JP5671913B2 - mechanical pencil - Google Patents

Description

The present invention relates to a chuck unit in which a chuck for preventing retraction of a lead is disposed in a shaft cylinder, and a mechanical pencil in which a sliding body for holding the lead is disposed in front of the chuck unit.
In particular, the lead of a certain length can be fed out by pressing the tip of the lead against a paper surface with a load (hereinafter referred to as pressing force) higher than the pressure during writing (hereinafter referred to as writing pressure), and then releasing it. The present invention relates to a mechanical pencil lead-out structure.

2. Description of the Related Art Conventionally, there has been known a mechanical pencil that performs a lead feeding operation by pressing a knock member disposed at a rear portion of a shaft tube in accordance with wear of the lead accompanying writing. However, in order to perform the feeding operation for aligning the core during writing, it is necessary to temporarily change the mechanical pencil, which causes troublesome operation.

  Therefore, in Patent Document 1, when the lead guide tube is retreated more than the retraction amount of the ball chuck mechanism when the tip of the lead is strongly pressed against the paper surface, and the pressing of the lead against the paper surface is eliminated, the core guide tube is A so-called tip knock mechanical pencil has been proposed in which the lead held by the lead detent member is advanced without being slipped and fed out.

Japanese Utility Model Publication No. 63-179178

The basic structure of the mechanical pencil disclosed in Patent Document 1 is such that a ring is fixed to the inner surface of a tip attached to the tip of the shaft cylinder, and an inclined posture and an upright posture in contact with the ring at the front portion of the ring An annular tilting member that can be removed is provided so as to be swingable, and is urged rearward by an interior spring and slidable in the axial direction at a front end surface portion away from the swinging fulcrum of the tilting member. And a rear end surface of the ring that is urged forward by a knock spring at a rear end surface portion close to the rotation fulcrum of the inclined moving member, and is brought into contact with the rear end edge portion of the core guide tube with the core detent member And a stopper front end surface provided at the front end of the outer cylinder of the ball chuck mechanism that can move between the step end surface formed on the inner surface of the shaft cylinder.
In this basic structure, when the tilting member swings and causes a lever action, the core guide tube has a length larger than the retraction amount of the chuck holding the core when the core is strongly pressed against the paper surface or the like. When the retracting force is removed and the pressing force is removed, the lead held by the lead detent member built in the lead guide tube is returned to the original position while being pulled out from the chuck, thereby enabling the lead to be fed forward.
Thus, it is very excellent in that the troublesomeness in operation of holding the mechanical pencil is eliminated by feeding the lead using the lever action. However, since each end of the tilting member is brought into contact with a different member to provide the action of the lever, the core guide tube and the stopper that are in contact with the tilting member are tilted with respect to the central axis of the shaft tube in the shaft tube. Will be placed. As a result, depending on the attitude of the mechanical pencil, when the core is pressed against the paper surface, the core guide tube, the stopper, and the member that moves back and forth integrally with these, specifically, the outer shaft of the ball chuck mechanism, etc. When sliding with the shaft cylinder, a frictional resistance exceeding the guide action is generated, and the operation may become unstable.

Therefore, in view of the above problems, the present invention provides a chuck unit in which a chuck for preventing retraction of a core is disposed in a shaft cylinder and a mechanical pencil in which a sliding body for holding the core is disposed in front of the chuck unit. An elastic member is disposed between the sliding member and the sliding member, and the chuck is urged rearward by the elastic member and holds the core, and the sliding member is moved forward by the elastic member. Energized, provided with a locking groove on the outer periphery of the sliding body , a plurality of locking portions engaging with the locking groove are provided in the shaft tube, and the engagement between the locking groove and the locking portion A pressing portion for releasing the chuck is provided in front of the chuck unit, and the elastic member is disposed inward of the pressing portion, and the tip of the core is strongly pressed against the paper surface, so that the chuck unit and the sliding body move backward. , Release the pressing force When the engagement groove and engagement said sliding body stays by with the locking portion, it is an summarized in that the chuck unit is moved forward while holding the core.

The present invention relates to a chuck unit in which a chuck for preventing retraction of a core is disposed in a shaft cylinder, and a mechanical pencil in which a sliding body for holding the core is disposed in front of the chuck unit, the chuck unit, the sliding body, An elastic member is disposed between the chuck member and the chuck member is urged backward by the elastic member and grips the core, and the sliding body is urged forward by the elastic member. A locking portion is provided on the outer periphery of the sliding body, a plurality of locking portions that engage with the locking groove are provided in the shaft cylinder, and a pressing portion that releases the engagement between the locking groove and the locking portion. Is provided in front of the chuck unit, the elastic member is disposed inward of the pressing portion, and the tip of the core is strongly pressed against the paper surface, so that the chuck unit and the sliding body are retracted, and the pressing force is reduced. When released, the locking groove and the front The sliding body stays due to the engagement with the locking portion, and the chuck unit is moved forward while holding the lead, so that the tip knocking can be performed without using the tilting member as the lever mechanism as shown in the prior art. Achieve the lead out of the core. For this reason, each member is disposed coaxially in the shaft tube and the tip member without being inclined with respect to the central axis of the shaft tube. As a result, the direction of the load applied at the time of knocking at the tip is shifted from the axial direction and transmitted to each member. Thus, the sliding resistance can be prevented from increasing, and the lead can be stably fed out regardless of the use posture of the mechanical pencil.

The longitudinal cross-sectional view which shows the structure of 1st Example of this invention. 1 is a partially enlarged longitudinal sectional view showing the configuration of a first embodiment of the present invention. The detailed perspective view of the sliding body and locking member of 1st Example of this invention. The operation | movement figure of 1st Example of this invention. The operation | movement figure of 1st Example of this invention. The operation | movement figure of 1st Example of this invention. The operation | movement figure of 1st Example of this invention. The partial expanded longitudinal cross-sectional view which shows the structure of 2nd Example of this invention. The detailed perspective view of the sliding body and locking member of 2nd Example of this invention. Operational diagram of the second embodiment of the present invention The partial expanded longitudinal cross-sectional view which shows the structure of 3rd Example of this invention. The AA sectional view of the 3rd example of the present invention. The operation | movement figure of 3rd Example of this invention.

