.0 GPa or more and less than 10.0 GPa is preferably used. When the material has a modulus of less than 1.0 GPa, the elasticity of the elastic piece portion is weak, and the enclosing relay member can be reliably locked. Therefore, there is a possibility that the lead cannot be extended. In the case of 10.0 GPa or more, the elasticity of the elastic piece portion is strong, and the load over which the engaging protrusion gets over the stepped portion of the relay member engaging groove increases, so that the knocking feeling may be deteriorated. Specific examples of the material having the Young's modulus include polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), polyethylene resin (PE), polypropylene resin (PP), polystyrene resin (PS), acrylonitrile styrene resin ( AS), acrylonitrile styrene butadiene resin (ABS), methacrylic resin (PMMA), polyacetal resin (POM), polyamide resin (PA), polycarbonate resin (PC), and polyethylene terephthalate resin (PET). Not limited to this example, any material having the above-described Young's modulus can be used as appropriate.

  When polyacetal resin (POM) is used as the material of the locking tool, the locking tool and the relay member are different from each other, such as using polypropylene resin (PP) as the material of the relay member included in the locking tool. By using the material, it is possible to reduce the wear of the sliding parts such as the engaging protrusions, engaging grooves, and their surroundings, so the load due to repeated use can be reduced, and a product with good stability over time is provided. be able to. Further, in addition to the above, the outer surface of the sliding portion may be subjected to a textured process or a lubricant may be applied to reduce wear.

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

  A front member 5 having a slider 4 that is slid forward and backward is urged forward by a front end ring 2 and a front end spring 3 that are press-fitted and fixed inside. It is connected to the shaft cylinder body 8 constituted by screwing. A core feeding unit 9 is arranged in the shaft cylinder body 8 so as to be urged forward by a cushion spring 10, and the cushion spring 10 expands and contracts when a high writing pressure is applied during use, and an impact on the writing core L Has eased. A clip 12 is fitted into a reduced diameter portion 11 formed at the rear of the rear shaft 7.

  The slider 4 has a stainless steel pipe 13 on the front and a core holding member 14 press-fitted on the inside, and an O-ring 15 is mounted on the outside. When writing, even when the pipe 13 touches the paper surface due to the wear of the writing core L, the pipe 13 is pushed against the paper surface by the writing pressure along with the writing core wear due to writing, so that the writing can be continued. When the pipe 13 is separated from the paper surface, the slider 4 advances by the tip spring 3. The writing core L held by the core holding member 14 when the slider 4 moves forward by the tip spring 3 is used in combination with a chuck body 19 that can grip the core so as to allow advancement of the core, which will be described later, but prevent retraction. Can always be pulled out to the tip of the pipe 13, so that the writing core L can maintain the writing state without changing and knocking the rear end pressing member 40, so that continuous writing is possible. Further, when carrying, the slider 4 can be fitted into the tip ring 2 by the O-ring 15 to stop the forward / backward movement, thereby preventing unexpected centering. When it is used again, the slider 4 moves forward by pressing the rear end of the slider 4 by the lead feeding unit 9 and releasing the fitting of the O-ring 15 so that writing is possible.

  As described above, the front end surface of the writing core is substantially in the same position as the front end surface of the pipe, or the writing core that originally protruded from the front end surface of the pipe is worn, so that the front end surface of the writing core is the front end surface of the pipe. Even in the substantially same position, the pipe is pushed against the paper surface by the writing pressure along with the wear of the core due to the writing, so that the writing can be continued. This configuration is particularly effective when the core diameter of the writing core is small, specifically for cores having a nominal diameter of 0.3 mm, 0.2 mm or less. It is possible to write with the writing core guided by the pipe without protruding from the pipe, preventing changes in writing pressure during writing and even if the writing core gets caught on the paper surface. be able to.

  The lead feeding unit 9 has a chuck set 16 at the front, and the chuck set 16 is provided with a ring 17 for forming a tapered portion 18 whose diameter increases toward the front. A chuck body 19 having 41 is arranged, and a ball 22 is inserted between the taper portion 18 and a ball receiving seat 20 formed on the chuck body 19. Further, the chuck body 19 is urged rearward by a chuck spring 23 disposed between the flange portion 21 formed at the rear end of the chuck body 19 and the inner stage of the ring. Thus, a rust effect is generated through the ball 22 and the lead can be allowed to advance but the retract can be prevented. A chuck stopper 24 is fixed by caulking in front of the ring 17 so that the chuck body 19 and the ball 22 do not fall off.

