Rod-shaped body feeding mechanism

Abstract

In conventional mechanical pencils, the gap between the chuck and the cylindrical body located outside the chuck becomes partially larger, which tends to partially widen the radial range of motion of the chuck. This can lead to a radial misalignment between the central axis of the rod-shaped body gripped by the chuck and the central axis of the stopper that extends from the cylindrical body through various components. If the rod-shaped body is advanced while misaligned, its feeding will be hindered, and such a chuck shape may worsen the rod-shaped body's feeding performance. The present invention aims to provide a rod-shaped body feeding mechanism that is easy to assemble and does not easily worsen the rod-shaped body's feeding performance. [Solution] The rod-shaped body feeding mechanism according to the present invention is characterized in that a groove is formed on the surface perpendicular to the central axis of the hole inside the chuck, the groove opening radially outward, and the groove is recessed at least in the axial direction.

Description

Technical Field

[0001] The present invention relates to an unwinding mechanism for a rod-shaped body.

Background Art

[0002] Conventionally, an unwinding mechanism for a rod-shaped body, such as a chuck set built into a mechanical pencil, has been disclosed. As a mechanical pencil, there has been disclosed one that can unwind the core by repeating the gripping or releasing of the core by a chuck capable of changing the gripping force according to an operation. For example, Patent Document 1 discloses an invention related to a mechanical pencil having a mechanism in which chuck pieces open and close as the chuck moves back and forth, and the core, which is a rod-shaped body, is gripped or pulled forward. The chuck of the invention consisted of two half parts and had a shape in which a part of a cylinder was cut out in the radial direction of the two half parts. When the chuck has a shape in which a part of a cylinder is cut out, it is possible to determine the circumferential direction with respect to the assembly jig used during assembly, so that the assembly property is good in an assembly process in which other parts need to be arranged in an arbitrary direction.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in mechanical pencils using such a chuck set, the gap between the chuck and the cylindrical body located outside the chuck becomes partially larger, making it easier for the radial range of motion of the chuck to partially widen. This could potentially cause a radial misalignment between the central axis of the rod-shaped object gripped by the chuck and the central axis of the stopper, which is connected to the cylindrical body and various components. The stopper is a component that elastically deforms when a rod-shaped object is inserted and is capable of gripping the rod-shaped object by its elasticity. However, if the central axes of the chuck and the stopper are misaligned when attempting to feed out the rod-shaped object, insertion of the rod-shaped object into the stopper will not be successful, and as a result, the feeding of the rod-shaped object will be hindered. Therefore, such a chuck shape could worsen the feeding performance of the rod-shaped object.

[0005] Considering the circumstances described above, the present invention aims to provide a rod-shaped body dispensing mechanism that is easy to assemble and does not easily impair the dispensing performance of the rod-shaped body. [Means for solving the problem]

[0006] The rod-shaped body feeding mechanism according to the present invention comprises at least a cylindrical body, a chuck, and a spring. The cylindrical body is positioned radially outside the chuck, and the chuck has a hole that penetrates from the front end to the rear end on its inside, with the front part divided into at least two or more sections. Inside the front section of the divided section, there is a gripping section that has the function of gripping and releasing the core body, and is positioned to move back and forth relative to the cylindrical body. The spring biases the chuck backward, and a groove is formed on the surface perpendicular to the central axis of the hole inside the chuck, opening radially outward. The groove is recessed at least in the axial direction, and the number of grooves is equal to or greater than the number of sections in front of the chuck. [Effects of the Invention]

[0007] The rod-shaped body feeding mechanism according to the present invention allows for orientation relative to the assembly jig using grooves formed in the chuck, resulting in good assembly efficiency. Even with a cutting depth equivalent to that of a conventional cylindrical shape with a portion cut off, the gap between the cylindrical body and the chuck can be made relatively small, and the radial range of motion of the chuck can be narrowed. This reduces the radial misalignment between the central axis of the rod-shaped body gripped by the chuck and the central axis of the stopper via the cylindrical body and each component, thus not hindering the feeding of the rod-shaped body when feeding it out and making it less likely to worsen the rod-shaped body feeding performance. [Brief explanation of the drawing]

[0008] [Figure 1] External view of mechanical pencil 1 in a writing-ready state. [Figure 2] Longitudinal section along the axial direction in Figure 1 [Figure 3] Enlarged view of part A (end member 20) in Figure 2 [Figure 4] Enlarged view of section B (chuck set 30) in Figure 3. [Figure 5] External perspective view of Chuck 31 [Figure 6] Figure 5 shows a longitudinal cross-sectional view of the chuck 31 along its axial direction. [Figure 7] A longitudinal cross-sectional view rotated 90° around the axis from Figure 6. [Figure 8] Rear view showing the groove-forming surface 31d1 of the chuck 31 in Figure 5. [Figure 9] Enlarged view of section C (groove 31d) in Figure 6 of Example 1 [Figure 10] Enlarged view of section C (groove 31d) in Figure 6 of Example 2 [Figure 11] Enlarged view of section C (groove 31d) in Figure 6 of Example 3. [Figure 12] Enlarged view of section C (groove 31d) in Figure 6 of Example 4 [Figure 13] Rear view showing the groove-forming surface 31d1 of the chuck 31 in Figure 5 of Example 5. [Figure 14] Rear view showing the groove-forming surface 31d1 of the chuck 31 in Figure 5 of Example 6 [Figure 15]Back view showing the groove forming surface 31d1 of the chuck 31 in FIG. 5 of Example 7 [Figure 16] Back view showing the groove forming surface 31d1 of the chuck 31 in FIG. 5 of Example 8 [Figure 17] Back view showing the groove forming surface 31d1 of the chuck 31 in FIG. 5 of Example 9 [Figure 18] Back view showing the groove forming surface 31d1 of the chuck 31 in FIG. 5 of Example 10 [Figure 19] Back view showing the groove forming surface 31d1 of the chuck 31 in FIG. 5 of Example 11 [Figure 20] Back view showing the groove forming surface 31d1 of the chuck 31 in FIG. 5 of Example 12 [Figure 21] Partial enlarged view of part C (groove part 31d) in FIG. 6 of Example 13 [Figure 22] Partial enlarged view of part C (groove part 31d) in FIG. 6 of Example 14 [Figure 23] Partial enlarged view of part C (groove part 31d) in FIG. 6 of Example 15 [Figure 24] Partial enlarged view of part C (groove part 31d) in FIG. 6 of Example 16 [Figure 25] Partial enlarged view of part C (groove part 31d) in FIG. 6 of Example 17 [Figure 26] Partial enlarged view of part C (groove part 31d) in FIG. 6 of Example 18 [Figure 27] Partial enlarged view of part C (groove part 31d) in FIG. 6 of Example 19 [Figure 28] Partial enlarged view of part C (groove part 31d) in FIG. 6 of Example 19 [Figure 29] Partial enlarged view of part C (groove part 31d) in FIG. 6 of Example 20 [Figure 30] Back view showing the groove forming surface 31d1 of the chuck 31 in FIG. 5 of Example 21 [Figure 31] Back view showing the groove forming surface 31d1 of the chuck 31 in FIG. 5 of Example 22 [Figure 32] Back view showing the groove forming surface 31d1 of the chuck 31 in FIG. 5 of Example 23 [Figure 33] Back view showing the groove forming surface 31d1 of the chuck 31 in FIG. 5 of Example 24 [Figure 34]Rear view showing the groove-forming surface 31d1 of the chuck 31 in Figure 5 of Example 25 [Figure 35] Rear view showing the groove-forming surface 31d1 of the chuck 31 in Figure 5 of Example 26 [Figure 36] Rear view showing the groove-forming surface 31d1 of the chuck 31 in Figure 5 of Example 27 [Modes for carrying out the invention]

[0009] Hereinafter, a mechanical pencil equipped with a chuck set as a rod-shaped body extension mechanism according to the present invention will be described with reference to the attached drawings. Note that the mechanical pencil is just one example, and it may also be a retractable eraser, art supplies, cosmetics, etc., equipped with a rod-shaped body extension mechanism. However, the dimensions, materials, shapes, relative positions, etc. of the components described as embodiments or shown in the drawings are not particularly limited unless otherwise specified in this specification.

[0010] In this specification, "central axis" or "axis" means the axis that runs through the longitudinal center of the mechanical pencil 1. "Front" or "forward" means the side of the tip member 20 as seen from the barrel 10, and conversely, "rear" or "backward" means the side opposite to the tip member 20 as seen from the barrel 10. "End" or "end" means the part of the shape element of each member that is located at the end along the axial direction. "Radial direction" means the radial direction when a circle is assumed to have the central axis as its center point as seen from each member, and "circumferential direction" means the circumferential direction when a circle is assumed to have the central axis as its center point as seen from each member. "Outer side" means the radially outer side with respect to the central axis as seen from each member, and conversely, "inner side" means the radially inner side with respect to the central axis as seen from each member. "Outer surface" means the surface of the shape element of each member that is exposed radially outward with respect to the central axis as a reference, and conversely, "inner surface" means the surface of the shape element of each member that is exposed radially inward with respect to the central axis as a reference.

[0011] First, an embodiment of the mechanical pencil 1 of the present invention will be described with reference to Figures 1 to 4.

[0012] Figure 1 shows the external appearance of a mechanical pencil 1 in a writing state according to one embodiment of the present invention. Figure 2 is a longitudinal cross-sectional view along the axial direction showing one cross-section of the mechanical pencil 1 shown in Figure 1. Figure 3 is a partially enlarged view showing part A, the tip member 20 portion, of the mechanical pencil 1 in Figure 2. Figure 4 is a partially enlarged view showing part B, the chuck set 30 portion, of the mechanical pencil 1 in Figure 3.

[0013] In one embodiment of the present invention, the mechanical pencil 1, as shown in Figures 1 and 2, comprises at least a barrel 10, a tip member 20 positioned at the front end of the barrel 10, a chuck set 30 positioned inside the barrel 10, and an operating body 40 capable of pressing the chuck set 30 from the rear end. The mechanical pencil 1 also requires at least one lead 70 inserted through the inside of the barrel when writing. The lead 70 has an extruded shape with a substantially circular cross-section. As the lead 70 wears down, the wear particles become the writing line. The lead 70 is made of a material that contains at least graphite. The lead 70 can be housed inside the lead tank 46, which will be described later.