The basic structure of a mechanical pencil having a lead-out structure according to the present invention is as follows. A chuck unit for preventing the retraction of the lead and a sliding body for holding the lead are disposed in the shaft tube, and a locking groove is provided on the outer periphery of the sliding member. Further, a plurality of locking portions that engage with the locking grooves are provided in the shaft cylinder, and a pressing portion that releases the engagement between the locking grooves and the engaging portions is provided in the chuck unit.
The operation will be described. When the core is pressed against the paper surface, the chuck unit and the sliding body move backward by the same distance, and when the pressing force is removed, the sliding body stays at the position where it is locked by the locking member. Since it advances, the length of the core which protrudes from a sliding body will increase. Thereafter, the pressing member attached to the chuck unit pushes the sliding body, so that the locking between the locking groove and the locking portion is released, and each member returns to the original position to complete the lead feeding. By adopting this structure, each member is arranged on the same axis without being inclined with respect to the central axis, and the lead-out operation is stably performed regardless of the gripping posture of the main body.

The mechanical pencil lead-out structure of the present invention will be described based on an embodiment. FIG. 1 is a longitudinal sectional view showing the configuration of the first embodiment of the present invention, and FIG. 2 is a partially enlarged longitudinal sectional view.
A front member 2 is fixed in front of the outer shaft cylinder 1. Inside the tip member 2, a locking member 3 is press-fitted and fixed, and a sliding body 4 is arranged to be movable back and forth. The sliding body 4 has a core holding member 5 press-fitted and fixed inside, and a core protection tube 6 fixed to the tip. A partial flanged cylinder 7 is disposed behind the sliding body 4, and an inclined cylinder 8 is press-fitted and fixed in front of the partial flanged cylinder 7. A push member 9 is fixed to the front portion of the inclined cylindrical body 8, and a chuck 10 is disposed inside the inclined cylindrical body 8. Further, a spherical ball 11 is disposed between the inner surface of the inclined cylindrical body 8 and a hemispherical concave portion 10a formed in front of the chuck 10 to constitute a chuck unit. Further, a resilient member 12 is disposed between a step portion 10b formed further forward than the concave portion 10a of the chuck 10 and a step portion 4a formed at the rear portion of the sliding body 4. The elastic member 12 urges the chuck 10 backward and the sliding body 4 is urged forward.
A cylinder 13 is arranged between the outer periphery of the partial flanged cylinder 7 and the outer shaft cylinder 1. A resilient member 14 is stretched between the front surface of the cylinder 13 and the rear end of the tip member 2 to urge the cylinder 13 rearward. In addition, a resilient member 15 is stretched between the inner step portion 13a of the cylindrical body 13 and the step portion 7a of the partially flanged cylinder 7, and urges the partial flanged cylinder 7 forward. doing.
Behind the chuck unit, a core tank unit comprising an inclined stepped cylinder 17 into which a core guide tube 16 is press-fitted forward, a core tank 18, an eraser 19, and a knock member 20 is slidable in the front-rear direction. Has been inserted. An inner flanged cylinder 21 is press-fitted inside the outer shaft cylinder 1, and a flange formed at the rear end of the inner flanged cylinder 21 and in the middle in the longitudinal direction of the core tank 18. A resilient member 22 is stretched between the portion 18a and the lead tank 18 is urged rearward. A small-diameter portion 1a is provided behind the outer shaft cylinder 1, and the clip 23 is fixed by press-fitting a cylindrical attachment portion 23a into the small-diameter portion 1a. The above is the configuration of the present embodiment, but the present embodiment is characterized by the operations of the sliding body 4, the locking member 3, and the pressing member 9.

Further, each member will be described in detail. The tip member 2 has a through hole 2a and step portions 2b, 2c, and 2d formed therein, an inner diameter portion 2e between the step portions 2b and 2c, and an inner diameter portion between the step portions 2c and 2d. Part 2f is formed. A screw 2g, an inner diameter enlarged diameter portion 2h, and a stepped portion 2i are formed behind the tip member 2, and the screw 2g is screwed and fixed to a screw 1b formed in front of the outer shaft cylinder 1.
A cylindrical portion 3a of the locking member 3 is press-fitted into the inner diameter enlarged portion 2h of the tip member 2 so as not to be detachable. As shown in FIG. 3, from the front end surface of the cylindrical portion 3a of the locking member 3, the arm portion 3b extends in a circular shape, and the arm portion 3b has a shape of a beam having an arc-shaped cross section. ing. At the tip of the arm portion 3b, a portion having an inner diameter smaller than the inner diameter of the cylindrical portion 3a is formed, forming a mountain-shaped key portion 3c.
A sliding body 4 is arranged in the tip member 2 and the locking member 3 so as to be movable back and forth. The sliding body 4 has a step portion 4a, a front side surface portion 4b, and a rear side surface portion 4c formed outside, and an inner step portion 4d and a through hole 4e formed inside. Further, a locking groove 4f is formed in a circumferential shape on the rear side surface portion 4c. In addition, since the outer diameter of the rear side surface portion 4c is slightly larger than the inner diameter of the key portion 3c of the locking member 3, the rear side surface portion 4c of the sliding body 4 is always attached to the key of the locking member 3 at normal times. The part 3c is touching, and the arm part 3 is bent and spreads. Further, when the sliding body 4 moves back and forth, a certain frictional force is generated. On the other hand, since the outer diameter of the locking groove 4 f of the sliding body 4 is sufficiently smaller than the inner diameter of the locking portion 3 c of the locking member 3, the locking portion 3 c of the locking member 3 is inserted into the locking groove 4 f of the sliding body 4. When fitted (locked state), the arm 3 is not bent. Further, in the locked state, the sliding body 4 is pressed and the locking is released by bringing the key portion 3c of the locking member 3 and the locking groove 4f of the sliding body 4 into engagement. It is necessary to give the sliding body 4 an unlocking load exceeding the locking force. This locking force is a force for the arm portion 3b to bend to the extent that the key portion 3c of the locking member 3 is removed from the locking groove 4f of the sliding body 4, so that the sliding body 4 slides back and forth during normal times. In this case, the frictional force generated between the sliding body 4 and the key portion 3c of the locking member 3 becomes larger. In this embodiment, the number of arm portions of the locking member is four, but it is possible to apply the frictional force and the locking force during the sliding to the cylindrical sliding body 4 evenly. In consideration of the above, the number of arm portions is not limited to four, and if it is three or more, the number of arm portions may be increased or decreased within a moldable range.
Any material can be used for the locking member 3 as long as it can maintain its shape, and metal or synthetic resin can be used. However, the arm portion 3b always receives an outward force from the central axis, and the sliding body. Since the operation of bending the arm portion 3b is repeated when releasing the lock of 4, the metal that is particularly difficult to be plastically deformed is desirable. The sliding body 4 is made of a synthetic resin or metal that is slidable and hard to wear because the key portion 3c of the locking member 3 contacts and slides on the rear side surface portion 4c. desirable. Examples include polyacetal and nylon. Incidentally, if this locking member is made into a rubber-like elastic body, it will react with oil contained in the core, etc., and the deterioration of the rubber-like elastic body over time will be promoted, and the function as an engaging member will be achieved. There is a risk that it will not run out. Further, in this example, the difference between the frictional force and the locking force is made easy by using a beam-like arm portion. In other words, if the engaging portion (the key portion 3c) is formed into an annular shape, it becomes difficult to obtain elastic deformation, and it becomes difficult to make a difference between the frictional force and the locking force. Further, when an annular member of a rubber-like elastic body is used, fixing to the tip member 2 depends on the frictional force between the rubber and the tip member 2, but the rubber-like elastic body is deformed when engaged with the sliding body. As a result, the possibility of falling off the tip member increases. On the other hand, the locking member of the present embodiment is fixed to the tip member 2 with the cylindrical portion 3a, and only the arm portion 3b is easily deformed in the outer diameter direction when engaged, so that it is dropped due to deformation of the fixed portion. Can be prevented.
The core holding member 5 press-fitted and fixed to the inner step portion 4d of the sliding body 4 has a through hole 5a in the axial direction, the front has a flat cone on the front, and the rear has a cylindrical shape. The material used for the member 5 may be an elastic resin, and specific examples thereof include nitrile butadiene rubber, silicone rubber, and fluorine rubber. Further, the core protection tube 6 press-fitted and fixed in the through hole 4e of the sliding body 4 is disposed for the purpose of protecting the fed core and improving the visibility, but may be formed integrally with the sliding body 4. . The material used for the core protection tube 6 is preferably a metal in order to protect the core (addition of a function for preventing core breakage). Specifically, iron and its alloy, copper and its alloy, etc. are mentioned.
Further, the front end of the elastic member 12 is in contact with the step portion 4a of the sliding body 4 to be slid, and is urged forward by the elastic force of the elastic member 12, and as a result, the sliding body 4 The tip is positioned by contacting the step 2b of the tip member 2. Further, the front side surface 4b of the sliding body 4 is formed to be slightly thinner than the inner diameter portion 2e of the tip member 2, and the rear side surface 4c is formed to be slightly thinner than the inner diameter portion 2f of the tip member 2. The moving body 4 becomes a guide when the inside of the tip member 2 slides back and forth.

