JP5241464B2 - mechanical pencil - Google Patents

Description

  The present invention relates to a rear end knock type mechanical pencil capable of simplifying an assembling operation.

  As is well known, the rear end knock type mechanical pencil is operated by knocking a knock portion disposed at the rear end portion, for example, a knock cover, so that the core tank in the shaft cylinder receives the shaft, and the shaft is passed through the core tank. The chuck is configured to push out a chuck that holds a writing core disposed in front of the cylinder.

  When the chuck is pushed forward, the chuck projects from the tightening ring and opens, and the return spring acts by stopping the knocking operation so that the chuck is accommodated in the tightening ring and is reduced in diameter. That is, the chuck acts to sequentially feed the writing core forward by releasing and gripping the writing core by repeating the knocking operation.

  By the way, in the mechanical pencil described above, the writing core becomes unevenly worn as the writing progresses, so that the phenomenon that the drawn line becomes thicker than that at the beginning of writing occurs, and not only the thickness of the drawn line changes, but also the writing Since the contact area of the writing core with respect to the surface also changes, there is a problem that the darkness of the drawn line changes as the writing progresses. In order to solve such a problem, the present applicant has proposed a mechanical pencil that can rotate the writing core (replacement core) using the writing pressure. For example, Japanese Patent Application No. 2007-278904-278905 has filed an application. doing.

  According to this configuration, the chuck is held in the shaft cylinder so as to be rotatable around the lead tank while holding the writing lead, and is rotated through the chuck by the writing pressure of the writing lead. A rotation drive mechanism is provided for rotating the writing core by rotating the rotor by the backward and forward movements of the child.

  In the mechanical pencil having the above-described writing core rotation driving mechanism, in the configuration in which the knock cover (knock portion) is attached to the rear end portion of the core case, the knock cover also rotates together with the rotation operation of the writing core. Therefore, for example, when the user unconsciously rotates the knock cover with a fingertip or the like, this is transmitted to the rotation drive mechanism, which causes a problem that the rotation drive mechanism is impaired.

  In addition, when the knock cover is inadvertently touching something, or when writing is performed while the knock cover is intentionally grasped, the function of the rotational drive mechanism is stopped. Depending on this, it may cause a failure of the rotary drive mechanism.

  Therefore, in the above-mentioned previous application, in order to solve such a problem, the knocking operation of the knock cover can be transmitted to the lead tank side, and the rotation operation on the lead tank side is transferred to the knock cover side. Proposes a configuration in which a separation portion that is not transmitted is formed.

  As described above, according to the configuration in which the knock cover in which the knock operation is performed and the lead tank are mechanically separated, the knock cylinder supporting the knock cover and the bias cylinder are urged in the retreating direction. For example, a spring member (return spring) formed in a coil shape may come out of the rear end side of the shaft tube and fall off, and special measures are required to suppress this.

Patent Document 1 discloses a mechanical pencil having a structure in which a knock cover and a lead tank are mechanically separated from each other, although not provided with the above-described writing lead rotation driving mechanism.
JP-A-8-156483

  By the way, according to the configuration disclosed in the above-mentioned patent document, a knock cylinder that slides in the shaft cylinder is provided integrally with a knock cover in which a knock operation is performed, and the knock cylinder is moved backward in front of the knock cylinder. A coiled return spring that biases in the direction is housed. And the structure which formed the latching | locking part in the side wall of a knock cylinder is shown so that the said knock cylinder and a coil-shaped return spring may come out from the rear-end part side of a shaft cylinder, and may not fall.

  That is, the locking portion is constituted by an elastic piece raised on the side wall of the knock cylinder and a window hole formed at the rear end of the shaft cylinder. Then, the elastic piece is deformed by pushing the knock cylinder into the shaft cylinder, and enters the window hole formed in the shaft cylinder from the inside of the shaft cylinder, so that the knock cylinder does not fall out of the shaft cylinder. Has been.

  According to the configuration described above, a window hole is formed in the vicinity of the rear end portion of the shaft tube, and the configuration in which the elastic piece slides in the window hole is visually recognized as it is. It causes problems such as poor appearance and lack of luxury.

  The present invention proposes a knock cylinder that slides in the shaft cylinder, and an attachment mechanism that prevents the return spring and the like of the knock cylinder from falling off the shaft cylinder. It is an object of the present invention to provide a rear-end knock-type mechanical pencil that can simplify the assembly work without influencing.

  The mechanical pencil according to the present invention, which has been made to solve the above-described problems, advances the chuck provided at the front end portion of the core tank by knocking the knock portion disposed at the rear end portion of the shaft cylinder. The pencil is configured to be able to feed the writing core forward, and is formed integrally with or separately from the knock portion, and slides in the shaft cylinder by a knock operation of the knock portion, A knock cylinder formed by protruding at least one convex member along the axial direction of the outer peripheral surface, and an inner peripheral surface of the shaft cylinder on which the knock cylinder slides are formed so as to protrude in parallel along the axial direction. The first and second ribs formed on the rear end of the pair of ribs and a connecting rib projectingly formed so as to connect the two at the rear end side of the pair of ribs, and the first and second ribs. rib Locking projections formed so that the lengths of the front end sides are different from each other are provided, and the convex member in the knock cylinder projects into the shaft cylinder by the action of a return spring that pushes the knock cylinder backward. The knock cylinder is held by the shaft cylinder by reciprocatingly moving in the U-shaped space of the locking protrusion.