  On the rear side of the chuck set 16, there is press-fitted a locking tool 25 having an elastic piece portion 26 formed with a substantially trapezoidal locking protrusion 27 having a flat portion 28 at the apex, and having a rear end that can be expanded. ing. A large diameter portion 30 is formed at the front end inside the locking tool 25, the rear end surface of the large diameter portion 30 and the front end surface of the locking tool are brought into contact with each other, and the engagement protrusion 27 is engaged with the rear outer peripheral surface. The relay member 29 having a substantially triangular engagement groove 31 having an opening 32 longer than the length in the component axial direction of the flat portion 28 formed on the engagement protrusion 27 is included. By arranging a core guide pipe 34 having one or more writing cores through which the inner diameter is inserted and less than two inside the relay member 29, a core tank 35 press-fitted to the rear of the relay member 29 to store the writing core L, The writing core L can be reliably inserted to the chuck body 19. Further, by providing the core insertion hole 33 so that only one writing core passes between the core guide pipe 34 and the core tank 35 behind the relay member 29 and is smaller than the inner diameter of the core guide pipe 34. Only one writing lead can be reliably inserted from the lead tank 35 to the lead guide pipe 34. The chuck set 16, the locking member 25, and the relay member 29 are urged rearward by a knock spring 37 disposed between the core tank 35 and the core 36 via the core 36. An eraser receiving member 38 is press-fitted to the rear end of the lead tank 35, and an eraser 39 and a pressing member 40 are detachably attached to the eraser receiving member 38.

Next, the core feeding operation by knocking the rear end pressing member 40 will be described.
When the first writing core L is drawn out, the writing core L stored in the core tank 35 is dropped to the core biting portion 41 of the chuck body 19 by its own weight by first orienting the front of the shaft cylinder in the direction of gravity. By providing the core insertion hole 33 formed in the core guide pipe 34 and the relay member 29 as described above, one writing core L can be reliably inserted to the core biting portion 41 of the chuck body 19.

  Next, when the pressing member 40 starts to be knocked in the forward direction of the shaft cylinder 1, the relay member 29 press-fitted in front of the lead tank moves forward together with the lead tank 35. At this time, the engagement groove 31 formed in the relay member 29 and the engagement protrusion 27 formed on the inner surface of the elastic piece portion 26 in the engagement tool 25 are in an engaged state. The chuck set 16 that is press-fitted and fixed to the front end of 25 is advanced as a relay member until the front end of the chuck set 16 contacts the rear end of the tip ring 2. If the slider 4 is in the retracted state at this time, the front end of the chuck set 16 comes into contact with the rear end of the slider 4 and pushes the slider 4 forward, so that the O-ring 15 fitted inside the tip ring 2 is fitted. The slider 4 is urged forward by the elastic force of the tip spring 3.

  Even if the front end of the chuck set 16 comes into contact with the rear end of the tip ring 2 and the movement of the locking tool 25 and the chuck set 16 stops, the rear end of the locking tool 25 can be expanded. The elastic piece 26 in the locking tool 25 is bent outward by a load (hereinafter referred to as a knock load) that knocks the pressing member 40 in the forward direction of the shaft cylinder 1, and the engagement with the relay member 29 is released. Only the relay member 29 can be moved forward, and the locking tool 25 and the chuck set 16 are stopped. However, the relative movement difference that the lead tank 35 and the relay member 29 move forward can be given.

  When the knocking is continued, the rear end of the chuck body 19 is pressed by the front end of the relay member 29 and the chuck body 19 is advanced to expand the core engaging portion 41 of the chuck body 19. The core holding member 14 falls by its own weight to the rear end of the core holding portion 42. The advancement of the relay member 29 and the lead tank 35 by knocking ends when the lead end of the lead tank 35 and the rear end of the locking tool 25 come into contact with each other.

  When the pressing to the pressing member 40 is released, the relay member 29 and the core tank 35 are moved backward by the knock spring 37. At this time, since the relay member 29 is clamped by the elastic piece portion 26 of the locking tool 25, the relay member 29 and the locking tool 25 are in a locked state, and the locking tool 25 is in the inner stage of the core 36. Until the movement stops, the relay member 29, the locking member 25, and the chuck set 16 are retreated as a single body. Until the locking tool 25 comes into contact with the inner stage of the core 36, the chuck body 19 is pressed and expanded by the relay member 29.