[0014] The barrel 10 is positioned along the axial direction of the mechanical pencil 1. The barrel 10 is composed of one or more parts. In this embodiment, as shown in Figure 2, the barrel 10 is composed of a front barrel 11 and a rear barrel 12. The front barrel 11 and the rear barrel 12 are formed and joined by so-called integral molding. The front barrel 11 is made of resin containing metal powder, while the rear barrel 12, unlike the front barrel 11, is made of resin that does not contain metal powder. A clip 60 is fixed and positioned on the rear outer side of the rear barrel 12 by fitting. The clip 60 is made of iron. Note that this embodiment is just an example, and the barrel 10 may be a single part rather than integrally molded from two parts, or conversely, it may be formed and joined by integral molding from three or more parts. For example, a grip may be provided on the holding part. The barrel 10 may be made of resin that does not contain metal powder, or it may be made of metal. The clip 60 may be integrally formed with the barrel 10, or it may not be positioned. Clip 60 may be made of a metal other than iron, or it may be made of resin.

[0015] The tip member 20 is positioned in front of the shaft cylinder 10. The tip member 20 is composed of one or more parts. In this embodiment, as shown in Figure 3, the tip member 20 is composed of a tip 21, a tip pipe 22, a slider 23, a return stopper 28, a return stopper retainer 27, a tip ring 26, a tip spring 25, and an O-ring 24. The tip 21 is connected to the shaft cylinder 10 by screwing. The tip 21 is made of brass. The tip pipe 22 can extend and retract from the front end of the tip 21. The tip pipe 22 is connected to the inside of the slider 23 by press-fitting. The tip pipe 22 is made of stainless steel. The slider 23 is located inside the tip 21 and can move back and forth in the axial direction. The slider 23 is made of brass. The return stopper 28 has an inner diameter smaller than the outer diameter of the core 70 but is elastically deformable. When elastic deformation occurs, it generates an elastic force that tries to return the core to its original shape, causing the inner diameter to shrink in the direction of the central axis. Therefore, when the core 70 is inserted through the stopper 28, the core 70 can be held in place by the inner circumferential surface. If the core 70 is moved back and forth in this state, a frictional force is generated between the stopper 28 and the core 70, creating resistance to the back-and-forth movement. The stopper 28 is press-fitted into the inside of the slider 23 on its outer circumferential surface. The stopper 28 is made of rubber. The stopper retainer 27 is positioned to prevent the stopper 28 from coming out of the slider 23. The stopper retainer 27 is press-fitted into the slider 23. The stopper retainer 28 is made of brass. The tip ring 26 is positioned to fix the slider 23 inside the tip 21. The tip ring 26 is press-fitted into the inside of the tip 21. The tip ring 26 is made of brass. The tip spring 25 is positioned to bias the slider 23 forward. The tip spring 25 is positioned between the slider 23 and the tip ring 26. The tip spring 25 is made of stainless steel. The O-ring 24 is positioned to lock the slider 23 to the tip ring 26 when the tip pipe 22 is retracted. The O-ring 24 is mounted on the outside of the slider 23. The O-ring 24 is made of rubber. Note that this embodiment is just one example, and the materials used for each component may differ from those described above.For example, the tip 21, slider 23, stopper 27, and tip ring 26 may be made of a metal other than brass, or they may be made of resin. The tip pipe 22 and tip spring 25 may be made of a metal other than stainless steel, or they may be made of resin. The stopper 28 and O-ring 24 may be made of an elastically deformable material or have a cantilevered shape instead of rubber. The tip member 20 does not need to have any other parts except for the tip 21. For example, the tip pipe 22 may not be provided, and instead the lead 70 may be exposed directly from the slider 23 or the front end of the tip 21 to allow writing. The stopper 28 may not be provided, and instead the slider 23 or tip 21 may be configured to hold the lead 70 on its inner surface. The tip 21 may be connected to the barrel 10 by fitting, press-fitting, or other means other than screwing. The tip spring 25 does not have to be a spring as long as it is made of an elastically deformable material. For example, it may be made of a material such as sponge or gel. Alternatively, instead of using the O-ring 24, a convex shape can be provided on the outer surface of the slider 23 and fitted onto the inner surface of the tip ring 26 to serve as a substitute for locking.

[0016] The chuck set 30 is positioned in the internal space formed by the connection between the shaft cylinder 10 and the end member 20. The chuck set 30 is composed of one or more parts. In this embodiment, as shown in Figure 4, the chuck set 20 consists of a chuck 31, a cylindrical body 32, a ball 33, a chuck spring 34, and a chuck stopper 35. The chuck 31 has a hole 31c that penetrates from the front end to the rear end on its inside, and is divided into at least two or more sections at the front, while the rear remains connected. The inner circumferential surface 31c5 of the front divided section 31a of the chuck 31 is provided with a gripping section 31c1 that has the function of gripping or releasing the core 70. The chuck 31 is positioned to move back and forth relative to the cylindrical body 32. The chuck 31 is made of brass. The cylindrical body 32 can grip and release the core 70 by applying external force to the chuck 31 directly or indirectly via the ball 33. The cylindrical body 32 is positioned on the outside of the chuck 31. The cylindrical body 32 is made of brass. The ball 33 is positioned between a recess 31a2 provided on the outer circumferential surface of the gripping portion 31c1 of the chuck 31 and a tapered shape on the inner circumferential surface 31c5 of the cylindrical body 32 that decreases in diameter from front to rear. The ball 33 is made of carbon steel. The chuck spring 34 is positioned to bias the chuck 31 backward. The chuck spring 34 is positioned between the cylindrical body 32 and the chuck 31. The chuck spring 34 is made of stainless steel. The chuck stopper 35 is positioned to prevent the ball 33 from coming out of the chuck 31 or the cylindrical body 32. The chuck stopper 35 is crimped and fixed to the cylindrical body 32. The chuck stopper 35 is made of brass. Note that this embodiment is just one example, and each component may be made of a different material than those described above. The chuck 31, the cylindrical body 32, and the chuck stopper 35 may be made of a metal other than brass, or they may be made of resin. The ball 33 may be made of a metal other than carbon steel, or they may be made of resin. The chuck spring 34 may be made of a metal other than stainless steel, or they may be made of resin. The chuck set 30 may not have the ball 33, and the chuck 31 and the cylindrical body 32 may be in direct contact.

[0017] The operation of the chuck set 30 configured in this way will now be explained. In the assembled state, the elastic force of the chuck spring 34 constantly biases the chuck 31 backward relative to the cylindrical body 32. As a result, the divided portion 31a of the chuck 31 receives an external force from the tapered shape of the cylindrical body 32 via the ball 33. Because the tapered shape of the cylindrical body 32 is tapered from front to back, the more the chuck 31 tries to move backward due to the biasing force of the chuck spring 34, the stronger the radial external force applied to the chuck 31 via the ball 33. This conversion of force in the front-to-back direction into force in the radial direction by the tapered shape is called the "wedge effect," and this effect is frequently used in the chucks of mechanical pencils. This radial external force exerts a gripping force on the lead 70 passing through the center of the chuck 31. Therefore, when the lead 70 is inserted through the chuck 31, the chuck 31 is always gripping the lead 70. Next, the operation when a force is applied that tries to move the lead 70 backward will be explained. Since the chuck 31 grips the core 70, the chuck 31 and the core 70 try to move together. Then, due to the wedge effect, the chuck 31 is subjected to an even stronger radial external force from the cylindrical body 32. As a result, the chuck 31 grips the core 70 more tightly. The frictional force generated by this is very large, so the core 70 does not move. In other words, as a result, the movement of the core 70 backward relative to the chuck 31 is prevented. On the other hand, let's explain the operation when a force acts to move the core 70 forward. Here again, since the chuck 31 grips the core 70, the chuck 31 and the core 70 try to move together. However, due to the wedge effect, the external force applied to the chuck 31 from the cylindrical body 32 becomes smaller, the opposite to when it is moving backward. In addition, the chuck 31 is subjected to an external force from the cylindrical body 32 via the ball 33. In general, the rolling friction force generated by the contact between a sphere like the ball 33 and a surface is far smaller than the static friction force generated by the contact between surfaces. Therefore, the external force applied to the chuck 31 via the ball 33 becomes smaller and smaller. As the applied external force decreases, the chuck 31 ceases to grip the core 70.Therefore, the only resistance between the chuck 31 and the core 70 is the static friction force between the gripping portion 31c1 of the chuck 31 and the outer surface of the core 70. If the force moving forward is greater than this static friction force, the core 70 will move forward as if being pulled out of the chuck 31. In reality, this static friction force is very small, and the core 70 can easily move forward. In other words, as a result, the core 70 is allowed to move forward relative to the chuck 31.

[0018] The operating body 40 is positioned in the internal space formed by the connection between the shaft cylinder 10 and the tip member 20, or exposed from the rear end of the shaft cylinder 10. The operating body 40 is positioned behind the chuck set 30. The operating body 40 is positioned so that the cylinder 32 or the chuck 31 can be advanced by pressing the rear end. The operating body 40 is composed of one or more parts. As shown in Figure 2, in this embodiment, the operating body 40 is composed of a locking device 48, a relay member 47, a core 49, a lead tank 46, a knock spring 50, a cushion spring 51, an eraser holder 43, an eraser 44, an eraser stopper plate 45, a knock 42, and a knock cover 41. The locking device 48 is positioned in contact with the rear end of the cylinder 32 of the chuck set 30. The locking device 48 is made of resin. The relay member 47 is fixed inside the locking device 48 by fitting. The relay member 47 is made of resin. The core 49 is positioned outside the chuck set 30, locking device 48, and intermediate member 47. The core 49 is in contact with the locking device 48. The core 49 is positioned to contact the rear end of the tip metal 21 of the tip member 20. The core 49 is made of resin. The core tank 46 is press-fitted to the rear outside of the intermediate member 47. The core tank 46 is capable of housing the core 70 inside. The core tank 46 is made of resin. The knock spring 50 is positioned to bias the chuck set 30, locking device 48, intermediate member 47, and core tank 46 backward. The knock spring 50 is positioned between the core 49 and the core tank 46. The knock spring 50 is made of iron. The cushion spring 51 is positioned to bias the core 49 forward. The cushion spring 51 is positioned between the core 49 and the shaft cylinder 10. The cushion spring 51 is made of iron. The eraser holder 43 is press-fitted into the rear interior of the lead tank 46. The eraser holder 43 is made of iron. The eraser 44 is positioned to erase the writing of the mechanical pencil 1. The eraser 44 is made of thermoplastic elastomer. The eraser stopper plate 45 is positioned to fix the eraser 44 in a suitable position for erasing the writing. The eraser stopper plate 45 is fixed to the outside of the eraser 44. The eraser stopper plate 45 is locked to the rear interior end of the eraser holder 43. The eraser stopper plate 45 is made of iron.The knock 42 is positioned to protect the eraser 44. The knock 42 is fixed to the rear outside of the eraser holder 43 by fitting. The knock 42 is made of brass. The knock cover 41 is positioned so that a finger or the like can touch it when the operating body 40 is advanced by external input such as a finger. The knock cover 41 is fixed to the rear outside of the knock 42. The knock cover 41 is made of brass. Note that this embodiment is just an example, and each of these may be made of a different material than described above. The locking device 48, the intermediate member 47, the core 49, and the lead tank 46 may be made of metal instead of resin. The knock spring 50, the cushion spring 51, the eraser holder 43, and the eraser stopper plate 45 may be made of a metal other than iron, or they may be made of resin. The eraser 44 does not have to be a thermoplastic elastomer, and any material that can erase writing lines is acceptable. The knock 42 and knock cover 41 may be made of a metal other than brass, or they may be made of resin. The operating body 40 can be any structure that allows the cylindrical body 32 or chuck 31 to be advanced by operating on a member exposed from the shaft 10. It is not limited to a structure called a "rear-end knock type" that presses on a member exposed from the rear end, as in this embodiment. For example, a window opening is provided on the outer surface of the shaft 10, and the cylindrical body 32 or chuck 31 can be advanced by operating on a member exposed from the window. A structure that operates by pressing on a member exposed from the window is called a "side knock type," and a structure that operates by moving the member exposed from the window along the axial direction is called a "side slide type." In addition, it is also possible to have a structure that can advance the cylindrical body 32 or chuck 31 by transmitting input from an external source, not limited to pressing. For example, a weight can be provided inside, and by swinging it axially, the weight can be moved back and forth, and it can perform the same role as the operating body.