  In this case, preferably, the shaft cylinder is constituted by a front shaft and a rear shaft, the chuck and the core tank are mounted in the front shaft, the locking projection is provided in the rear shaft, and the knock cylinder is mounted. Configured. Preferably, the knock cylinder and the lead tank are separated from each other.

  A large-diameter portion is formed on the rear end side of the knock tube, the large-diameter portion being in axial contact with a connecting rib of a locking projection formed on the inner peripheral surface of the shaft tube, and the large-diameter portion and the convex member And the length of the front end side of the first and second ribs of the locking projection formed on the inner peripheral surface of the shaft cylinder is b and c, respectively, b <a < It is desirable that the dimensional relationship is c.

  Further, in a preferred embodiment, the convex member is formed on the outer peripheral surface of the knock cylinder so as to protrude at equal intervals along the circumferential direction, and the same number as the convex member is provided in the shaft cylinder. The locking projections are independently formed at equal intervals along the inner circumferential direction, and the circumferential spacing of the locking projections formed in the shaft cylinder is the width of the convex member formed on the knock cylinder. The configuration is larger.

  Further, preferably, the convex member formed on the outer peripheral surface of the knock cylinder is formed so as to protrude in the axial direction from the front end portion of the knock cylinder, and the protruding portion forward in the axial direction of the convex member is It is configured to receive an outer diameter portion of the return spring formed in a coil shape in contact with the front end portion of the knock cylinder.

  In the above-described configuration, the chuck is held in the shaft cylinder so as to be rotatable with the core tank as an axis while the chuck holds the writing core, and the chuck by the writing pressure of the writing core is used. A mechanical pencil that is configured to transmit a rotational movement of the rotor to the writing core via the chuck, the rotary driving mechanism rotating the rotor by retreating and moving forward through the rotor It can employ | adopt suitably.

  According to the mechanical pencil having the above-described configuration, the first and second ribs and the connecting ribs in the shaft cylinder are formed with U-shaped protruding protrusions, and the protrusions formed on the outer peripheral surface of the knock cylinder. Since the cylindrical member is configured to be accommodated in the U-shaped space of the locking projection, the knock cylinder can be securely attached to the rear end portion of the shaft cylinder.

  In addition, since the first and second ribs are formed to have different lengths leading to the front side of the shaft tube, the knock tube is inserted from the rear end portion of the shaft tube, and the knock tube is moved one by one. By rotating in the direction, the convex member formed in the knock cylinder can be easily accommodated in the U-shaped space of the locking projection formed in the shaft cylinder.

  In this case, the shaft cylinder is constituted by a front shaft and a rear shaft, the chuck and the core tank are mounted in the front shaft, the locking projection is provided in the rear shaft, and the knock cylinder is mounted. In the assembling process of mounting the knock cylinder in the rear shaft, the rear shaft is moved to the core by loosening, for example, a screw between the front shaft and the rear shaft. It can be moved backward relative to the tank.

  Therefore, when the knock cylinder is mounted in the rear shaft from its rear end, the knock cylinder collides with the rear end of the core tank and the knock cylinder is prevented from moving forward, thereby causing a problem in mounting the knock cylinder. Can be resolved.

  According to the above-described configuration, it is possible to easily and simplify the assembling work of the mechanical pencil, and it is possible to form a mechanism in the shaft tube that prevents the knock tube from dropping off from the shaft tube. Therefore, as disclosed in Patent Document 1, it is possible to eliminate the problem that the knock cylinder drop-off prevention mechanism impairs the appearance and causes a problem of lack of luxury.

  Hereinafter, a mechanical pencil according to the present invention will be described based on an embodiment shown in the drawings. The embodiment described below shows an example in which the present invention is applied to a mechanical pencil capable of rotating a writing core (replacement core) using writing pressure. The writing core rotation drive mechanism will be described.

  FIG. 1 and FIG. 2 are sectional views showing a front half and a rear half of a mechanical pencil according to the present invention. First, reference numeral 1A shown in FIG. 1 indicates a shaft cylinder (hereinafter also referred to as a front shaft) that constitutes the outline thereof, and reference numeral 2 indicates a lower cam forming member, which will be described later, on the tip side of the shaft cylinder 1A. The tip part attached via is shown.