  After the latching tool 25 comes into contact with the inner stage of the core 36, the relay member 29 and the lead tank 35 are retracted, so that the pressure on the chuck body 19 is also released, and the chuck body 19 is closed by the chuck spring 23, and the wedge effect is obtained. Since this occurs, the core is engaged. Thereafter, the relay member 29 and the core tank 35 are further retracted, and the engagement groove 31 formed in the relay member 29 and the engagement protrusion 27 formed on the inner surface of the elastic piece portion 26 in the locking tool 25 are again engaged. At the same time, the rear end of the large-diameter portion 30 of the relay member 29 comes into contact with the front end of the locking tool 25, and all the retreating is completed.

  Here, the locking force in the locked state of the relay member 29 and the locking tool 25 is based on the load generated by the weight of the chuck set 16 and the weight of the locking tool 25 when the front of the shaft cylinder 1 is directed in the direction of gravity. If it is weak and insufficient, only the relay member 29 and the lead tank 35 are retracted before the locking tool 25 and the chuck set 16 are retracted, and the chuck body 19 is also retracted at the same time. It becomes a state. After that, the rear end of the large-diameter portion 30 of the relay member 29 comes into contact with the front end of the locking tool 25 and the locking tool 25 and the chuck set 16 start to move backward, but the writing core L is gripped by the chuck body 19. Retreat as a unit. That is, a gap is generated between the tip of the writing core L and the core holding member 14 by the distance until the locking tool 25 comes into contact with the inner stage of the core 36 and the retraction of the locking tool 25 and the chuck set 16 is completed. Therefore, it takes time to feed out the writing core L. In addition, when the lead feeding amount is shorter than the gap due to variations in parts dimensions or assembly, the writing lead L cannot be inserted into the lead holding member 14, and the lead cannot be drawn. End up.

  Thereafter, the lead feeding operation by knocking is performed again, and the chuck body 19 in the lead-engaged state is advanced together with the chuck set 16 in a state in which the locking tool 25 and the relay member 29 are engaged, whereby the lead-holding member 14 is moved to the lead-holding member 14. L is inserted, and the chuck body 19 is further advanced by utilizing the difference in the relative movement of the locking member 25, the relay member 29 and the core tank 35 due to the disengagement between the locking member 25 and the relay member 29. After the chuck body 19 is expanded, the relay member 29 and the locking member 25 are retracted while being in the locked state, so that the chuck set 16 is retracted while maintaining the expanded state of the chuck body 19. After the locking tool 25 comes into contact with the inner stage of the core 36, only the relay member 29 and the lead tank 35 are retracted, so that the pressure on the chuck body 19 is also released, and the chuck body 19 is closed by the chuck spring 23, and the lead core is again opened. The leading end of the writing core L remains in the advanced position in the core holding member 14, and thus approaches the writing enabled state.

  Here, when the engaging force in the engaged state of the relay member 29 and the locking tool 25 is weaker than the load of the knock spring 37 and is not sufficient, the engagement of the relay member 29 and the locking tool 25 is released at the stage of starting the knocking. As a result, the chuck set 16 cannot be moved forward, and the chuck body 19 is opened and closed without changing the position of the writing core L, so that the core cannot be extended.

  Furthermore, the locking force in the locked state of the relay member 29 and the locking tool 25 is greater than the load generated by the weight of the chuck set 16 and the weight of the locking tool 25 when the front of the shaft cylinder 1 is directed in the direction of gravity. If it is weak and not sufficient, only the relay member 29 and the core tank 35 are retracted before the locking tool 25 and the chuck set 16 are retracted, and the chuck body 19 is also retracted at the same time. It becomes. Thereafter, the rear end of the large-diameter portion 30 of the relay member 29 comes into contact with the front end of the locking tool 25 and the locking tool 25 and the chuck set 16 start to move backward, but the writing core L is held by the core holding member 14. Only the chuck body 19 moves backward together with the locking tool 25 and the chuck set 16 while staying at the forward position. That is, the writing core L is pulled out from the chuck body 19 by the distance until the locking tool 25 comes into contact with the inner stage of the core 36 and the backward movement of the locking tool 25 and the chuck set 16 is completed. Wear powder is generated by the wear of L. The generated wear powder adheres to the chuck body 19-core biting portion 41, and when it is generated and adhered in large quantities due to repeated knocking, the writing core L becomes slippery, and the chuck body 19 is written when the chuck set 16 advances. There is a possibility that the lead L cannot be gripped and the lead cannot be fed out. In addition, the writing core may not withstand the writing pressure during writing and the writing core may retract.

  In the above-described center feeding operation by knocking the rear end pressing member 40, the locking tool 25 plays a role of making a relative movement difference between the chuck set 16 and the relay member 29 by the forward and backward movement of the core feeding unit 9. Furthermore, the influence on the knocking feeling during the feeding operation is great.