As described above, the chuck unit is composed of the partial flanged cylinder 7, the inclined cylinder 8, the push member 9, the chuck 10, and the ball 11.
A small diameter portion 8a of the inclined cylindrical body 8 is detachably locked to the front inner surface of the partial flanged cylindrical body 7. On the inner surface of the inclined cylindrical body 8, an inclined surface 8 b that expands toward the front is formed. A chuck 10 is disposed inside the inclined cylindrical body 8 so as to be movable back and forth. A hemispherical concave portion 10a and a stepped portion 10b are formed on the front outer peripheral surface of the chuck 10, and a concave core gripping portion 10c for gripping the core is formed on the front inner surface. A spherical ball 11 is interposed between the concave portion 10 a and the inclined surface 8 b of the inclined cylindrical body 8.
Further, the rear end portion 9a of the pressing member 9 is press-fitted into the inner diameter enlarged portion 8c in front of the inclined cylindrical body 8 so as not to be detachable. In the embodiment, the pressing member 9 has a flange 9b formed in the middle of the entire length, and a small outer diameter portion 9c formed in front thereof. However, if the rear side of the push member 9 can be fixed to the inclined cylinder 8 so as not to be detachable and the front side is thinner than the inner diameter of the key part 3c of the locking member 3, it may take a different shape. Is possible. Furthermore, the inclined cylinder 8 and the pressing member 9 can be formed integrally.
Further, an elastic member 12 that urges the chuck 10 toward the rear is disposed inside the push member 9. The elastic member 12 urges the chuck 10 rearward so that the chuck 10 acts in a closing direction via the ball 11 that is in contact with the inclined surface 8b of the inclined cylindrical body 8, and grips the core 24. Yes. That is, a ball chuck mechanism that allows the lead to move forward but prevents its backward movement by a wedge action. In the present embodiment, the chuck 10 is configured by mutually opposing chuck pieces having the same shape divided into two.
A cylindrical body 13 is disposed inside the outer shaft 1 so as to be slidable back and forth. A resilient member 14 is stretched between the step 13b of the tubular body 13 and the step 2i of the tip member 2, and the tubular body 13 is urged rearward by the resilient force, and the rear end. The portion 13c is positioned by contacting the step portion 1c of the outer shaft cylinder 1. Inside the cylinder 13, the partial flanged cylinder 7 of the chuck set is slidably arranged back and forth, and between the step 7 a of the partial flanged cylinder 7 and the inner stage 13 a of the cylinder 13. Since the elastic member 15 is stretched, the partial flanged cylinder 7 is urged forward. Further, the cylindrical body 13 is formed with a window hole 13d, and the front end of the partial flanged cylinder 7 is brought into contact with the front end 13e of the window hole 13d so that the partial flanged cylinder 7 is positioned. ing. Further, a step portion 13 f is formed on the rear side of the inside of the cylindrical body 13, and a step portion 7 c is formed on the rear side of the partial flanged cylindrical body 7. By abutting against 7c of the flanged tubular body 7, excessive push-in of the tip knock during the tip knock operation is prevented.

The inclined cylindrical body 8 and the chuck 10 constituting the chuck unit are made of a metal having excellent strength and durability, for example, copper or an alloy thereof, iron or an alloy thereof, aluminum, or the like because the ball 11 is in contact with the recess 10a. Its alloys, zinc and its alloys are desirable, but relatively hard synthetic resins such as acrylonitrile, polycarbonate, polyacetal, etc., and those synthetic resins filled with inorganic powder, glass fiber, carbon fiber, etc. May be.

As described above, the core tank unit includes the core guide tube 16, the inclined stepped cylinder 17, the core tank 18, the eraser 19, and the knock member 20. An inclined step 17b is formed on the front side surface portion 17a of the inclined stepped cylindrical body 17 in a circumferential shape, and the inclined step 7d formed on the inclined stepped portion 17b and the rear inner diameter portion of the partial flanged cylindrical body 7 is formed. And the inclined stepped cylinder 17 is inserted into the partial cylinder 7.
Further, a core guide tube 16 is press-fit into the front of the inclined stepped cylinder 17 so as not to be detachable, and a core tank 18 is press-fit into the rear so as not to be detachable. A flange 18a is formed in the middle of the entire length of the core tank 18, and a window hole 18b is formed in front of the flange 18a and a protrusion 18c is formed in front of the window hole 18b. Further, a long window hole 18d is formed at a position facing the window hole 18b, and a claw portion 18e is formed inside the long window hole 18d.
Inside the outer shaft cylinder 1, an inner flanged cylinder 21 is press-fitted in a position facing the outer periphery of the window hole 18b and the long window hole 18d of the core tank 18. A resilient member 22 is stretched between the rear end of the inner flanged cylinder 21 and the flange 18d of the core tank 18 to urge the core tank 18 rearward. Since the inner flange 21a of the body 21 is in contact with the protrusion 18c and the claw portion 18c of the core tank 18, the core tank 18 does not come off rearward of the outer cylinder 1.
Further, an eraser 19 is detachably locked inside the rear enlarged diameter portion 18f of the core tank 18, and a knock member 20 covers the eraser 19 outside the rear enlarged diameter portion 18f. So as to be detachable.