[0019] Next, with reference to Figures 1 to 4, the operation of the mechanical pencil 1 of one embodiment of the present invention in the writing-ready state will be described. As shown in Figure 1 or Figure 2, when the tip pipe 22 protrudes from the front end of the tip metal 21, the front end of the lead 70 is located near the front end of the tip pipe 22, the lead 70 is gripped by the chuck 31, and the lead 70 is held by the stopper 28, when the lead 70 and the tip pipe 22 are simultaneously brought into contact with the paper surface, the lead 70 is gripped by the chuck 31 and can receive the writing pressure, so that writing is possible while wearing down the lead 70. This state is referred to as the "writing-ready state". As writing continues, the lead 70 rubs against the paper surface and wears down due to the writing pressure, and at the same time, the tip pipe 22 and the slider 23 to which the tip pipe 22 is press-fitted and fixed retract relative to the tip metal 21. At this time, the tip spring 25, which is located between the slider 23 and the tip metal ring 26, shortens by the amount that the slider 23 retracts. When writing stops, the pressure on the writing surface is removed, causing the shortened tip spring 25 to extend. At this time, the lead 70 is held in place by the stopper 28, which is press-fitted and fixed inside the slider 23. As the slider 23 moves forward under the biasing force of the tip spring 25, the lead 70 also moves forward. As mentioned above, the chuck set 30 allows the lead 70 to move forward, so as a result, the lead 70 moves forward while maintaining its relative position to the tip pipe 22, and writing becomes possible again. Thereafter, the same operation is repeated until the rear end of the lead 70 is no longer gripped by the chuck 31 after it has continued to move forward.

[0020] Next, with reference to Figures 1 to 4, the lead extension operation of the mechanical pencil 1 of the present invention when it is in a non-writing state will be explained. When the lead 70 is not gripped by the chuck 31 and is not held by the stopper 28, even though the tip pipe 22 is protruding from the front end of the tip metal 21, or when the lead 70 is not gripped by the chuck 31 and is held only by the stopper 28, even if the tip pipe 22 is brought into contact with the paper surface, the lead 70 cannot be gripped by the chuck 31 and cannot receive writing pressure, so the lead 70 cannot be worn down. As a result, writing is impossible, and this is referred to as the "non-writing state". In order to transition from this state to the writing state, it is necessary to advance the chuck set 30 and the chuck 31 via the operating body 40 and advance the lead 70.

[0021] In the following instructions, the initial state will be described as the state in which the lead 70 has not yet reached the chuck 31. When the knock cover 41 of the operating body 40, which is exposed from the rear end of the barrel 10, is pressed with a finger or the like, the entire chuck set 30 moves forward as a single unit via the knock 42, eraser holder 43, lead tank 46, intermediate member 47, and locking device 48. The chuck set 30 can move forward until it contacts the rear end of the tip ring 26 of the tip member 20. If the pressure on the operating body 40 continues, the recess provided on the outer circumference of the intermediate member 47 disengages from the protrusion provided on the inner circumference of the locking device 48, and the intermediate member 47 begins to move forward while sliding against the locking device 48. Once the intermediate member 47 has moved forward until it contacts the rear end of the chuck 31, the chuck 31 is then moved forward. As the chuck 31 moves forward, the external force acting on the chuck 31 from the cylindrical body 32 decreases due to the aforementioned wedge effect, and the elastic force of the chuck 31 itself causes the divided portion 31a to expand radially outward. As a result, the inner diameter of the gripping portion 31c1 may become larger than the outer diameter of the lead 70. At this time, if the tip member 20 of the mechanical pencil 1 is facing vertically downward, the lead 70 housed in the lead tank 46 passes through the gripping portion 31c1 of the chuck 31 and falls under its own weight to the rear end of the stopper 28 of the tip member 20. After that, the intermediate member 47 and the chuck 31 can move forward until the lead tank 46 and the locking device 48 come into contact, but they cannot press the operating body 40 any further. When the pressure on the operating body 40 is released from there, each component returns to its initial position as if reversing the operation during pressing. However, at this point, the core 70 has already passed the gripping portion 31c1 of the chuck 31, so the chuck 31 grips the core 70 with the tip of the core 70 in contact with the rear end of the stopper 28.

[0022] Next, when the operating body 40 is pressed again, the entire chuck set 30 moves forward as a single unit via the knock 42, eraser holder 43, lead tank 46, relay member 47, and locking device 48, as described above. At this time, since the chuck 31 is already gripping the lead 70, the chuck set 30 and the lead 70 try to move forward together. When the lead 70 enters the inside of the stopper 28 from the rear end of the stopper 28, it encounters resistance from the stopper 28. However, as described above, the chuck set 30 operates to prevent the lead 70 from moving backward. Therefore, it overcomes the resistance from the stopper 28, and the lead 70 moves forward together with the chuck set 30. It is also possible to continue pressing the operating body 40 from this state, but since it does not involve feeding the lead 70 from here on, the explanation is omitted. When the pressure on the operating body 40 is released after the lead 70 has moved forward, each component tries to return to its initial state, as if reversing the operation during pressing, as described above. However, at this point, the lead 70 has already entered the inside of the stopper 28 and is held in place by the stopper 28. Therefore, the lead 70 tries to move forward relative to the retraction of the chuck set 30. As mentioned above, the chuck set 30 operates in a way that allows the lead 70 to move forward. As a result, the holding force of the stopper 28 keeps the lead 70 in place, and only the chuck set 30 returns to its initial position. Consequently, comparing the position before and after pressing, the lead 70 moves forward by the amount the chuck set 30 moves forward in this operation. The operation obtained by this series of operations is called the "lead advance operation," and by repeating this lead advance operation, the lead 70 can be gradually advanced. When the front end of the lead 70 is advanced to near the front end of the tip pipe 22, it can transition to the writing-ready state described above.

[0023] Note that writing is also impossible if the tip pipe 22 does not protrude from the front end of the tip 21, regardless of the position of the lead 70, but this case is referred to as the "portable state". When in the portable state, it is necessary to press the operating body 40 and press the rear end of the slider 23 with the front end of the chuck stopper 35 via the chuck set 30. When the slider 23 is pressed and the locking between the O-ring 24 and the tip ring 26 is released, the slider 23 is biased forward by the tip spring 25. Then the tip pipe 22 protrudes from the front end of the tip 21. At this time, if the lead 70 was in the stopper 28 when in the portable state, the stopper 28 also moves along with the biasing of the slider 23. Therefore, the lead 70, which is being held by the stopper 28, also tries to move forward from the chuck set 30. As mentioned above, the chuck set 30 operates in a way that allows the lead 70 to move forward. Therefore, as the tip pipe 22 protrudes, the lead 70 also moves forward. After that, the pen can be switched to a writing-ready state by the lead-extending operation described above. If the lead 70 is not engaged with the stopper 28 when the pen is in the carrying state, the pen can be switched to a writing-ready state by the operation described above from the non-writing state, so the explanation is omitted. Conversely, the pen can be switched to the carrying state from either the writing-ready state or the non-writing state. Press the operating body 40 to advance the chuck 31 and release the gripping force on the lead 70. In this state, pressing the tip pipe 22 against the paper surface, etc., allows the lead 70 to retract relative to the chuck 31 and the slider 23 to retract. Since an O-ring 24 is attached to the outer circumference of the slider 23, when the O-ring 24 enters the tip ring 26, it locks in place and maintains its position. By switching to the carrying state in this way, breakage of the tip pipe 22 can be prevented. Therefore, the ease of use when carrying the pen is improved.

[0024] Next, with reference to Figures 5 to 36, the chuck 31 of the mechanical pencil 1 according to one embodiment of the present invention will be described in detail. Furthermore, Figures 1 to 4 mentioned above will be referenced as appropriate.