  More specifically, when the pressing member 40 starts to be knocked in the forward direction of the shaft cylinder 1, the relay member 29 press-fitted in front of the core tank 35 also moves forward together with the core tank 35. At this time, the engagement groove 31 formed in the relay member 29 and the engagement protrusion 27 formed on the inner surface of the elastic piece portion 26 in the engagement tool 25 are in an engaged state. The chuck set 16 that is press-fitted and fixed to the front end of 25 is advanced in the same manner as the relay member 29 until the front end of the chuck set 16 comes into contact with the rear end of the tip ring 2. Here, the engaging force required for the locking tool 25 needs to be stronger than the load of the knock spring 27. As described above, if the engagement force is weaker than the load of the knock spring 27, the engagement is disengaged at the stage of knocking, and the chuck set 16 cannot move forward together with the relay member 29, and the writing core L is It becomes impossible to pay out. At this stage, the elastic piece portion 26 in the locking tool 25 is in a closed state, and is the same body as the relay member 29 and in an engaged state. Further, the knock load is only the load of the knock spring 37.

  Next, the front end of the chuck set 16 comes into contact with the rear end of the tip ring 2, and the movement of the locking tool 25 and the chuck set 16 is stopped. Further, when the knocking is continued and the knock load exceeds the engaging force of the locking device 25, the elastic piece portion 26 formed on the locking device 25 generates a force that bends outward. 25, the rear end is widened, and the engagement protrusion 27 formed on the inner surface of the elastic piece 26 passes over the engagement groove 31 formed in the relay member 29, and the engagement is released. Only the core tank 35 and the relay member 29 are released. Advances are possible. At this stage, the elastic piece portion 26 in the locking tool 25 has shifted from the closed state to the expanded state. In addition to the load of the knock spring 37, a load for expanding the elastic piece 26 is added to the knock load. That is, a sudden increase in knock load can be avoided by minimizing the load for expanding the elastic piece 26, leading to an improvement in the knock feeling.

  If the knocking is continued further, only the lead tank 35 and the relay member 29 can be advanced in a state in which the engagement by the locking tool 25 is released, and the rear end of the chuck body 19 is pressed by the front end of the relay member 29, The core biting portion 41 of the chuck body 19 can be expanded by advancing 19. The advancement of the relay member 29 and the lead tank 35 by knocking ends when the lead end of the lead tank 35 and the rear end of the locking tool 25 come into contact with each other. At this stage, the elastic piece 26 in the locking tool 25 is in a completely expanded state, and the relative position of the elastic piece 26 changes with the relay member 29 until the knocking operation is completed. Further, although the relay member 29 is allowed to advance, the relay member 29 is held by the elastic piece portion 26. In addition to the load of the knock spring 37, a frictional resistance due to the elastic piece 26 sandwiching the relay member 29 is added to the knock load. By sandwiching the relay member 29 by the elastic piece portion 26 and generating a frictional resistance, a sudden decrease in knock load can be reduced from the load generated to expand the elastic piece portion 26, and the load change is small. A smooth knock feeling can be obtained.

  Next, when the pressing to the pressing member 40 is released, the relay member 29 and the core tank 35 are moved backward by the knock spring 37. At this time, the elastic piece portion 26 in the latching tool 25 is completely expanded, and the state where the relay member 29 is sandwiched continues, and the relay member 29 and the latching tool 25 are in the latched state. Therefore, the relay member 29, the locking tool 25, and the chuck set 16 remain in the same state with their relative positions changed from before the knocking until the locking tool 25 comes into contact with the inner stage of the core 36 and stops moving. To retreat. Here, the locking force required for the locking tool 25 needs to be stronger than the load generated by the own weight of the chuck set 16 and the own weight of the locking tool 25 when the front of the shaft cylinder 1 is directed in the direction of gravity. As described above, if the locking force is weaker than the load generated by the weight of the chuck set 16 and the weight of the locking tool 25, only the relay member 29 and the core tank 35 are moved before the locking tool 25 and the chuck set 16 are retracted. Since the chuck body 19 is also retracted at the same time, the lead is engaged before the locking tool 25 is completely retracted. There is a risk that problems such as impossibility and inability to withstand the writing pressure during writing will cause the core to retract.