Further, the urging force of each elastic member, the core holding force of the core holding member 5, the locking force brought about by the fitting of the key part 3c of the locking member 3 and the locking groove 4f of the sliding body 4, and the locking member The order of each of the frictional force generated between the key portion 3c and the rear side surface 4 of the sliding body 4 and the core gripping force of the ball chuck mechanism will be described in detail. The following magnitude relationship is required in order from the weakest.
The holding force of the ball chuck mechanism when the lead advances is weaker than the holding force of the lead holding member 5 and the urging force of the resilient member 12, and the urging force of the resilient member 12 acts on the locking groove 4 f of the sliding body 4. The latching force is weaker than the engagement force caused by the fitting, and the latching force is weaker than the urging force of the resilient member 15, and the urging force of the resilient member 15 is larger than the gripping force when the ball chuck mechanism is retracted. It is set weakly.
Further, the force obtained by adding the frictional force generated between the locking member key portion 3 c and the rear side surface portion 4 c of the sliding body 4 and the urging force of the elastic member 12 is weaker than the core holding force of the core holding member 5. The core holding force is set to be weaker than the sum of the locking force and the biasing force of the resilient member 12.
More specifically, in this embodiment, the gripping force when the lead of the ball chuck mechanism is advanced is 0.15 N or more and 0.20 N or less, and the core holding force of the core holding member 5 is 0.69 N or more, 0.0. 79N or less, the urging force of the resilient member 12 is 0.29 N or more and 0.39 N or less, and the locking force is 0.98 N or more and 1.47 N or less, and the resilient member 15 is attached. The force is configured to be 2.94 N or more and 3.33 N or less, the gripping force when the ball chuck mechanism is retracted is 7.84 N or more, and the friction force is 0.39 N or less.

Next, an operation (hereinafter referred to as a tip knocking operation) of pushing the lead strongly against the paper surface and feeding the lead in the first embodiment of the present invention will be described. 4 to 7 are operation diagrams of the tip knocking operation.

FIG. 4 shows a state during writing of the product of the present invention, and the core 24 protrudes from the tip of the core protection tube 6 by a length L. FIG.

In order to feed out the lead, the tip of the lead 24 protruding from the tip of the lead protection tube 6 is strongly pressed against the paper surface 25. The backward force (pressing force) applied to the core 24 at this time is larger than the force applied to the core 24 from the paper surface 25 during normal writing. This pressing force is transmitted from the core 24 to the chuck 10, and the chuck 10 tries to retreat, but the inclined surface 8 b on which the ball 11 interposed in the semicircular recess 10 a on the front outer peripheral surface of the chuck 10 abuts. The chuck 10 is firmly closed by the wedge action, and the lead 24 is firmly held so as not to be retracted (retraction of the lead 24 is prevented by the wedge action). Further, when the pressing force applied to the paper surface 25 by the user is increased and the pressing force exceeds the biasing force in front of the chuck unit of the elastic member 15, the elastic member 15 cannot resist and the chuck unit moves backward. By the retraction of the chuck unit, the core 24 gripped by the chuck 10 is also apparently retracted, and the core holding member 5 that grips the core 24 is also retracted. By this retreat, the sliding body 4 containing the core holding member 5 is also retracted.
Here, when the sliding body 4 moves backward until the locking groove 4f formed on the rear side surface portion 4c of the sliding body 4 coincides with the position of the key portion 3c of the locking member 3, the key portion 3c of the locking member 3 is moved. Is fitted into the locking groove 4f of the sliding body 4 so that the sliding body 4 is locked (see FIG. 5). At this time, the lead 24 is not extended. When further pressing force is applied from this state, the sliding body 4 does not move backward, and the core 24 slides backward on the core holding member 5, but the chuck unit holding the core 24 and the core 24 moves backward. The step 7c of the flanged cylinder 7 and the step 13f of the cylinder 13 are in contact with each other, so that the pressing operation is prevented from becoming excessive.

Next, when the operation of pressing the core 24 against the paper surface 25 is finished and the pressing force is released, the sliding body 4 remains in the state of being locked to the locking member 3 and does not move forward, so that the partial force is generated by the elastic force of the elastic member 15. The attached cylindrical body 7 is urged forward, and the entire chuck set advances until the tip 9d of the pressing member 9 comes into contact with the stepped portion 4a of the sliding body 4 (see FIG. 6). At this time, the chuck unit moves forward while holding the lead 24, but the lead holding force of the lead holding member 5 is set smaller than the sum of the locking force received by the sliding body 4 and the elastic force of the elastic member 12. Therefore, the lead 24 advances by sliding on the lead holding member 5. Therefore, the length of the core protruding from the tip of the core protection tube 6 is the length that the chuck unit has moved from the state shown in FIG. 5 to the state shown in FIG. 6, that is, the length indicated by L ′ in FIG. Just grow.

Even after the tip 9d of the pressing member 9 comes into contact with the stepped portion 4a of the sliding body 4, the chuck unit tries to advance further by the elastic force of the elastic member 15, and the elastic force is transmitted through the pressing member 9 to the sliding body. 4 is transmitted. Here, since the locking force of the sliding member 4 by the locking member 3 is set to be smaller than the elastic force of the resilient member 15, the sliding member 4 is pressed by the pushing member 9, and the locking groove 4f is engaged. The sliding member 4 comes off from the key portion 3c of the stop member 3 and returns to the original position as shown in FIG. The lead holding force of the lead holding member 5 is superior to the gripping force when the lead of the ball chuck mechanism is advanced. At this time, the lead 24 moves forward together with the sliding body 4 including the lead holding member 5, and the lead 24 is pulled out from the chuck. As a result, a series of operations for feeding the lead by the tip knock are completed.