[0025] Figure 5 is a perspective view showing the appearance of the chuck 31 of a mechanical pencil 1 according to one embodiment of the present invention. Figure 6 is a longitudinal cross-sectional view along the axial direction showing one cross-section of the chuck 31 shown in Figure 5. Figure 7 is a longitudinal cross-sectional view rotated 90° around the axis from Figure 6. Figure 8 is a rear view showing the groove-forming surface 31d1 of the chuck 31 shown in Figure 5. Figure 9 is a partially enlarged view showing part C (groove portion 31d of the chuck 31) in Figure 6 in the case of one embodiment 1 of the present invention. Figure 10 is a partially enlarged view showing part C (groove portion 31d of the chuck 31) in Figure 6 in the case of one embodiment 2 of the present invention. Figure 11 is a partially enlarged view showing part C (groove portion 31d of the chuck 31) in Figure 6 in the case of one embodiment 3 of the present invention. Figure 12 is a partially enlarged view showing part C (groove portion 31d of the chuck 31) in Figure 6 in the case of one embodiment 4 of the present invention. Figure 13 is a rear view showing the groove-forming surface 31d1 of the chuck 31 in Figure 5 in the case of one embodiment 5 of the present invention. Figure 14 is a rear view showing the groove-forming surface 31d1 of the chuck 31 in Figure 5, in the case of Embodiment 6 of the present invention. Figure 15 is a rear view showing the groove-forming surface 31d1 of the chuck 31 in Figure 5, in the case of Embodiment 7 of the present invention. Figure 16 is a rear view showing the groove-forming surface 31d1 of the chuck 31 in Figure 5, in the case of Embodiment 8 of the present invention. Figure 17 is a rear view showing the groove-forming surface 31d1 of the chuck 31 in Figure 5, in the case of Embodiment 9 of the present invention. Figure 18 is a rear view showing the groove-forming surface 31d1 of the chuck 31 in Figure 5, in the case of Embodiment 10 of the present invention. Figure 19 is a rear view showing the groove-forming surface 31d1 of the chuck 31 in Figure 5, in the case of Embodiment 11 of the present invention. Figure 20 is a rear view showing the groove-forming surface 31d1 of the chuck 31 in Figure 5, in the case of Embodiment 12 of the present invention. Figure 21 is a partially enlarged view showing part C (groove 31d of the chuck 31) in Figure 6, according to Embodiment 13 of the present invention. Figure 22 is a partially enlarged view showing part C (groove 31d of the chuck 31) in Figure 6, according to Embodiment 14 of the present invention. Figure 23 is a partially enlarged view showing part C (groove 31d of the chuck 31) in Figure 6, according to Embodiment 15 of the present invention. Figure 24 is a partially enlarged view showing part C (groove 31d of the chuck 31) in Figure 6, according to Embodiment 16 of the present invention. Figure 25 is a partially enlarged view showing part C (groove 31d of the chuck 31) in Figure 6, according to Embodiment 17 of the present invention.Figure 26 is a longitudinal cross-sectional view along the axial direction of the chuck 31 in Figure 5, according to Embodiment 18 of the present invention. Figure 27 is a partially enlarged view showing part C (groove 31d of the chuck 31) in Figure 6, according to Embodiment 19 of the present invention. Figure 28 is a partially enlarged view showing part C (groove 31d of the chuck 31) in Figure 6, according to Embodiment 19 of the present invention. Figure 29 is a partially enlarged view showing part C (groove 31d of the chuck 31) in Figure 6, according to Embodiment 20 of the present invention. Figure 30 is a rear view showing the groove-forming surface 31d1 of the chuck 31 in Figure 5, according to Embodiment 21 of the present invention. Figure 31 is a rear view showing the groove-forming surface 31d1 of the chuck 31 in Figure 5, according to Embodiment 22 of the present invention. Figure 32 is a rear view showing the groove-forming surface 31d1 of the chuck 31 in Figure 5, according to Embodiment 23 of the present invention. Figure 33 is a rear view showing the groove-forming surface 31d1 of the chuck 31 in Figure 5, in the case of Embodiment 24 of the present invention. Figure 34 is a rear view showing the groove-forming surface 31d1 of the chuck 31 in Figure 5, in the case of Embodiment 25 of the present invention. Figure 35 is a rear view showing the groove-forming surface 31d1 of the chuck 31 in Figure 5, in the case of Embodiment 26 of the present invention. Figure 36 is a rear view showing the groove-forming surface 31d1 of the chuck 31 in Figure 5, in the case of Embodiment 27 of the present invention.

[0026] In the chuck 31 of the mechanical pencil 1 of one embodiment of the present invention, as shown in Figures 5 to 36, there is a groove-forming surface 31d1 perpendicular to the central axis of the hole 31c inside the chuck 31. The groove-forming surface 31d1 has a groove portion 31d that opens radially outward. The groove portion 31d includes a configuration that includes mutually opposing wall portions 31d2 and a bottom portion 31d3 that connects the wall portions 31d2.

[0027] As shown in Figures 5 to 36, the external shape of the chuck 31 of the present invention is basically a substantially cylindrical shape. The chuck 31 has a substantially cylindrical hole 31c that extends from the front end to the rear end on its inside. The chuck 31 has a divided portion 31a, in which the front part is divided into at least two or more parts. Hereafter, using the chuck 31 shown in Figures 5 to 36 as an example, the rear part will be described as having a joined shape, a joined portion 31b, but the rear part does not necessarily have to be joined, and depending on the embodiment, the rear part may also remain divided. If the rear part remains divided, that is, if the chuck 31 is composed of two or more pieces, all the constituent pieces together will be treated as one chuck 31. Also, although the number of divisions in the front part will be described as two, the number of divisions may be three or more depending on the embodiment. If the number of divisions is three or more, the aforementioned balls 33 may be arranged in a number corresponding to the number of divisions.

[0028] As shown in Figures 5 and 6, the front split portion 31a of the chuck 31 is equipped with a gripping portion 31c1 that has the function of gripping and releasing the core 70. As shown in Figure 6, the gripping portion 31c1 has the smallest inner diameter at the inner hole 31c of the chuck 31. The gripping portion 31c1 is connected to the rear inner circumferential surface 31c5 by an inner front tapered surface 31c4 that widens towards the rear. A helical groove 31c2 is carved into the gripping portion 31c1 to improve the gripping performance of the core 70. The groove cross-section of the helical groove 31c2 is trapezoidal, with the longer side of the trapezoid positioned inward. By carving this helical groove 31c2, a helical ridge 31c3 is formed on the gripping portion 31c1. With this helical ridge 31c3, the contact points with the core 70 are increased compared to when there is no ridge, so a stronger gripping force can be applied to the core 70. As shown in Figure 5, the outermost outer surface 31a1 on the divided portion side of the front divided portion 31a of the chuck 31 is provided with a recess 31a2 for positioning a ball 33. The recess 31a2 has a semi-ellipsoidal shape with a roughly elliptical cross-section, where the radius of curvature is smaller towards the front and larger towards the rear, with the axial middle of the recess 31a2 as the dividing point. At the front end of the front divided portion 31a of the chuck 31, a stepped portion 31a3 is provided, which has a smaller outer diameter than the outermost outer surface 31a1 on the divided portion side, further forward from the outermost outer surface 31a1 on the divided portion side where the recess 31a2 is provided. This stepped portion is connected to the front end surface of the chuck 31, and the front end surface is connected to the inner hole 31c of the chuck 31 shown in Figure 6. In the chuck 31 shown in Figure 5, a tapered surface 31a4 is provided at the rear of the outermost outer surface 31a1 on the division side of the front division portion 31a, and the tapered surface 31a4 is provided, which tapers to the rear and has a smaller outer diameter than the outermost outer surface 31a1 on the division side. This tapered surface 31a4 is connected to a roughly cylindrical intermediate portion 31a5 on the division side, as shown in Figure 7. The intermediate portion 31a5 is connected to the intermediate portion 31b1 on the joint side at the end of the division portion 31a. The division portion 31a and its intermediate portions shown in Figure 5 form a cantilever beam with the division portion 31a as the free end and the joint portion 31b as the fixed end. When an external force is applied to the chuck 31 and a gripping force is generated, this cantilever beam is deflected.When the external force is removed and the gripping force is released, an elastic force acts to eliminate the deflection. The lengths of the divided portion 31a and the intermediate portion of the chuck 31 of the present invention are set so that this force is appropriate. To the rear of the intermediate portion 31b1 on the joint side shown in Figure 7, there is a joint-side tapered surface 31b2 that widens towards the rear as shown in Figure 5, and the joint-side tapered surface 31b2 is connected to a joint-side stepped portion 31b3 shown in Figure 5, which has a larger outer diameter than the intermediate portion 31b1 on the joint side shown in Figure 7. Further rear from the joint-side stepped portion 31b3, there is a joint-side outermost surface 31b4 which has a larger outer diameter than the joint-side stepped portion 31b3. At the rear end of the joint portion 31b of the chuck 31, there is a groove-forming surface 31d1 shown in Figure 8, which is perpendicular to the central axis of the hole 31c shown in Figure 6. The groove-forming surface 31d1 is connected to the outermost outer surface 31b4 on the joint side shown in Figure 5, and also to the inner rear tapered surface 31c6 that tapers forward toward the inner circumferential surface 31c5 of the inner hole 31c of the chuck 31 shown in Figure 6. The groove-forming surface 31d1 shown in Figure 8 has a groove 31d that opens radially outward, and the groove 31d is composed of opposing wall surfaces 31d2 and a bottom surface 31d3 that connects the wall surfaces 31d2. The groove 31d is formed by partially cutting away the groove-forming surface 31d1, the outermost outer surface 31b4 on the joint side shown in Figure 5, the stepped portion 31b3 on the joint side, and the tapered surface 31b2 on the joint side shown in Figure 6. The opposing wall surfaces 31d2 shown in Figure 8 are in a positional relationship parallel to each other, and are both formed in a positional relationship perpendicular to the bottom surface 31d3.

[0029] Next, the assembly process of the chuck set 30 described above will be explained with reference to Figures 4 to 8. In the assembly process of the chuck set 30, as shown in Figure 4, it is necessary to properly position the balls 33 between the recess 31a2 of the chuck 31 and the cylindrical body 32. As shown in Figure 6, the recess 31a2 of the chuck 31 is provided only on the outermost outer surface 31a1 on the divided part side of the chuck 31, so the direction in which the balls 33 can be positioned in the circumferential direction of the chuck 31 is limited. To efficiently position the balls 33 in the assembly process, an assembly jig is used. However, since the direction in which the balls 33 can be positioned relative to the chuck 31 is limited, it is necessary to position and orient the chuck 31 relative to the assembly jig. Positioning is defined as setting the relative positional relationship between two parts to an arbitrary position, and orienting is defined as setting the relative angle between two parts to an arbitrary angle. Both positioning and orienting of the chuck 31 and the assembly jig can be achieved by bringing the chuck 31 and the assembly jig into contact. The shape of the assembly jig thereafter may be an extruded shape with any cross-sectional shape extending along an axis parallel to the central axis of the chuck 31. In addition, the following explanation assumes that the insertion direction of the assembly jig is limited to the front-rear direction along the central axis of the chuck 31. First, as mentioned above, the outer shape of the chuck 31 is basically cylindrical and has a roughly cylindrical hole 31c that penetrates from the front end to the rear end on the inside. Therefore, by making either the outer circumferential surface of the cylindrical shape of the outer shape of the chuck 31 externally tangent to the inner circumferential surface of the cylindrical shape provided in the assembly jig, or by making the inner cylindrical hole 31c of the chuck 31 shown in Figure 6 internally tangent to the outer circumferential surface of the cylindrical shape provided in the assembly jig, radial positioning between the chuck 31 and the assembly jig becomes possible, and the direction of movement of the chuck 31 can be limited to either the circumferential direction or the front-rear direction. Next, as shown in Figure 5 or Figure 8, by bringing any surface of the chuck 31 perpendicular to the central axis into contact with a surface provided on the assembly jig, it becomes possible to position the chuck 31 in the front-to-back direction relative to the assembly jig, and the movement direction of the chuck 31 can be limited to the circumferential direction only. As before, determining the circumferential direction requires a shape within the chuck 31 that can contact the assembly jig in the circumferential direction, and such a shape is referred to as the "circumferential direction determining shape".If the outer shape and inner hole 31c of the chuck 31 are both perfectly cylindrical, then circumferential contact is impossible regardless of the shape of the assembly jig. Therefore, such a chuck 31 can be said to lack a circumferential orientation-determining shape. Conversely, if circumferential contact is possible, then circumferential orientation determination is possible regardless of the shape. As shown in Figure 6 or Figure 8, the chuck 31 of the present invention has a groove portion 31d formed on a groove-forming surface 31d1 perpendicular to the central axis of the inner hole 31c of the chuck 31, which opens radially outward. The groove portion 31d includes opposing wall portions 31d2 and a bottom portion 31d3 connecting the wall portions 31d2. Therefore, by rotating the chuck 31 or the assembly jig and bringing the assembly jig into contact with the wall portions 31d2 of the groove portion 31d, circumferential orientation determination becomes possible. By positioning and determining the orientation in this way, the relative position and angle between the chuck 31 and the assembly jig can be limited. In this state, the chuck set 30 can be assembled by positioning the ball 33 in the direction of the recess 31a2 of the chuck 31 shown in Figure 5. In the assembly process, assembly is possible as long as all positioning and orientation are completed in the end, so the order of positioning and orientation is not limited to the above and can be any order.