  After the retracted locking tool 25 comes into contact with the inner stage of the core 36, only the relay member 29 and the core tank 35 are retracted, so that the pressure on the chuck body 19 is also released, and the chuck body 19 is closed by the chuck spring 23. Since the wedge effect is generated, the core is engaged. At this stage, the elastic piece portion 26 in the latching tool 25 is in a fully expanded state, and the relay member 29 and the relay member 29 are in a relative state until the relay member 29 and the lead tank 35 are completely retracted. The position changes. Further, the relay member 29 is allowed to move backward, but the relay member 29 is held by the elastic piece portion 26. That is, the frictional resistance caused by the elastic piece 26 sandwiching the relay member 29 needs to be weaker than the load that causes the relay member 29 and the core tank 35 to move backward by the knock spring 37.

  Finally, the relay member 29 and the core tank 35 are further retracted, and the engagement groove 31 formed in the relay member 29 and the engagement protrusion 27 formed on the inner surface of the elastic piece portion 26 in the locking tool 25 are engaged again. At the same time, the rear end of the large-diameter portion 30 of the relay member 29 comes into contact with the front end of the locking tool 25 and all the retreating is completed. At this stage, the elastic piece portion 26 in the locking tool 25 is in a closed state, and is the same body as the relay member 29 as in the initial stage.

  By repeating the knocking operation, the writing core L can pass through the core holding member 14 and can be fed out to the tip of the pipe 13 and beyond, so that writing is possible. When writing, the writing state can be maintained without knocking the rear end pressing member 40 by the back-and-forth movement of the slider 4 described above, so that continuous writing is possible. Further, when the remaining core state is reached, the remaining core can be discharged again by repeating the rear end pressing member 40 knocking operation, and the state can be returned to the writable state.

  In the locking device 25 of the first embodiment, two slits 43 are provided at opposite positions on the circumference from the rear end side of the cylinder toward the front end side so that the rear end can be expanded. An expandable elastic piece 26 is formed. The elastic piece portion 26 includes a first elastic piece portion 46 formed by a first slit portion 45 starting from an expansion support portion 44 that is a bottom portion of the slit 43, and a second slit portion 47 having a width wider than that of the first slit portion 45. The second elastic piece portion 48 is formed by an engaging projection 27 for engaging and connecting with the relay member 29 inserted into the cylinder. In this embodiment, the slit is formed from the rear end side of the locking tool. However, depending on the configuration of other parts, it can be formed from the front end side of the locking tool or in the intermediate portion. Further, although there are two slits, it is only necessary that the elastic piece can exert a load that changes the relative positional relationship between the locking tool and the relay member when the elastic piece is moving forward and backward, and the number thereof may be set as appropriate.

  By forming the slit 43 in this manner, the second elastic piece portion 48 is more easily bent than the first elastic piece portion 46, and therefore, at the initial stage of expansion, the second elastic piece portion 48 is bent first. Since the load over which the engagement protrusion 27 climbs over the step of the engagement groove 31 provided in the relay member 29 can be reduced, the resistance when knocking is reduced and the feeling of knocking is improved. As the expansion progresses, the first elastic piece portion 46 bends, so that the reaction force of the entire elastic piece portion 26 can be improved and the relay member 29 can be locked. Further, it is possible to disperse the stress generated at the time of spreading and spreading to the first elastic piece portion 46 and the second elastic piece portion 48, and to provide a product that is resistant to fatigue due to repeated disengagement and has good stability over time. Can do.

  In the present embodiment, the engagement protrusion 27 formed on the second elastic piece portion 48 has a substantially trapezoidal shape having a flat portion 28 at the apex, and the engagement groove 31 of the relay member 29 that presses the chuck body 19 is The opening portion 32 has a substantially triangular shape that is longer than the length of the flat portion 28 formed in the engaging protrusion 27 in the component axial direction. By forming the engagement protrusion 27 and the engagement groove 31 in this manner, the engagement protrusion 27 can easily enter the engagement groove 31, and the outer surface of the engagement protrusion 27 and the inner surface of the engagement groove 31 can be brought into close contact with each other. And play at the time of engagement can be reduced. Not limited to this, the apex of the engagement protrusion 27 is formed into an R shape, a flat portion is formed at the apex of the engagement groove 31, or the apex is formed into an R shape. Productivity can be improved. That is, it is only necessary that the locking tool 25 and the relay member 29 can be engaged by the engagement protrusion 27 and the engagement groove 31, and the respective shapes can be selected as appropriate.