Next, the feeding of the core stored in the core tank 18 will be described. When the knock member 20 attached to the rear of the core tank 18 is pressed (hereinafter referred to as a rear end knock), the partial flanged cylinder 7 is passed through the inclined step 17b of the inclined stepped cylinder 17 fixed integrally with the core tank 18. A pressing force is transmitted to the inclined step 7d. Further, since the partial flange 7b of the partial flanged cylinder 7 and the front end surface of the window hole 13d of the cylinder 13 are in contact with each other, the cylinder 13 also receives a force toward the front. When the pressing force exceeds the urging force of the resilient member 14 and the resilient member 15, the lead tank unit, the chuck unit, and the cylindrical body 13 move forward together. Here, when the front end of the flange portion 9b of the pressing member 9 attached to the front end of the chuck set comes into contact with the rear end of the locking member 3 fixed to the front member 2, the chuck unit and the cylinder 13 are moved. Be blocked. Further, when the pressing force to the knock member 20 is increased, the inclined step 7d of the partially flanged cylinder 7 gets over the inclined step 17b of the inclined stepped cylinder 17 and slides on the side surface portion 17a. Goes further. When the lead tank unit moves forward and the front end of the inclined stepped cylinder 17 contacts the rear end of the chuck 10, the elastic member 12 cannot resist and the chuck 10 moves forward. As the chuck 10 moves forward, gaps are formed between the recess 10a of the chuck 10 and the ball 11 and between the ball 11 and the inclined surface 8b of the inclined cylindrical body 8, and the wedge effect of the ball chuck mechanism does not work. The chuck 10 is expanded. At this time, if the mechanical pencil main body is held in a direction in which the tip member 2 is directed downward, the lead falls freely by gravity, passes through the lead guide tube 16 and the chuck 10, and the tip of the lead is the lead holding member. 5 to the rear of the through hole 5a. Here, when the pressing of the knocking member 20 is released, the chuck unit, the lead tank unit, and the cylindrical body 13 are moved backward together by the urging force of the resilient member 14 and the resilient member 22. It remains open, that is, the core does not retract. When the rear end portion 13c of the cylindrical body 13 comes into contact with the stepped portion 1c of the outer shaft cylinder 1 and the backward movement of the chuck unit and the cylindrical body 13 is prevented, only the lead tank unit is moved by the urging force of the elastic member 22. Retreating further, the inclined step 7 d of the partially ridged tubular body 7 is disengaged from the side surface portion 17 a of the inclined stepped tubular body 17. When the lead tank unit is retracted, the front end of the inclined stepped cylinder 17 is separated from the rear end of the chuck 10, the chuck unit again exhibits a wedge action, and the chuck 10 grips the lead. In this embodiment, the advancement of the chuck unit is regulated by the contact between the front end of the flange 9b of the push member 9 and the rear end of the locking member 3. For example, the push member is provided with a new step on the tip member 2. The advancing of the chuck unit may be prevented by abutment of other members, such as abutment with the flange portion 9b.
Even when the rear end knock is performed, the chuck unit, the lead tank unit, and the cylindrical body 13 move in the same manner. That is, the chuck 10 moves forward while holding the lead, and the lead is pushed into the through hole 5a against the frictional resistance (lead holding force) of the lead holding member 5 by the advance of the chuck body 10, and thereafter The chuck 10 is expanded. Then, the chuck 10 moves backward with the lead released, but the lead stays in place by the holding force of the lead holding member, and after the chuck 10 returns to its original position, the chuck 10 closes again and grips the lead. In this way, by repeating the rear end knock, the lead is drawn forward and protrudes from the lead protection tube 6 to enable writing.
Even if the tip of the lead does not protrude from the lead protection tube 6, if the lead is held by the lead holding member 5, the chuck unit and the sliding body 4 are pressed by pressing the lead protection tube 6 against the paper surface. By repeatedly performing a series of lead feeding operations such as retreating, locking the sliding member 4 and releasing the locked state of the sliding member 4 by the push member 9, the lead is drawn forward and writing becomes possible.

FIG. 8 is a longitudinal sectional view showing the configuration of the second embodiment of the present invention. A front member 102 is fixed in front of the outer shaft cylinder 101. Inside the tip member 102, the locking member 103 is press-fitted and fixed with the arm portion 103b extending rearward. Further, a sliding body 104 is disposed in the tip member 102 so as to be movable back and forth. A core holding member 105 is press-fitted and fixed inside the sliding body 104, and a core protection tube 106 is press-fitted and fixed to the tip. Yes. A partially tacked cylinder 107 is disposed behind the sliding body 104, and an inclined cylinder 108 is fixed in front of the partially tacked cylinder 107. A push member 109 is fixed to the front portion of the inclined cylindrical body 108. In addition, a chuck 110 is disposed inside the inclined cylinder 108, and a spherical ball 111 is interposed between the inner surface of the inclined cylinder 108 and a hemispherical recess 110 a formed in front of the chuck 110. It is arranged and constitutes a chuck unit. Further, a resilient member 112 is disposed between a step portion 110b formed further forward than the concave portion 110a of the chuck 110 and a step portion 104a formed at the rear portion of the sliding body 104, and the chuck 110 is disposed rearward. The sliding body 104 is urged forward. A cylindrical body 113 is disposed between the outer periphery of the partially flanged cylindrical body 107 and the outer shaft cylinder 101. A resilient member 114 is stretched between the front surface of the cylindrical body 113 and the rear end of the tip member 102 to urge the cylindrical body 113 backward. Further, a resilient member 115 is stretched between the inner step portion 113a of the cylindrical body 113 and the step portion 107a of the partially flanged cylinder 107, and urges the partially flanged cylinder 107 forward. ing. A core tank unit similar to the first embodiment is inserted behind the chuck unit so as to be slidable in the front-rear direction. The above is the configuration of the present embodiment. In the present embodiment, the point that the locking member 103 is press-fitted and fixed inside the tip member 102 with the arm portion 103b facing backward is the same as the first embodiment. Is different.