[0030] Furthermore, as shown in Figure 8, the chuck 31 of the present invention has a circumferential direction-determining shape that is a groove 31d opening radially outward as described above. When considering a circle centered on the central axis of the chuck 31, when determining the circumferential direction, if the contact point between the chuck 31 and the assembly jig is positioned as far from the center as possible, the circumferential angular misalignment between the chuck 31 and the assembly jig can be reduced. This is because, firstly, in the case of concentric circles with the same center, the circumference is expressed as radius × 2 × pi, so the larger the radius, the larger the circumference. Secondly, since the wall surfaces 31d2 that constitute the groove 31d of the chuck 31 are parallel to each other, the shortest distance between the wall surfaces 31d2 is always constant, and this distance will hereafter be referred to as the "width W of the groove 31d". When attempting to place an assembly jig smaller than the width of the groove 31d in the groove 31d, the difference obtained by subtracting the width of the assembly jig from the width W of the groove 31d affects the possible circumferential angular misalignment. Here, the circumferential angular misalignment is expressed by Equation 1 below. As mentioned above, the "width W of the groove 31d and the width of the assembly jig" that constitute the difference are constant, so the arc length, which is the numerator of Equation 1, is constant, while the circumference, which is the denominator of Equation 1, increases with the radius from the central axis. In other words, if the contact point between the chuck 31 and the assembly jig is positioned as far from the center as possible and the radius is increased, the denominator of Equation 1 increases, and the circumferential angular misalignment decreases. Therefore, as shown in Figure 8, by making the circumferential determining shape a groove 31d that opens radially outward, the contact point between the chuck 31 and the assembly jig can be positioned as far from the center as possible, thus minimizing the circumferential angular misalignment during circumferential determination. By suppressing the circumferential angular misalignment, the ball 33 can be reliably placed in the recess 31a2 of the chuck 31, thereby improving assembly efficiency and preventing assembly defects. (Formula 1)

[0031] TIFF2026116122000002.tif31154

[0032] In addition, as shown in Figure 8, making the circumferential direction-determining shape a groove 31d is expected to be effective even after the assembly process and when the chuck set 30 is assembled. As mentioned above, the part of the groove 31d that enables circumferential direction determination is the wall surface 31d2, and it is sufficient that the assembly jig can come into contact with the wall surface 31d2. In other words, as long as this condition is met, circumferential direction determination is possible without removing as much as possible from the outermost circumferential surface 31b4 on the joint side, as shown in Figure 5. In the assembled state, the inner circumferential surface of the cylindrical body 32 shown in Figure 4 is located outside the outermost circumferential surface 31b4 on the joint side, so a radial gap is created between them. This gap becomes larger the larger the circumference when the outermost circumferential surface 31b4 on the joint side is removed. Basically, the components that make up the mechanical pencil 1 are arranged along the axial direction, but in reality, the chuck 31 can move radially relative to the cylindrical body 32 by the amount of this gap, so there is a possibility that the central axis of the chuck 31 and the central axis of the cylindrical body 32 will be shifted radially. When writing with mechanical pencil 1, the chuck 31 holds the lead 70, so the central axes of the chuck 31 and the lead 70 are almost on the same line. On the other hand, the cylinder 32 is connected to the stopper 28 that makes up the tip member 20 via fitting, press-fitting, and screw connections to the operating body 40, the barrel 10, and the tip member 20. Therefore, the central axes of the cylinder 32 and the stopper 28 are almost on the same line. In other words, a radial misalignment between the central axis of the chuck 31 and the central axis of the cylinder 32 leads to a radial misalignment between the central axis of the lead 70 and the central axis of the stopper 28. When the central axis of the lead 70 and the central axis of the stopper 28 are misaligned, the resistance that the lead 70 receives from the stopper 28 increases when the lead 70 enters the stopper 28. If this resistance becomes greater than the frictional force acting between the chuck 31 and the lead 70, the lead 70 cannot be fed out. If the lead 70 cannot be fed out, the transition from the aforementioned non-writing state to the writing state becomes impossible, causing a malfunction. This malfunction is referred to as "deterioration of lead feeding." Therefore, by making the circumferential fixing shape a groove 31d, the outermost outer surface 31b4 on the joint side is removed as little as possible, and the gap between the chuck 31 and the cylinder 32 can be made as small as possible. This helps to suppress radial misalignment between the lead 70 and the central axis of the stopper 28, and as a result, it can be expected that deterioration of lead feeding will be suppressed.

[0033] As shown in Figure 8, the number of grooves 31d is equal to or greater than the number of divisions in front of the chuck 31 (in the case of Figure 8, it is the same number). In other words, by determining the number of grooves 31d based on the number of divisions in front of the chuck 31, an effect of improved assembly can be expected. For example, the purpose of determining the circumferential direction in the chuck 31 of this embodiment is to position the balls in the correct location. The number of balls 33 to be placed is the same as the number of divisions in the chuck 31, and the number of recesses 31a2 in the chuck 31 where the balls 33 are placed is also the same as the number of divisions in the chuck 31. Therefore, by using the number of divisions in the chuck 31 as the basis, the balls 33 can be appropriately oriented in the desired circumferential direction, resulting in good assembly. Furthermore, as shown in Figures 9 to 12, if the grooves 31d are configured to be recessed at least in the axial direction, the grooves 31d can function as a circumferential direction determining shape, which is preferable.

[0034] As shown in Figure 9, if the groove 31d is configured to open radially outward, the contact point between the chuck 31 and the assembly jig can be positioned as far from the center as possible, as described above, which is expected to improve the accuracy of circumferential orientation. In addition, if the groove 31d is configured to penetrate axially, the aforementioned assembly jig can be easily guided into the groove 31d, which is expected to speed up circumferential orientation.

[0035] As shown in Figure 10, if the radially outer side of the groove 31d is configured to be closed, the outermost outer surface 31b4 on the joint side is not machined at all, and the gap between the chuck 31 and the cylindrical body 32 can be made as small as possible. As a result, the deterioration of centering can be further suppressed as described above. In addition, if the groove 31d is configured to penetrate in the axial direction, the assembly jig can be easily guided into the groove 31d, and the circumferential orientation can be determined more quickly.

[0036] As shown in Figure 11, configuring the groove 31d to open radially outward allows the contact point between the chuck 31 and the assembly jig to be positioned as far from the center as possible, thus improving the accuracy of circumferential orientation. In addition, configuring the groove 31d to be closed on either the axial side prevents the assembly jig from entering from the closed side, thus preventing errors in assembly direction.

[0037] As shown in Figure 12, if the radially outer side of the groove 31d is configured to be closed, the outermost outer surface 31b4 on the joint side is not machined at all, and the gap between the chuck 31 and the cylindrical body 32 can be made as small as possible, thus suppressing the deterioration of centering as described above. In addition, if one of the axial sides of the groove 31d is also configured to be closed, it prevents the assembly jig from entering from the closed side, thus preventing errors in the assembly direction.

[0038] As shown in Figure 13, the wall portions 31d2 of the groove portion 31d are in direct contact with each other, and if the connection is configured to be substantially linear in the axial direction, that is, without a bottom portion 31d3 in the groove portion, then compared to the case where it is substantially planar, that is, with a bottom portion 31d3 in the groove portion, a faster determination of circumferential direction can be expected. As mentioned above, circumferential direction is determined by contact between the assembly jig and the wall portion 31d2, but if there is a bottom portion in the groove portion, there is a possibility that the assembly jig will come into contact with the bottom portion 31d3 before the wall portion 31d2. If it is substantially linear, such a possibility can be eliminated, so a faster determination of circumferential direction can be expected.

[0039] As shown in Figure 13, if the wall surface 31d2 of the groove 31d is configured to be flat, when the assembly jig comes into contact with the wall surface 31d2, it becomes a point contact in cross-section, thus suppressing wear caused by contact, and a wear suppression effect on the assembly jig and the groove 31d can be expected. The assembly jig can have any cross-sectional shape, but for example, if it is the simplest circular shape, and the wall surface 31d2 is flat, the contact between the assembly jig and the wall surface 31d2 will always be a point contact. Surface contact occurs only when the cross-sectional shape of the assembly jig has a straight line that is perfectly parallel to the wall surface 31d2, but when actually determining the direction, if a gap is not provided between the assembly jig and the wall surface 31d2, the assembly jig will not be able to easily enter the groove 31d in the first place. Since the chuck 31 rotates when determining the circumferential direction, the wall surface 31d2 also rotates. Because the chuck 31 is rotatable due to the provided gap, the relative angle between the assembly jig and the wall portion 31d2 is constantly changing. The possibility that the cross-sectional shape of the assembly jig will always be a straight line perfectly parallel to the wall portion 31d2 is extremely low, and in most cases it will be point contact. Therefore, if the wall portion 31d2 is configured to be flat, a wear suppression effect on the assembly jig and the groove portion 31d can be expected.