  Further, the engagement protrusion 27 formed on the second elastic piece portion 48 is formed to have a substantially trapezoidal shape having a flat portion 28 at the apex. By forming the engagement protrusions 27 in this way, the flow of the material at the time of molding in the engagement protrusions 27 can be made smooth, the residual stress remaining in the engagement protrusions 27 after molding can be reduced, and repeated engagement release A product that is resistant to fatigue and has good stability over time can be provided. Further, when the engagement protrusion 27 gets over the step of the engagement groove 31 in the relay member 29 in order to knock and expand the elastic piece portion 27 to release the engagement between the locking member 25 and the relay member 29, By making the joint protrusion 27 into a substantially trapezoidal shape and making the portion of the relay member 29 in contact with the step of the engagement groove 31 as an inclined surface, a force of gradually expanding is applied to the elastic piece portion 26 so that the elastic piece portion 26 is smoothly smoothed. Can be expanded.

  As a first modification of the first embodiment, as shown in FIG. 11, the shape of the engagement protrusion on the cylindrical outer peripheral surface where the engagement protrusion 27 formed on the second elastic piece portion 48 of the locking tool 25 is disposed. It is also possible to form a groove portion 49 that is similar to that of the second elastic piece portion 48 so that the thickness in the second elastic piece portion 48 is substantially uniform. Since the second elastic piece portion 48 is more easily bent than the first elastic piece portion 46, the engagement protrusion 27 is provided on the relay member 29 when the second elastic piece portion 48 is bent first in the initial stage of expansion. Since the load over the step of the engaging groove 31 can be lowered, the resistance when knocking is reduced and the feeling of knocking is improved. As the expansion progresses, the first elastic piece portion 46 bends, so that the reaction force of the entire elastic piece portion 26 can be improved and the relay member 29 can be locked. Further, it is possible to disperse the stress generated at the time of spreading and spreading to the first elastic piece portion 46 and the second elastic piece portion 48, and to provide a product that is resistant to fatigue due to repeated disengagement and has good stability over time. In addition, since the thickness in the second elastic piece portion 48 is made uniform, sink marks generated on the outer peripheral surface of the cylinder where the protrusions are arranged at the time of molding can be prevented. Variations in shape can be suppressed.

  Furthermore, as a second modification of the first embodiment, as shown in FIG. 12, a slit 43 provided from the rear end side of the cylinder toward the front end side so that the rear end of the locking tool 25 can be expanded, An example will be given in which the slit 43 is formed by a series of curves that gradually expand from the expansion support portion 44 toward the rear end of the cylinder. Not limited to this, it may be formed by a series of straight lines that gradually expand from the expansion support portion 44 of the slit 43 toward the rear end of the cylinder, and extends from the expansion support portion 44 of the slit 43 toward the rear end of the cylinder. The same effect can be obtained by forming a series of slits 43.

  In the locking device 25 of Modification 2 in the first embodiment, two slits 43 are provided at facing positions on the circumference from the rear end side of the cylinder toward the front end side so that the rear end can be expanded, An elastic piece 26 that can be expanded by the slit 43 is formed. The elastic piece portion 26 is formed by a series of curves that gradually expand from the expansion support portion 44 of the slit 43 toward the rear end side of the cylinder, and a relay that is inserted into the cylinder on the inner surface near the rear end of the elastic piece portion 26. An engaging protrusion 27 for engaging and connecting with the member 29 is disposed.

  By forming the slit 43 in this manner, the vicinity of the engaging protrusion 27 forming portion is more easily bent than in the vicinity of the expanding support portion 44. By bending first, the load over which the engagement protrusion 27 gets over the step of the engagement groove 31 in the relay member 29 can be lowered, and the resistance when knocking is reduced, so that the knock feeling is improved. Further, as the expansion progresses, the vicinity of the expansion support portion 44 bends to improve the reaction force of the entire elastic piece portion 26, and the relay member 29 can be locked by the engagement protrusion 27, and a reliable core You can pay out. Further, the stress generated in the elastic piece portion 26 and the periphery thereof at the time of locking can be distributed from the vicinity of the expansion support portion 44 to the vicinity of the engagement protrusion 27 formation portion. Furthermore, by forming with a series of curves, the flow of material during molding can be improved, the residual stress can be reduced, and a product that is resistant to fatigue due to repeated unlocking and is stable over time can be provided.