Further, each member will be described in detail.
The tip member 102 has a through hole 102a and step portions 102b, 102c, and 102d formed therein, an inner diameter portion 102e between the step portions 102b and 102c, and an inner diameter portion between the step portions 102c and 102d. A portion 102f is formed. A screw 102g, an inner diameter enlarged portion 102h, and a stepped portion 102i are formed at the rear of the tip member 102, and the screw 102g is screwed and fixed to a screw 101b formed in front of the outer shaft cylinder 101. Has been.
A cylindrical portion 103a of the locking member 103 is press-fitted into the stepped portion 102d of the tip member 102 so as not to be detachable. As shown in FIG. 9, the arm portion 103 b having a cross-sectional arc-shaped beam extends from the rear end surface of the cylindrical portion 103 a of the locking member 103, which is different from the first embodiment. is there. At the tip of the arm portion 103b, a portion having an inner diameter smaller than the inner diameter of the cylindrical portion 103a is formed to form a mountain-shaped key portion 103c. By adopting a structure in which the arm portion 103b extends from the rear end surface of the cylindrical portion 103a, even when the outer diameter of the cylindrical portion 103a is equal to the outer diameter of the arm portion 103b, the arm portion 103b is released when the locked state is released. A gap for bending outward can be secured without forming an undercut portion inside the tip member 102. This facilitates the formation (molding) of the locking member 103, and further reduces the stress concentration that occurs at the joint between the cylindrical portion 103a and the arm portion 103b of the locking member 103.
In addition, a sliding body 104 is disposed in the tip member 102 and the locking member 103 so as to be movable back and forth. The sliding body 104 has a stepped portion 104a, a front side surface portion 104b, and a rear side surface portion 104c formed outside, and an inner stepped portion 104d and a through hole 104e formed inside. Further, a locking groove 104f is formed in a circumferential shape on the rear side surface portion 104c, and further, a rear inclined portion 104g is formed on the rear side. The outer diameter of the locking groove 104 f of the sliding body 104 is sufficiently smaller than the inner diameter of the locking portion 103 c of the locking member 103, and the locking portion 103 c of the locking member 103 is fitted in the locking groove 104 f of the sliding body 104. At that time, the arm 103 does not bend. On the other hand, the outer diameter of the rear side surface portion 104c is slightly larger than the inner diameter of the key portion 103c of the locking member 103, but the inclination angle of the rear inclined portion 104g is gentler than the inclination angle of the locking groove 104f. . Therefore, when the sliding body 104 slides backward when the tip is knocked, the frictional force generated when the key portion 103c of the locking member 103 passes through the rear inclined portion 104g of the sliding body is slid with the key portion 103 of the locking member 103. This is smaller than the locking force caused by the engagement of the locking groove 104f of the moving body 104.
The front end of the resilient member 112 abuts on the step 104 a of the sliding body 104, the sliding body 104 is urged forward by the resilient force of the resilient member 112, and the tip is the step of the tip member 102. Positioning is performed by contacting 102b. Further, the front side surface 104b of the sliding body 104 is formed slightly narrower than the inner diameter portion 102e of the tip member 102, and the rear side surface 104c is formed slightly thinner than the inner diameter portion 102f of the tip member 102. It becomes a guide when the moving body 104 slides back and forth inside the tip member 102.
Incidentally, the position of the locking groove 104f of the sliding body 104 is provided in front of the position shown in FIG. 9, and the locking member 103 is always attached to the rear side surface portion 104c of the sliding body 104 at normal times as in the first embodiment. It is also possible to adopt a structure in which the key portion 103c touches and the arm portion 103 is bent and spreads, and a certain frictional force is generated when the sliding body 104 moves back and forth.

As described above, the chuck unit includes the partial flanged cylinder 107, the inclined cylinder 108, the push member 109, the chuck 110, and the ball 111.
An inclined cylindrical body 108 is fixed in a non-detachable manner in front of the partially tacked cylindrical body 107. A chuck 110 is disposed inside the inclined cylinder 108 so as to be movable back and forth. Between the inclined surface 108 b formed inside the inclined cylinder 108 and a hemispherical recess 110 a provided on the outer peripheral surface of the chuck 110. , A spherical ball 111 is interposed.
In addition, the push member 109 is fixed to the front of the inclined cylinder 108 so as not to be detachable. However, the inclined cylinder 108 and the push member 109 can be integrally formed. In addition, a resilient member 112 that urges the chuck 110 rearward is disposed inside the push member 109. The elastic member 112 urges the chuck 110 backward to cause the chuck 110 to act in the closing direction via the ball 111 in contact with the inclined surface 108b of the inclined cylindrical body 108, thereby gripping the core 124. Yes. That is, a ball chuck mechanism that allows the lead to move forward but prevents its backward movement by a wedge action. In the present embodiment, the chuck 110 is configured by mutually opposing chuck pieces having the same shape divided into two.
A cylindrical body 113 is disposed inside the outer shaft 101 so as to be slidable back and forth. A resilient member 114 is stretched between the step 113b of the tubular body 113 and the step 102i of the tip member 102, and the tubular body 113 is urged rearward by this resilient force, and the rear end. The portion 113 c is positioned by abutting against the step portion 101 c of the outer shaft cylinder 101. Inside the cylindrical body 113, the partial flanged cylinder body 107 of the chuck set is slidably arranged back and forth, and the stepped portion 107a of the partially flanged cylindrical body 107 and the inner stepped portion 113a of the cylindrical body 113 are arranged. Since the elastic member 115 is stretched between the two, the partial flanged cylinder 107 is urged forward. The cylindrical body 113 is formed with a window hole 113d, and the front end of the partial flange 107b of the partial flange 107 is brought into contact with the front end 113e thereof, whereby the partial flange 107 is positioned. Further, a step 113f is formed at the rear of the cylindrical body 113, and a step 107c is formed at the rear of the partially flanged cylinder 107. When the tip is knocked, the step 113f of the cylinder 113 and the partially flanged cylinder 107 are formed. No. 107c abuts to prevent excessive pushing of the tip knock.

Next, the tip knocking operation in the second embodiment of the present invention will be described. When the tip of the lead 124 protruding from the tip of the lead protection tube 106 is strongly pressed against the paper surface to feed out the lead, the chuck 110 is firmly closed by the wedge effect and the lead 124 is gripped. When the user further increases the pressing force, the elastic member 115 cannot resist and the chuck unit moves backward. By the retraction of the chuck unit, the core 124 gripped by the chuck 110 is also apparently retracted, and the core holding member 105 that grips the core 124 is also retracted. By this retreat, the sliding body 104 including the core holding member 105 also retreats. When the sliding body 104 moves backward until the locking groove 104f formed on the rear side surface portion 104c of the sliding body 104 matches the position of the key portion 103c of the locking member 103, the key portion 103c of the locking member 103 is moved. The sliding body 104 is locked in the locking groove 104f of the sliding body 104 (FIG. 10).
Next, when the operation of pressing the core 124 against the paper surface is finished and the pressing force is released, the sliding body 104 is not moved forward while being locked to the locking member 103, and is partially moved by the elastic force of the elastic member 115. The attached cylinder 107 is urged forward, and the entire chuck set advances until the tip 109d of the pushing member 109 contacts the step 104a of the sliding body 104. At this time, the chuck unit advances while holding the lead 124, and the lead holding force of the lead holding member 105 is smaller than the sum of the latching force received by the sliding body 104 and the resilient force of the resilient member 112, so Moves forward by sliding the lead holding member 105. For this reason, the length of the core protruding from the tip of the core protection tube 106 is extended by the length indicated by L ′ in FIG.
Here, even after the tip 109d of the pressing member 109 contacts the stepped portion 104a of the sliding body 104, the chuck unit tries to move forward by the elastic force of the elastic member 115, presses the sliding body 104 forward, and engages. The locking with the stop member 103 is released. Further, when the sliding body 104 is returned to the original position by the urging force of the elastic member 112, the core holding member 105 included in the sliding body 104 holds the core 124, so that the core 124 also moves forward to the chuck 110. A series of operations for extending the core by knocking the tip end is completed.