[0040] As shown in Figure 14, if the wall surface 31d2 of the groove 31d is configured to be curved, the stress generated inside the chuck 31 in response to the external force applied to the chuck 31 when the assembly jig comes into contact with the wall surface 31d2 can be distributed by the curved surface near the connection point of the wall surface 31d2, thus providing an effect of preventing damage to the groove 31d.

[0041] As shown in Figure 15, if the wall surface 31d2 of the groove 31d is composed of at least two surfaces, and each surface is configured such that the angle with respect to the tangent plane P at the intersection of the wall surface 31d2 and the outermost outer surface 31b4 on the joint side is different from that of the other surfaces, then when the chuck 31 rotates, it is possible to set a circumferential direction that is easy to determine and a circumferential direction that is difficult to determine. When these angles are different, the angle at which the assembly jig and the wall surface collide will be different. For example, when the assembly jig comes into contact with the wall surface that is closer to perpendicular, the assembly jig collides relatively head-on with the wall surface, so the force is less likely to escape. On the other hand, when the assembly jig comes into contact with the wall surface that is further away from perpendicular, the contact will be relatively oblique, so the force escapes in the direction perpendicular to the circumferential direction (radially outward), and when the force escapes radially, the assembly jig will move in a direction away from the groove 31d. In other words, as a result, the assembly jig is less likely to come off one wall section 31d2 (making it easier to determine the circumferential direction), while it is more likely to come off the other wall section 31d2 (making it more difficult to determine the circumferential direction), thus allowing for a directional approach to determining the circumferential direction. By allowing for a directional approach to determining the circumferential direction, an effect of preventing errors in the assembly direction can be expected.

[0042] As shown in Figures 13 to 15, if the groove 31d is configured such that the distance between the surfaces constituting the wall portion 31d2 increases from the radially inward to the radially outward direction, the assembly jig can be more easily inserted into the groove 31d, which is expected to speed up the determination of the circumferential direction.

[0043] As shown in Figures 16 to 20, if the groove portion 31d is configured such that the connection between the wall portions 31d2 is substantially planar, the connection portion, i.e., the bottom portion 31d3, can guide the assembly jig and correct radial positional misalignment, which is expected to improve the accuracy of radial direction setting.

[0044] As shown in Figures 17 to 20, if the groove 31d is configured such that the wall surface 31d2 is flat, when the assembly jig comes into contact with the wall surface 31d2, it becomes a point contact in cross-section, thus suppressing wear caused by contact, and a wear suppression effect on the assembly jig and groove 31d can be expected. The assembly jig can have any cross-sectional shape, but for example, if it is the simplest circular shape, and the wall surface 31d2 is flat, the contact between the assembly jig and the wall surface 31d2 will always be a point contact. Surface contact occurs only when the cross-sectional shape of the assembly jig has a straight line that is perfectly parallel to the wall surface 31d2, but when actually determining the direction, if a gap is not provided between the assembly jig and the wall surface 31d2, the assembly jig will not be able to easily enter the groove 31d in the first place. Since the chuck 31 rotates when determining the circumferential direction, the wall surface 31d2 also rotates. Because the chuck 31 is rotatable due to the provided gap, the relative angle between the assembly jig and the wall portion 31d2 is constantly changing. The possibility that the cross-sectional shape of the assembly jig will always be a straight line perfectly parallel to the wall portion 31d2 is extremely low, and in most cases it will be point contact. Therefore, if the wall portion 31d2 is configured to be flat, a wear suppression effect on the assembly jig and the groove portion 31d can be expected.

[0045] As shown in Figure 16, if the groove portion 31d is configured such that the wall portion 31d2 is curved, the stress generated inside the chuck 31 in response to the external force applied to the chuck 31 when the assembly jig comes into contact with the wall portion 31d2, and extending from the wall portion 31d2 to the connection portion, i.e., near the bottom portion 31d3, can be distributed by the curved surface, thus providing an effect of preventing damage to the groove portion 31d.

[0046] As shown in Figure 17, if the wall surface 31d2 of the groove 31d is composed of at least two surfaces, and each surface is configured such that the angle with respect to the tangent plane P at the intersection of the wall surface 31d2 and the outermost outer surface 31b4 on the joint side is different from that of the other surfaces, then when the chuck 31 rotates, it is possible to set a circumferential direction that is easy to determine and a circumferential direction that is difficult to determine. When these angles are different, the angle at which the assembly jig and the wall surface collide will be different. For example, when the assembly jig comes into contact with the wall surface with the more obtuse angle, the force escapes in the direction perpendicular to the circumferential direction (radially inward), and the assembly jig moves in a direction that makes it difficult to dislodge from the groove 31d. On the other hand, when the assembly jig comes into contact with the wall surface with the more acute angle, the force escapes in the direction perpendicular to the circumferential direction (radially outward), and the assembly jig moves in a direction that makes it difficult to dislodge from the groove 31d. In other words, as a result, the assembly jig is less likely to come off one wall section 31d2 (making it easier to determine the circumferential direction), while it is more likely to come off the other wall section 31d2 (making it more difficult to determine the circumferential direction), thus allowing for a directional approach to determining the circumferential direction. By allowing for a directional approach to determining the circumferential direction, an effect of preventing errors in the assembly direction can be expected.

[0047] As shown in Figure 18, if the groove 31d is configured such that the distance between the surfaces constituting the wall portion 31d2 changes discontinuously at least one point, the circumferential angle can be changed according to the arrangement of the assembly jig. Depending on whether the assembly jig is positioned to contact the side with the larger distance or the side with the smaller distance, the angle at which the circumferential direction is determined will change even if the assembly jig has the same cross-sectional shape. This makes it possible to incorporate processes that require multiple circumferential angle determinations for the same part, and is expected to increase the flexibility of the assembly method.

[0048] As shown in Figure 19, if the groove 31d is configured such that the distance between the surfaces constituting the wall portion 31d2 increases from the radially inward to the radially outward direction, the assembly jig can easily enter the groove 31d, which is expected to speed up the determination of the circumferential direction.

[0049] As shown in Figure 20, if the groove 31d is configured such that the distance between the surfaces constituting the wall surface 31d2 decreases from the radially inward to the radially outward direction, then after the assembly jig enters the groove 31d, the areas where the distance between the surfaces decreases towards the radially outward direction will suppress the assembly jig from coming off radially, thus reducing the likelihood of failure in circumferential orientation determination.

[0050] As shown in Figures 21 and 22, if the groove 31d is configured such that its depth is the same at least at the axial front end and the axial rear end, the assembly jig will be able to enter the groove 31d to a similar extent from either the front or rear direction of the chuck 31. This allows the user to choose which direction to position the assembly jig in relative to the chuck 31, which is expected to increase the design flexibility of the assembly jig.

[0051] As shown in Figures 23 and 24, configuring the bottom surface portion 31d3 of the groove 31d to have different depths in the front-rear direction of the chuck 31 makes it easier to guide the assembly jig into the groove 31d and is expected to reduce radial misalignment. As mentioned above, the assembly jig is an extruded shape with an arbitrary cross-sectional shape that extends along an axis parallel to the central axis of the chuck 31. Therefore, when attempting to position the chuck 31 in the groove 31d during circumferential orientation determination, a radial gap is created between the bottom surface portion 31d3 that constitutes the groove 31d and the assembly jig. As mentioned above, positioning the contact point between the chuck 31 and the assembly jig as far from the center as possible is expected to suppress directional misalignment during circumferential orientation determination. However, the radial gap between the bottom surface portion 31d3 and the assembly jig causes radial misalignment, so it is desirable to make the bottom surface portion 31d3 shallower to reduce this gap in accordance with the contact point between the chuck 31 and the assembly jig. However, simply making the bottom portion 31d3 shallower makes it more difficult to insert the assembly jig into the groove portion 31d. Therefore, if the depth of the bottom portion 31d3 of the groove portion 31d is configured to differ in the front-rear direction of the chuck 31, the assembly jig can easily enter the groove portion 31d from the deeper side D1. In addition, if the assembly jig comes into contact with the bottom portion 31d3 of the groove portion 31d during the process of moving from the deeper side D1 to the shallower side D2, the assembly jig will be guided along the bottom portion 31d3 and move to the shallower side D2. Once it reaches the shallower side D2, the radial gap will be reduced by the shallower side D2, which is expected to reduce radial displacement.

[0052] As shown in Figure 23, if the bottom surface 31d3 of the groove 31d is configured to be deeper towards the front of the chuck 31, the deeper side D1 becomes the front side of the chuck 31, making it easier for the assembly jig to enter the groove 31d from the front. When the assembly jig can easily enter the groove 31d from the front, the assembly jig can be positioned on the front side of the chuck 31, increasing the design freedom for manufacturing the assembly jig. For example, by allowing the front of the chuck 31 to fall downwards with its own weight relative to the assembly jig, the chuck 31 can be naturally oriented or oriented with its front facing downwards, making it easier to position the ball 33 in the recess 31a2, which is expected to improve the ease of assembly.

[0053] As shown in Figure 24, if the bottom surface 31d3 of the groove 31d is configured to be deeper towards the rear of the chuck 31, the rear of the chuck 31 becomes the deeper side D1, making it easier for the assembly jig to enter the groove 31d from the rear. When the assembly jig can easily enter the groove 31d from the rear, the assembly jig can be positioned on the rear side of the chuck 31, increasing the design freedom for manufacturing the assembly jig. For example, by allowing the rear of the chuck 31 to fall downwards with its own weight relative to the assembly jig, the chuck 31 can be naturally oriented or oriented with its rear facing downwards, and as described above, it is expected that the ball 33 can be easily positioned in the recess 31a2, resulting in improved assembly efficiency.

[0054] As shown in Figures 23 and 24, it is more preferable to configure the groove portion 31d so that the difference in depth (D1-D2) of the bottom surface portion 31d3 of the groove portion 31d is between 0.1 mm and 0.7 mm. If the difference is 0.1 mm or more, a difference in depth can be reliably provided even when considering dimensional variations of the parts. In addition, in this embodiment, since the axial length L of the bottom surface portion 31d3 of the groove portion 31d is approximately 0.7 mm, if the difference in depth (D1-D2) of the bottom surface portion 31d3 of the groove portion 31d is 0.7 mm or less, the angle S of the inclined surface formed by the plane of the bottom surface portion 31d3 and the plane passing through the central axis and perpendicular to the depth direction of the groove portion 31d will be approximately 45° or less, making it easier for the assembly jig to enter the groove portion 31d, and thus an effect of speeding up circumferential direction setting can be expected.

[0055] As shown in Figure 25, if the groove 31d is configured to have a stepped portion in the axial direction, it is possible to determine the circumferential direction of different processes depending on the position of the assembly jig in the front or rear direction of the chuck 31. For example, if the assembly jig is positioned so that it can only be accessed in the direction of the deeper side of the groove 31d, it is impossible to access it in the direction of the shallower side of the groove 31d, thus preventing errors in the assembly direction.