  A second embodiment of the present invention will be described with reference to FIGS. In the locking device 25 of the second embodiment, the outer diameter of the portion where the elastic piece portion 26 is formed is the same, and the inner diameter at the distal end side of the elastic piece portion 26 is larger than the inner diameter of the elastic piece portion 26 expansion support portion 44 side. By slightly increasing the size, it is a locking device 25 in which the cross-sectional thickness of the elastic piece portion 26 in the cylindrical axis direction has changed, and the rear end side of the cylinder is expanded from the rear end side so that the rear end of the locking device 25 can be expanded. Two slits 43 having a length exceeding the thickness changing portion and having a constant width are provided at two positions facing each other on the circumference, and an elastic piece 26 which can be expanded by the slit 43 is formed. The elastic piece portion 26 is composed of a thick portion 50 starting from the widening support portion 44 of the slit 43 and a thin portion 51 having a reduced thickness on the rear end side. The thin portion 51 has an inner surface inserted into a cylinder. An engaging protrusion 27 for engaging and connecting with the member 29 is disposed.

  By forming the elastic piece portion 26 in this manner, the thin portion 51 is more easily bent than the thick portion 50, and further, the initial expansion of the elastic piece portion 26 is reduced by reducing the thickness in the deformation direction. Since the thin portion 51 is bent first, and the load over which the engaging protrusion 27 gets over the step of the engaging groove 31 provided in the relay member 29 can be lowered, the resistance when knocking is reduced and the feeling of knocking is improved. . Further, as the expansion progresses, the thick portion 50 is bent, so that the reaction force of the entire elastic piece portion 26 is improved and the relay member 29 can be locked, so that the lead can be reliably fed out. Moreover, the stress generated at the time of spreading and locking can be distributed to the thick portion 50 and the thin portion 51, and a product that is resistant to fatigue due to repeated disengagement and has good temporal stability can be provided.

  In the present embodiment, the engagement protrusion 27 formed on the elastic piece portion 26 is formed to have a substantially trapezoidal shape having a flat portion 28 at the apex. By forming the engagement protrusions 27 in this way, the flow of the material at the time of molding in the engagement protrusions 27 can be made smooth, the residual stress remaining in the engagement protrusions 27 after molding can be reduced, and repeated engagement release A product that is resistant to fatigue and has good stability over time can be provided. Further, by forming a locking surface 52 having an angle equivalent to the inclination angle after the elastic piece portion 26 is expanded on the rear end side of the elastic piece portion 26 of the plane portion 28, the relay member 29 is expanded when the elastic piece portion 26 is expanded. Since the outer peripheral side surface and the locking surface 52 are in contact with each other, the stress applied to the rear end of the engaging protrusion 27 that contacts and locks is dispersed throughout the locking surface 52, reducing the load caused by repeated use, and stability over time. Can provide good products.

  As a first modification of the second embodiment, as shown in FIG. 19, the outer diameter of the portion where the elastic piece portion 26 is formed is the same, and a series of curved surfaces that expand the inner diameter on the rear end side toward the rear end side. Thus, an example of a cylinder in which the cross-sectional thickness in the direction of the cylinder axis is changed between the rear end side and the front end side by making it slightly larger than the inner diameter on the front end side will be given. Not limited to this, a series of flat surfaces extending toward the rear end may be slightly larger than the inner diameter on the front end. Further, the inner diameter is the same, and the outer diameter on the rear end is reduced toward the rear end. It may be slightly smaller than the outer diameter on the front end side by a series of curved surfaces. In either case, the same effect can be obtained by forming a cylinder in which the cross-sectional thickness in the cylinder axis direction is changed between the rear end side and the front end side.

  In the locking tool 25 of the first modification in the second embodiment, the outer diameter of the portion where the elastic piece portion 26 is formed is the same, and a series of gradually expanding the inner diameter on the rear end side toward the rear end side. By making it slightly larger than the inner diameter on the front end side due to the curved surface, the cylinder thickness in the cylindrical axial direction has changed on the rear end side and the front end side, and from the rear end side of the cylinder so that the rear end can be expanded Two slits 43 having a length exceeding the thickness changing portion toward the front end side and having a constant width are provided at two opposite positions on the circumference, and elastic pieces 26 that can be expanded by the slits 43 are formed. On the inner surface near the rear end of the piece 26, an engaging projection 27 for engaging and connecting with the relay member 29 inserted into the cylinder is disposed.