FIG. 11 is a longitudinal sectional view showing the configuration of the third embodiment of the present invention. A front member 202 is fixed in front of the outer shaft cylinder 201. Inside the tip member 202, the ball 226 is urged toward the inner side of the central axis by the resilient member 227. Further, a lid 228 is fixed to a side surface portion near the outer periphery of the tip member 202 so that the ball 226 and the elastic material 227 do not fall off from the tip member 202. Further, a sliding body 204 is disposed in the tip member 202 so as to be movable back and forth. A core holding member 105 is press-fitted and fixed inside the sliding body 204, and a core protection tube 206 is press-fitted and fixed at the tip. ing. A partial flanged cylinder 207 is disposed behind the sliding body 204, and an inclined cylinder 208 is fixed in front of the partial flanged cylinder 207. A push member 209 is fixed to the front portion of the inclined cylindrical body 208, and a chuck 210 is disposed inside. Further, a spherical ball 211 is disposed between the inner surface of the inclined cylindrical body 208 and a hemispherical recess 210a formed in front of the chuck 210, thereby constituting a chuck unit. Further, an elastic member 212 is disposed between a step portion 210b formed further forward than the concave portion 210a of the chuck 210 and a step portion 204a formed at the rear portion of the sliding body 204, and the chuck 210 is biased rearward. At the same time, the sliding body 204 is urged forward. A cylindrical body 213 is disposed between the outer periphery of the partially flanged cylindrical body 207 and the outer shaft cylinder 201. A resilient member 214 is stretched between the front surface of the cylinder 213 and the rear end of the tip member 202, and urges the cylinder 213 rearward. A resilient member 215 is stretched between the inner step portion 213a of the cylindrical body 213 and the step portion 207a of the partial flanged cylinder 207, and biases the partial flanged cylinder 207 forward.
Further, a core tank unit similar to that of the first embodiment is inserted into the rear of the chuck unit so as to be slidable in the front-rear direction. The above is the configuration of the present embodiment. In this embodiment, the ball 226 is disposed inside the tip member 202, and the resilient member 227 biases the ball 226 toward the inner side of the center axis of the tip member 202. This is different from the first and second embodiments.

Further, each member will be described in detail.
The tip member 202 has a through-hole 202a and step portions 202b, 202c, and 202d formed therein, an inner diameter portion 202e between the step portions 202b and 202c, and an inner diameter between the step portions 202c and 202d. A portion 202f is formed. A screw 202g, an inner diameter enlarged diameter portion 202h, and a stepped portion 202i are formed behind the tip member 202, and the screw 202g is screwed and fixed to a screw 201b formed in front of the outer shaft cylinder 201.
Further, the inner diameter portion 202f of the tip member 202 is provided with a hole 202j in the radial direction as shown in FIG. 12, and the ball 226 can rotate in the hole 202j and can slide in the radial direction of the cross section of the tip member 202. Placed in. In the hole 202j provided in the tip member 202, a hole reduced diameter portion 202k is formed at a position intersecting with the inner diameter portion 202f, and the inner diameter of the hole reduced diameter portion 202k is smaller than the ball diameter of the ball 226. It has become. In other words, the ball 226 does not fall off inward of the tip member 202 in the radial direction. Further, in order to prevent the ball 226 from falling off the outer side in the radial direction of the tip member 202, the lid 228 is fixed in a non-detachable manner, and the elastic member 227 is stretched between the lid 228 and the ball 226. .
A sliding body 204 is disposed in the tip member 202 so as to be movable back and forth. The sliding body 204 has a step portion 204a, a front side surface portion 204b, and a rear side surface portion 204c formed outside, and an inner step portion 204d and a through hole 204e formed inside. Further, a locking groove 204f is formed in the rear side surface portion 204c. Further, the front end of the resilient member 212 abuts on the stepped portion 204 a of the sliding member 204, and the sliding member 204 is biased forward by the resilient force of the resilient member 212. As a result, the sliding body 204 is positioned by the tip of the sliding body 204 coming into contact with the stepped portion 202b of the tip member 202. Further, the front side surface 204b of the sliding body 204 is formed to be slightly thinner than the inner diameter portion 202e of the tip member 202, and the rear side surface 204c is formed to be slightly thinner than the inner diameter portion 202f of the tip member 202. It becomes a guide when the moving body 204 slides back and forth inside the tip member 202.
Since the ball 226 is always pressed against the rear side surface portion 204c of the sliding body 204 by the resilient force of the resilient member 227, when the sliding body 204 slides back and forth, the ball 226, the sliding body 204, and the bullet A rolling friction force is generated between the generating members 227. Therefore, when the sliding body 204 is retracted when the tip is knocked and the locking groove 204f reaches the position of the ball 226, the ball 226 is urged radially inward by the resilient force of the resilient member 227. Is fitted into the locking groove 204f of the sliding body 204, and the sliding body 204 is locked. In order to release the sliding body 204 from the locked state, it is necessary to apply an unlocking load that exceeds the locking force provided by the resilient member 227 via the ball 226.
Since the locking force varies depending on the elastic force of the elastic member 227, the structure of the third embodiment can be used to easily adjust the locking force by replacing the elastic member 227. . In this embodiment, the coil-shaped elastic member is used, but instead of this, a rubber-like elastic body can be used for the purpose of generating a locking force. In this case, the locking force can be easily adjusted by changing the rubber hardness of the rubber-like elastic body. In this embodiment, the balls are arranged at three places. However, if it is possible to apply the rolling friction force and the locking force evenly to the cylindrical sliding body 204, the molding is performed. In addition, it is possible to increase the number of places where the balls are arranged within a possible range. Further, in order to reduce the rolling friction force generated between the ball 226 and the resilient member 227, a member (not shown) having a spherical recess may be disposed between the ball 226 and the resilient member 227. Is possible.
In addition, since the ball 226 comes into contact with and slides on the rear side surface portion 204c of the sliding body 204, it is desirable to use a synthetic resin or metal that has sliding properties and is not easily worn. Examples include polyacetal and nylon. In this embodiment, the cross-sectional shape of the locking groove 204f of the sliding body 204 is an arc shape. However, if the ball can be stably fitted, it can be a groove having a different cross-sectional shape such as a triangle.