[0056] As shown in Figure 26, configuring the bottom surface 31d3 of the groove 31d to be a single plane is preferable because it makes it less likely for the assembly jig to get caught when it enters the groove 31d. When the bottom surface 31d3 is a single plane, the bottom surface 31d3 becomes an inclined surface, and when the assembly jig enters the groove 31d, it is smoothly guided to the shallow side D2, and because it is less likely to get caught along the way, it is expected that the circumferential direction setting will be faster.

[0057] As shown in Figure 26, it is preferable to configure the inclined surface, formed by the plane of the bottom surface 31d3 of the groove 31d and the plane passing through the central axis and perpendicular to the depth direction of the groove 31d, to be 8° or more and 45° or less, because this allows the assembly jig to be smoothly guided when it enters the groove 31d. In the case of the chuck 31 of this embodiment, if the angle S of the inclined surface is 8° or more, the effect can be reliably obtained regardless of variations in the shape of the parts. Also, if the angle S of the inclined surface is 45° or less, the assembly jig can enter the groove 31d more easily, so the effect of faster circumferential direction setting can be expected.

[0058] As shown in Figures 27 to 29, configuring the connection portion of the groove 31d to be curved in the axial direction is preferable because it makes it less likely for the assembly jig to get caught when it enters the groove 31d. Because the assembly jig is less likely to get caught when it enters the groove 31d, it is expected that the circumferential direction setting will be faster.

[0059] As shown in Figures 27 and 28, it is preferable to have the bottom surface 31d3 of the groove 31d be a single concave surface, as this makes it less likely for the assembly jig to get caught when it enters the groove 31d. In particular, when the bottom surface 31d3 is a curved surface, especially a single concave surface, the assembly jig is less likely to come into contact with the bottom surface 31d3 near the entrance (deep side D1) when it enters the groove 31d from the deeper side D1 and exits from the shallower side D2 opposite to the entry side, and it is expected that wear of the assembly jig due to contact can be suppressed.

[0060] As shown in Figure 29, it is preferable to have the bottom surface 31d3 of the groove 31d composed of a single convex surface, as this makes it less likely for the assembly jig to get caught when it enters the groove 31d. In particular, when the bottom surface 31d3 is composed of a curved surface, especially a single convex surface, the assembly jig is less likely to come into contact with the bottom surface 31d3 near the exit on the shallow side D2 when it enters the groove 31d from the deeper side D1 and exits from the shallow side D2 opposite to the entry side, and it is expected that wear of the assembly jig due to contact can be suppressed.

[0061] As shown in Figures 27 to 29, configuring the curved surface of the bottom surface 31d3 of the groove 31d to have a radius of curvature R of 1 mm or more and 20 mm or less is preferable, as it ensures the effect of configuring the bottom surface 31d3 of the groove 31d as a single concave or convex surface, as described above. Generally, the smaller the radius of curvature R of a curved surface, the sharper the curved surface becomes, and the larger the R, the gentler the curved surface becomes, approaching a flat surface. In the case of the chuck 31 of this embodiment, if the R is dimensionally between 1 mm and 20 mm, the curved surface will have a reliable curvature that prevents the assembly jig from getting caught when it enters the groove 31d, thus suppressing wear of the jig due to contact.

[0062] As shown in Figures 27 to 29, if the bottom surface portion 31d3, which is the connection portion of the groove portion 31d, is configured to be curved in cross-section along the axial direction, the assembly jig is less likely to get caught when it enters the groove portion 31d, and thus it can be expected that the circumferential direction setting will be expedited.

[0063] As shown in Figure 30, if the bottom surface 31d3, which is the connection point of the groove 31d, is configured to be curved in cross-section along the radial direction, the stress generated inside the chuck 31 in response to the external force applied to the chuck 31 when the assembly jig comes into contact with the wall surface 31d2, and which occurs near the connection point of the wall surface 31d2, i.e., the bottom surface 31d3, can be distributed by the curved surface, thus providing an effect of preventing damage to the groove 31d.

[0064] As shown in Figure 8, configuring the number of grooves 31d to be the same as the number of divisions in front of the chuck 31 is preferable because it allows for circumferential orientation of the assembly jig as intended. In the case of the chuck 31 of this embodiment, as shown in Figure 5 or Figure 7, there are 2 divisions, and as shown in Figure 8, there are 2 grooves 31d. Therefore, the assembly jig has two opportunities to enter the grooves 31d per rotation, and in either of these instances, the chuck 31 can be expected to be oriented in accordance with the direction of the division 31a. Similarly, if the number of divisions is 3 or more, a similar effect can be obtained and is preferable if the number of grooves corresponds to that number.

[0065] As shown in Figure 31, configuring the chuck 31 so that the number of grooves 31d is greater than the number of divisions in front of it is preferable because it shortens the time required for circumferential orientation. In the case of the chuck 31 of this embodiment, if the number of divisions is 2 and the number of grooves 31d is 3 or more, the assembly jig will have the opportunity to enter the grooves 31d a number of times equal to the number of grooves 31d during one rotation. If the jig is configured so that assembly is possible regardless of when it enters the grooves, the time required to enter the grooves will decrease as the number of grooves 31d increases, and the effect of speeding up circumferential orientation can be expected.

[0066] As shown in Figures 8 and 31, when there are multiple grooves 31d, it is preferable to configure them so that they are point-symmetrical with respect to each other, as this allows for the intended circumferential orientation of the assembly jig. In the case of the chuck 31 of this embodiment, there are two grooves 31d, and they are point-symmetrical with respect to each other. Therefore, whether the assembly jig enters one groove 31d or the other groove 31d, the orientation of the divided portion 31a of the chuck 31 does not change. Thus, with this configuration, the chuck 31 can be oriented in accordance with the orientation of the divided portion 31a, which is preferable.

[0067] As shown in Figure 32, when there are multiple grooves 31d, it is preferable to configure them so that they are symmetrically positioned relative to each other, as this allows for the intended circumferential orientation to be determined relative to the assembly jig. In the case of the chuck 31 of this embodiment, there are two grooves 31d, and they are symmetrically positioned relative to each other. Therefore, when using two assembly jigs corresponding to this arrangement, the opportunity for all assembly jigs to enter the grooves 31d is limited to once per rotation. Thus, this configuration prevents circumferential orientation other than the intended one, and is expected to prevent assembly errors.

[0068] As shown in Figure 33, when there are multiple grooves 31d, it is preferable to configure them so that the arc lengths of the circumferences between the grooves 31d are different from each other, as this allows for the intended circumferential orientation to be determined for the assembly jig. For example, when there are three grooves 31d and the arc lengths of the circumferences between them are different, if three assembly jigs corresponding to that arrangement are used, all assembly jigs will only have the opportunity to enter the grooves 31d once per rotation. With such a configuration, it is possible to prevent orientation determination other than the intended direction, and an effect of preventing errors in assembly direction can be expected.

[0069] As shown in Figure 34, when there are multiple grooves 31d, if the dimensions of the edges constituting the grooves 31d differ at least one point, then by using multiple assembly jigs with different cross-sectional shapes corresponding to each groove 31d, assembly errors when determining multiple circumferential directions can be prevented. The dimensions of all edges may be different. The edges constituting the groove 31d include the wall surface 31d2 and connecting parts 31d3 of the groove 31d, and the dimensions of the edges include the length of the sides and arcs that make up the surface, the radius of curvature of the arcs, and the angles between the surfaces. If an assembly jig with a cross-sectional shape that can enter any one of the grooves 31d but cannot enter any of the other grooves 31d is used, the opportunity for that assembly jig to enter the groove 31d is limited to once per rotation, thus preventing direction determination other than the intended direction. Furthermore, if an assembly jig is used with a cross-sectional shape that allows it to enter a groove 31d different from the first groove 31d, but prevents it from entering the first groove 31d or other grooves 31d, the assembly jig will only have one opportunity to enter a groove 31d per rotation. However, it can be oriented in a different direction than the first groove 31d, which is expected to prevent assembly errors between the first and second grooves. In addition, if there are three or more grooves, a similar effect can be expected for the third and subsequent grooves.

[0070] As shown in Figure 8, if the distance W between the surfaces constituting the wall portion 31d2 of the groove is configured to be smaller than the minimum diameter of any cross-section of the rod-shaped lead 70, the lead 70 will not accidentally enter the groove portion 31d of the chuck 31 inside the assembled mechanical pencil 1. If the lead 70 enters the groove portion 31d of the chuck 31, it means that the lead 70 enters the internal space of the chuck set 30, which is surrounded by the cylindrical body 32, the chuck 31, and the chuck stopper 35, as shown in Figure 4. Since a spring is located in this internal space of the chuck set 30, if the lead 70 enters, it may induce the spring to expand or contract at an unintended timing. For example, the spring biases the chuck 31 backward relative to the cylindrical body 32, but if the spring shortens for such a reason and the backward biasing force weakens, the external force applied from the cylindrical body 32 to the chuck 31 via the ball 33 decreases. Consequently, the chuck 31 cannot apply sufficient gripping force to the lead 70, and as a result, it cannot withstand the writing pressure, which can unintentionally cause a malfunction that renders writing impossible. This malfunction cannot be resolved without removing the lead 70 from the internal space of the chuck set 30, and since this requires disassembly due to its structure, it becomes difficult to recover once this malfunction occurs. Therefore, a more preferable mechanical pencil 1 can be obtained by configuring the distance between the wall surfaces 31d2 of the groove 31d to be smaller than the diameter of the lead 70.

[0071] As shown in Figure 35, configuring the groove portion 31d so that the number of grooves 31d is less than the number of divisions in front of the chuck 31 reduces the effort required to form the groove portion 31d by additional machining, which is expected to improve productivity. Furthermore, as shown in Figure 10, configuring the groove portion 31d so that the radially outer side is closed allows the outermost surface 31b4 on the joint side to be left completely unmachined, minimizing the gap between the chuck 31 and the cylindrical body 32, thus suppressing the deterioration of centering as described above. In addition, configuring the groove portion 31d to penetrate axially makes it easier to guide the assembly jig into the groove portion 31d, which is expected to improve orientation.

[0072] As shown in Figure 36, configuring the groove portion 31d so that the number of groove portions 31d is less than the number of divisions in front of the chuck 31 reduces the effort required to form the groove portions 31d by additional machining, which is expected to improve productivity. Furthermore, as shown in Figure 11, configuring the groove portion 31d to open radially outward allows the contact point between the chuck 31 and the assembly jig to be positioned as far from the center as possible, as described above, which is expected to improve the accuracy of circumferential orientation. In addition, configuring the groove portion 31 to be closed on either the axial side prevents the assembly jig from entering from the closed side, which is expected to prevent errors in the assembly direction.