  By forming the elastic piece portion 26 in this manner, the vicinity of the engagement protrusion 27 forming portion is more easily bent than in the vicinity of the expansion support portion 44, and the initial expansion of the elastic piece portion 26 is in the vicinity of the engagement protrusion 27 formation portion. Therefore, the load over which the engaging protrusion 27 gets over the step of the engaging groove 31 in the relay member 29 can be lowered more reliably, and the resistance when knocking is reduced, so that the feeling of knocking is improved. Further, as the expansion progresses, the vicinity of the expansion support portion 44 bends to improve the reaction force of the entire elastic piece portion 26, and the relay member 29 can be locked by the engagement protrusion 27, and a reliable core You can pay out. Further, the stress generated in the elastic piece portion 26 and the periphery thereof at the time of locking can be distributed from the vicinity of the expansion support portion 44 to the vicinity of the engagement protrusion 27 formation portion. Furthermore, by forming with a series of curved surfaces, the material flow at the time of molding can be improved, the residual stress can be reduced, and a product that is resistant to fatigue due to repeated disengagement and is stable over time can be provided. By forming a locking surface 52 having an angle equivalent to the inclination angle after the elastic piece portion 26 is expanded on the rear end side of the elastic piece portion 26 of the flat surface portion 28, the outer peripheral side surface of the relay member 29 when the elastic piece portion 26 is expanded. The stress applied to the rear end of the engaging protrusion 27 that contacts and locks is distributed over the entire locking surface 52, so that the load due to repeated use can be reduced, and a product with good temporal stability can be provided.

  As a comparative example, the locking tool 25 is provided with slits 43 at a constant width at two locations facing the circumference from the rear end side of the cylinder toward the front end side so that the rear end can be expanded. The elastic piece 26 that can be expanded by the slit 43 is formed with a constant thickness. On the inner surface of the elastic piece portion 26, an engagement protrusion 27 for engagement connection with a relay member 29 inserted into the cylinder is disposed.

  The elastic piece portion 26 formed in this way has no portion that is easily bent, and the engagement protrusion 27 is formed in the engagement groove 31 in the relay member 29 in order to expand the elastic piece portion 26 and release the engagement when knocked. Because the load over the level difference is applied at once, the knock is heavy and it feels strange.

DESCRIPTION OF SYMBOLS 1 Shaft cylinder 2 Tip ring 3 Tip spring 4 Slider 5 Tip member 6 Front shaft 7 Rear shaft 8 Shaft cylinder main body 9 Core feeding unit 10 Cushion spring 11 Reduced diameter part 12 Clip 13 Pipe 14 Core holding member 15 O ring 16 Chuck set 17 Ring 18 Tapered portion 19 Chuck body 20 Ball receiving seat 21 Hook portion 22 Ball 23 Chuck spring 24 Chuck stopper 25 Locking tool 26 Elastic piece portion 27 Engagement projection 28 Planar portion 29 Relay member 30 Large diameter portion 31 Engagement groove 32 Opening Part 33 Core insertion hole 34 Core guide pipe 35 Core tank 36 Core 37 Knock spring 38 Eraser receiving member 39 Eraser 40 Pressing member 41 Core engaging part 42 Core holding part 43 Slit 44 Expansion support part 45 First slit part 46 First Elastic piece 47 2nd Tsu DOO portion 48 the second elastic piece portion 49 the groove 50 the thick portion 51 thin portion 52 locking surface L writing lead

Claims (5)

In a mechanical pencil using a chuck body that allows advancement of the lead but prevents retraction of the lead, it is a cylinder and has at least two slits from the end of the cylinder toward the center so that the end can be expanded. An elastic piece portion that is provided at a location and can be expanded by the slit is formed, and an engagement groove portion of a member that presses the chuck body is engaged with a side surface of the member that presses the chuck body on the tip side of the elastic piece portion. Incorporates a locking tool formed with an engaging projection for stopping, and the slit has a wider width at the end than the slit bottom and / or the thickness of the elastic piece is at the end from the slit bottom A mechanical pencil characterized by a thinner side. The mechanical pencil according to claim 1, wherein the elastic piece portion is formed by changing the width of the slit and / or the thickness of the elastic piece in at least two stages. The mechanical pencil according to claim 1 or 2, wherein the elastic piece portion is formed by continuously changing the width of the slit and / or the thickness of the elastic piece portion. The engagement protrusion formed on the front end side of the elastic piece portion is formed to have a substantially trapezoidal shape having a flat portion at the apex, and the angle of the inclined surface of the trapezoidal shape is the rear end side compared to the front end side of the elastic piece portion The mechanical pencil according to claim 1, wherein the mechanical pencil is reduced. The engaging protrusion formed on the distal end side of the elastic piece portion is formed so as to have a substantially trapezoidal shape having a flat portion at the apex, and the elastic piece portion after the elastic piece portion is expanded on the elastic piece rear end side of the flat portion. The mechanical pencil according to any one of claims 1 to 3, wherein a locking surface having an angle equivalent to an inclination angle is formed.

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