As described above, the chuck unit includes the partially flanged cylinder 207, the inclined cylinder 208, the push member 209, the chuck 210, and the ball 211.
An inclined cylinder 208 is fixed to the front of the partially tacked cylinder 207 so as not to be detached. A chuck 210 is disposed inside the inclined cylinder 208 so as to be movable back and forth. Between the inclined surface 208b formed inside the inclined cylinder 208 and a hemispherical recess 210a provided on the outer peripheral surface of the chuck 210. Has a ball 211 interposed.
The push member 209 is fixed to the front of the inclined cylinder 208 so as not to be detachable. However, the inclined cylinder 208 and the push member 209 can be integrally formed. Further, an elastic member 212 that urges the chuck 210 rearward is disposed inside the push member 209. The elastic member 212 urges the chuck 210 backward to cause the chuck 210 to act in the closing direction via the ball 211 in contact with the inclined surface 208 b of the inclined cylindrical body 208, thereby gripping the core 224. Yes. That is, a ball chuck mechanism that allows the lead to move forward but prevents its backward movement by a wedge action. In the present embodiment, the chuck 210 is configured by mutually opposing chuck pieces having the same shape divided into two.
Inside the outer shaft 201, a cylinder 213 is slidably arranged. An elastic member 214 is stretched between the step 213b of the cylinder 213 and the step 202i of the tip member 202, the cylinder 213 is urged rearward, and the rear end 213c is the outer shaft cylinder. Positioning is performed by contacting the stepped portion 201c of 201. Inside the cylindrical body 213, the partial flanged cylinder 207 of the chuck set is slidably arranged back and forth, and the stepped portion 207a of the partially flanged cylindrical body 207 and the inner stepped portion 213a of the cylindrical body 213 are arranged. Since the elastic member 215 is stretched between the two, the partial flanged cylinder 207 is urged forward. The cylindrical body 213 is formed with a window hole 213d, and the front end of the partial flange 207b of the partial flanged cylinder 207 contacts the front end 213e, whereby the partial flanged cylinder 207 is positioned. Further, a step portion 213f is formed at the rear side of the cylindrical body 213, and a step portion 207c is formed at the rear side of the partially flanged cylindrical body 207. 207c is in contact with each other, so that excessive pushing of the tip knock is prevented.

Next, the tip knocking operation in the third embodiment of the present invention will be described. When the tip of the lead 224 protruding from the tip of the lead protection tube 206 is strongly pressed against the paper surface to feed the lead, the chuck 210 is firmly closed by the wedge effect, and the lead 224 is gripped. When the user further increases the pressing force, the elastic member 215 cannot resist and the chuck unit moves backward. By the retraction of the chuck unit, the core 224 gripped by the chuck 210 is also apparently retracted, and the core holding member 205 that grips the core 224 is also retracted. Due to this retreat, the sliding body 204 containing the core holding member 205 is also retracted. Then, when the sliding body 204 moves backward until the locking groove 204f formed in the rear side surface portion 204c of the sliding body 204 matches the position of the ball 226 attached to the tip member 202, the ball 226 is moved by the resilient member 227. Since the tip member 202 is biased toward the inner side in the radial direction, the ball 226 fits into the locking groove 204f of the sliding body 204, and the sliding body is locked (FIG. 13).
Next, when the operation of pressing the core 224 against the paper surface is finished and the pressing force is released, the sliding body 204 is engaged with the ball 226 biased by the elastic force of the elastic member 227 and does not advance. The partial flanged cylinder 207 is urged forward by the elastic force of the member 215, and the entire chuck set advances until the tip 209d of the pushing member 209 contacts the stepped portion 204a of the sliding body 204. At this time, the chuck unit moves forward while holding the lead 224, but the lead holding force of the lead holding member 205 is smaller than the sum of the latching force received by the sliding body 204 and the elastic force of the elastic member 212. 224 advances by sliding on the core holding member 205. For this reason, the length of the core protruding from the tip of the core protection tube 206 is extended by the length indicated by L ′ in FIG.
In addition, even after the tip 209 d of the pressing member 209 contacts the stepped portion 204 a of the sliding body 204, the chuck unit tries to move forward by the elastic force of the elastic member 215, and the elastic force is slid through the pressing member 209. It is transmitted to the moving body 204. Here, since the locking force that the ball 226 biased by the resilient member 227 brings to the sliding body 204 is set to be smaller than the resilient force of the resilient member 215, the sliding body 204 is pushed by the pressing member 209. The locking groove 204f is released from being locked by the ball 226, and the sliding member 204 returns to the original position by the urging force of the elastic member 212. At this time, since the lead holding member 205 included in the sliding body 204 holds the lead 224, the lead 224 is also moved forward and pulled out from the chuck 210, and a series of operations of feeding the lead by the tip knock is completed.

DESCRIPTION OF SYMBOLS 1 Outer cylinder 2 Tip member 3 Locking member 4 Sliding body 5 Core holding member 6 Core protection tube 7 Partially-barbed cylinder 8 Inclined cylinder 9 Pushing member 10 Chuck 11 Ball 12 Elastic member 13 Cylindrical body 14 Elastic member 15 Elastic member 16 Core guide tube 17 Inclined stepped cylinder 18 Core tank 19 Eraser 20 Knock member 21 Inner flange member 22 Elastic member 23 Clip 24 Core 25 Paper surface 226 Ball 227 Elastic member 228 Lid

Claims (3)

In a mechanical pencil in which a chuck unit in which a chuck for preventing retraction of the core is disposed in the shaft cylinder and a sliding body for holding the core in front of the chuck unit is disposed, an elastic force is provided between the chuck unit and the sliding body. A repellent member is arranged, and the chuck is urged rearward by the elastic member and grips the core, and the sliding body is urged forward by the elastic member, and an outer periphery of the sliding body Provided with a locking groove on the top, a plurality of locking portions engaging with the locking groove are provided in the shaft cylinder, and a pressing portion for releasing the engagement between the locking groove and the locking portion is provided on the chuck unit. Is provided in front of the pressing portion, the elastic member is disposed inside the pressing portion, and the tip of the core is strongly pressed against the paper surface so that the chuck unit and the sliding body are retracted, and the pressing force is released, A locking groove and the locking portion; Said sliding body stays the engagement, the mechanical pencil to advance in a state in which the chuck unit holds the core. The mechanical pencil according to claim 1, wherein the locking portion is formed in the vicinity of a tip of an arm portion extending in a beam shape, and a cross-sectional shape in a longitudinal direction of the locking portion is a substantially triangular shape. The mechanical pencil according to claim 1, wherein the locking portion is a sphere biased by a resilient member.

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