[0073] If the number of grooves 31d is configured to be less than the number of divisions in front of the chuck 31, the effort required to form the grooves 31d by additional machining will be reduced, and an improvement in productivity can be expected. Furthermore, if the radially outer side of the grooves 31d is configured to be closed, as shown in Figure 12, the outermost surface 31b4 on the joint side will not be machined at all, and the gap between the chuck 31 and the cylindrical body 32 can be made as small as possible, thus suppressing the deterioration of centering as described above. In addition, if one of the axial sides of the grooves 31d is configured to be closed, the entry of the assembly jig from the closed side will be prevented, thus preventing errors in the assembly direction. [Explanation of Symbols]

[0074] 1. Mechanical pencil 10 shaft cylinder 11 Front axle 12 rear axle 20 Front member 21 Gold tip 22 Tip pipe 23 Slider 24 O-rings 25 Tip spring 26 Gold-tipped ring 27 Retractor 28 Reversal stop 30 chuck set 31 Chuck 31a Split part 31a1 Outermost surface on split side 31a2 recess 31a3 Split part side step part 31a4 Tapered surface on the splitting section side 31a5 Intermediate part on the dividing section side 31b Joint 31b1 Intermediate part on joint side 31b2 Tapered surface on the joint side 31b3 Joint side step 31b4 Outermost surface on joint side 31c hole 31c1 Grip part 31c2 spiral groove 31c3 Spiral ridge 31c4 Inner front tapered surface 31c5 Inner surface 31c6 Inner rear tapered surface 31d Groove 31d1 Groove forming surface 31d2 Wall section 31d3 Bottom part 32 Cylinder 33 Ball 34 Chuck springs 35 Chuck Stopper 40 Operating Body 41 Knock Cover 42 knocks 43 Eraser holder 44 Erasers 45 Eraser holder 46-core tank 47. Intermediate component 48 Locking device 49 Core 50 knock springs 51 Cushion Spring 60 clips 70 cores D1 Deep side D2 Shallow side Axial length of groove 31d P tangent plane R: Radius of curvature of the uneven surface at the base. S Angle of the inclined surface Width of groove 31d

Claims

1. It consists of at least a cylindrical body, a chuck, and a spring. The cylindrical body is positioned radially outward from the chuck. The zipper has a hole that runs through from the front end to the back end on the inside. The front is divided into at least two or more sections. Inside the front divided section, there is a gripping section that has the function of gripping and releasing a rod-shaped object. It is positioned to be able to move back and forth relative to the cylindrical body. The spring biases the chuck backward. On the plane perpendicular to the central axis of the hole inside the chuck, A groove is formed that opens radially outward. The groove is recessed at least in the axial direction. The number of grooves is greater than or equal to the number of divisions in front of the chuck. A mechanism for extending a rod-shaped object.

2. The groove opens radially outward and penetrates axially. The rod-shaped body dispensing mechanism according to claim 1.

3. The groove portion is closed on its radially outer side and penetrates in the axial direction. The rod-shaped body dispensing mechanism according to claim 1.

4. The groove opens radially outward and is closed at one end in the axial direction. The rod-shaped body dispensing mechanism according to claim 1.

5. The groove portion is closed on the radially outer side and closed on either the axial side or the other side. The rod-shaped body dispensing mechanism according to claim 1.

6. The groove portion has a substantially linear connection between the wall surfaces. A rod-shaped body dispensing mechanism according to any one of claims 2 to 5.

7. The groove portion has a flat wall surface. The rod-shaped body dispensing mechanism according to claim 6.

8. The groove portion has a curved wall surface. The rod-shaped body dispensing mechanism according to claim 6.

9. The groove portion is composed of at least two wall surfaces, and each surface has a different angle with respect to the tangent plane at the intersection of the wall surface and the outermost surface. The rod-shaped body dispensing mechanism according to claim 6.

10. The groove portion is such that the distance between the surfaces constituting the wall portion is It increases from the radially inner side to the radially outer side. The rod-shaped body dispensing mechanism according to claim 6.

11. The groove portion has a substantially planar connection between the wall surfaces. A rod-shaped body dispensing mechanism according to any one of claims 2 to 5.

12. The groove portion has a flat wall surface. The rod-shaped body dispensing mechanism according to claim 11.

13. The groove portion has a curved wall surface. The rod-shaped body dispensing mechanism according to claim 11.

14. The groove portion is composed of at least two wall surfaces, and each surface has a different angle with respect to the tangent plane at the intersection of the wall surface and the outermost surface. The rod-shaped body dispensing mechanism according to claim 11.

15. The groove portion is such that the distance between the surfaces constituting the wall portion is At least one location changes discontinuously, The rod-shaped body dispensing mechanism according to claim 11.

16. The groove portion is such that the distance between the surfaces constituting the wall portion is It increases from the radially inner side to the radially outer side. The rod-shaped body dispensing mechanism according to claim 11.

17. The groove portion is such that the distance between the surfaces constituting the wall portion is It decreases from the radially inner side to the radially outer side. The rod-shaped body dispensing mechanism according to claim 11.

18. The groove portion has the same depth at least at the axial front end and the axial rear end. The rod-shaped body dispensing mechanism according to claim 11.

19. The depth of the bottom surface of the groove differs in the front-to-back direction of the chuck. The rod-shaped body dispensing mechanism according to claim 11.

20. The bottom surface of the groove is deeper in the forward direction of the chuck. The rod-shaped body dispensing mechanism according to claim 19.

21. The bottom surface of the groove is deeper in the rear direction of the chuck. The rod-shaped body dispensing mechanism according to claim 19.

22. The difference in depth of the bottom surface of the groove is 0.1 mm or more and 0.7 mm or less. The rod-shaped body dispensing mechanism according to claim 19.

23. The connecting portion of the groove has a stepped portion in the axial direction. The rod-shaped body dispensing mechanism according to claim 19.

24. The connection portion of the groove is a single plane. The rod-shaped body dispensing mechanism according to claim 11.

25. The angle between the plane of the connection portion of the groove and the plane passing through the central axis and perpendicular to the depth direction of the groove is 10° or more and 45° or less. The rod-shaped body dispensing mechanism according to claim 24.

26. The connection portion of the groove is curved in the axial direction. The rod-shaped body dispensing mechanism according to claim 11.

27. The connection portion of the groove is concave. The rod-shaped body dispensing mechanism according to claim 26.

28. The connection portion of the groove is convex. The rod-shaped body dispensing mechanism according to claim 26.

29. The radius of curvature of the curved surface of the connection portion of the groove is R1 (1 mm) or more and R20 (20 mm) or less. The rod-shaped body dispensing mechanism according to claim 26.

30. The connection portion of the groove is curved in cross-section along the axial direction. The rod-shaped body dispensing mechanism according to claim 26.

31. The connection portion of the groove is curved in cross-section along the radial direction. The rod-shaped body dispensing mechanism according to claim 11.

32. The number of grooves is the same as the number of divisions in front of the chuck. A rod-shaped body dispensing mechanism according to any one of claims 2 to 5.

33. The number of grooves is greater than the number of divisions in front of the chuck. A rod-shaped body dispensing mechanism according to any one of claims 2 to 5.

34. When there are multiple grooves, the grooves are positioned point-symmetrically to each other. The rod-shaped body dispensing mechanism according to claim 1.

35. When there are multiple grooves, the grooves are positioned symmetrically to each other. The rod-shaped body dispensing mechanism according to claim 1.

36. When there are multiple grooves, the arc lengths of the circumferences between the grooves are different from each other. The rod-shaped body dispensing mechanism according to claim 1.

37. When there are multiple grooves, the dimensions of the edges constituting the grooves differ at least one point. The rod-shaped body dispensing mechanism according to claim 1.

38. The distance between the surfaces that make up the wall portion of the groove is, Smaller than the minimum diameter of any cross-section of the rod-shaped body, The rod-shaped body dispensing mechanism according to claim 1.

39. It consists of at least a cylindrical body, a chuck, and a spring. The cylindrical body is positioned radially outward from the chuck. The zipper has a hole that runs through from the front end to the back end on the inside. The front is divided into at least two or more sections. Inside the front divided section, there is a gripping section that has the function of gripping and releasing a rod-shaped object. It is positioned to be able to move back and forth relative to the cylindrical body. The spring biases the chuck backward. On the plane perpendicular to the central axis of the hole inside the chuck, A groove is formed that is closed on the radially outer side. The groove extends through in the axial direction. The number of grooves is less than the number of divisions in front of the chuck. A mechanism for extending a rod-shaped object.

40. It consists of at least a cylindrical body, a chuck, and a spring. The cylindrical body is positioned radially outward from the chuck. The zipper has a hole that runs through from the front end to the back end on the inside. The front is divided into at least two or more sections. Inside the front divided section, there is a gripping section that has the function of gripping and releasing a rod-shaped object. It is positioned to be able to move back and forth relative to the cylindrical body. The spring biases the chuck backward. On the plane perpendicular to the central axis of the hole inside the chuck, A groove is formed that opens radially outward. The groove is closed in one direction, either axially or otherwise. The number of grooves is less than the number of divisions in front of the chuck. A mechanism for extending a rod-shaped object.

41. It consists of at least a cylindrical body, a chuck, and a spring. The cylindrical body is positioned radially outward from the chuck. The zipper has a hole that runs through from the front end to the back end on the inside. The front is divided into at least two or more sections. Inside the front divided section, there is a gripping section that has the function of gripping and releasing a rod-shaped object. It is positioned to be able to move back and forth relative to the cylindrical body. The spring biases the chuck backward. On the plane perpendicular to the central axis of the hole inside the chuck, A groove is formed that is closed on the radially outer side. The groove is closed in one direction, either axially or otherwise. The number of grooves is less than the number of divisions in front of the chuck. A mechanism for extending a rod-shaped object.

42. The barrel and, A tip member positioned at the front end of the shaft cylinder, A chuck set, which is a rod-shaped body feeding mechanism, is positioned inside the shaft cylinder and comprises at least the cylindrical body, the chuck, and the spring. The mechanism for extending the rod-shaped body, which is a chuck set, is at least composed of an operating body that can press the chuck set from its rear end, The operating body is positioned so that the cylindrical body or the chuck can be advanced by pressing, A mechanical pencil equipped with a chuck set which is a rod-shaped body extension mechanism according to claim 1, or any one of claims 39 to 41.

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