  A cylindrical core case 3 is coaxially accommodated in the shaft cylinder 1 </ b> A, and a chuck 4 is connected to the tip of the core case 3. The chuck 4 has a through hole 4a formed along its axis, and the tip portion is divided into a plurality of pieces so that the divided tip portion is loosely fitted in a fastener 5 formed in a ring shape. It is installed. The ring-shaped fastener 5 is attached to the inner surface of the tip of the rotor 6 formed in a cylindrical shape so as to cover the periphery of the chuck 4.

  A tip pipe 7 is provided so as to protrude from the tip portion 2, and the base end portion of the tip pipe 7 is fitted to the inner surface of the tip portion of the support member 8 located in the tip portion 2. The support member 8 is formed in a stepped shape in which a cylindrical portion is continuous so that the base end portion (rear end portion) side has a large diameter, and the inner surface of the base end portion is the tip of the rotor 6 described above. It is fitted to the peripheral side. A rubber holding chuck 9 having a through hole 9 a formed in the shaft core portion is accommodated on the circumferential surface of the support member 8 that supports the tip pipe 7.

  With the configuration described above, a straight core insertion hole reaching the tip pipe 7 through the through hole 4 a formed in the chuck 4 from the core case 3 and the through hole 9 a formed in the shaft core of the holding chuck 9. A writing core (replacement core) (not shown) is inserted into the linear core insertion hole. A coiled return spring 10 is disposed in the space between the rotor 6 and the chuck 4 described above.

  One end (rear end) of the return spring 10 is in contact with the end surface of the core case 3, and the other end (front end) of the return spring 10 is in contact with an annular end surface formed in the rotor 6. It is housed in the state. Therefore, the chuck 4 in the rotor 6 is urged in the retracting direction by the action of the return spring 10.

  In the mechanical pencil shown in the figure, the core case 3 moves forward in the shaft cylinder 1A by knocking a knock section (described later) disposed at the rear end portion of the shaft cylinder (rear shaft), and the tip of the chuck 4 is moved forward. The gripping state of the writing core is released when the portion protrudes from the fastener 5. When the knocking operation is released, the lead case 3 and the chuck 4 are retracted in the shaft cylinder 1A by the action of the return spring 10.

  At this time, the writing core is held in a through hole 9 a formed in the holding chuck 9. In this state, the chuck 4 retreats and the tip portion is accommodated in the fastener 5 so that the writing core is again held. That is, the writing core is released and gripped by the back and forth movement of the chuck 4 by repeating the knocking operation of the knocking portion, and the writing core acts so as to be sequentially advanced forward from the chuck 4.

  The rotor 6 shown in FIG. 1 is formed in an annular shape whose central portion in the axial direction has a large diameter, and a first cam surface 6a is formed on one end surface (rear end surface) formed in an annular shape. A second cam surface 6b is formed on the other end surface (front end surface) formed in an annular shape. On the other hand, a cylindrical upper cam forming member 13 is attached to the rear end portion of the rotor 6 in the shaft cylinder 1A so as to cover the rear end portion of the rotor 6, and the upper cam forming member 13 A fixed cam surface (also referred to as a first fixed cam surface) 13 a is formed at the front end of the rotor 6 so as to face the first cam surface 6 a of the rotor 6.

  Further, a cylindrical lower cam forming member 14 is attached to the shaft cylinder 1A so as to cover the rotor 6, and is opposed to the second cam surface 6b of the rotor 6 at a substantially central portion thereof. Thus, a fixed cam surface (also referred to as a second fixed cam surface) 14a is formed. The relationship between the first and second cam surfaces 6a, 6b formed on the rotor 6, the first fixed cam surface 13a, and the second fixed cam surface 14a and their mutual actions are as follows. This will be described in detail later with reference to FIGS.

  Further, as shown in FIG. 1, a cylindrical stopper 16 is fitted on the inner surface of the rear end of the upper cam forming member 13 formed in a cylindrical shape, and the front end of the stopper 16 and the cylindrical shape are formed in a cylindrical shape. A coiled spring member 18 is mounted between the torque canceller 17 that is formed and movable in the axial direction.

  The spring member 18 acts to urge the torque canceller 17 forward, and the rotor 6 is configured to be pushed forward by being pushed by the torque canceller 17 receiving the urging force.

  According to the above-described configuration, the rotor 6 is rotatable with the chuck 4 and the core tank 3 as the shaft core in a state where the chuck 4 grips the writing core. When the mechanical pencil is not used (in a case other than the writing state), the rotor 6 is biased forward via the torque canceller 17 by the action of the spring member 18, and the state shown in FIG. To be made.

  On the other hand, when a mechanical pencil is used, that is, when a writing pressure is applied to a writing core (not shown) protruding from the tip pipe 7, the chuck 4 moves backward against the urging force of the spring member 18. Accordingly, the rotor 6 also moves backward in the axial direction. Therefore, the first cam surface 6a formed on the rotor 6 is brought into mesh with the first fixed cam surface 13a.

  FIGS. 3A to 3C and FIGS. 4D and 4E explain the basic operation of the rotation driving mechanism for rotating the rotor 6 by the above-described operation step by step. 3 and 4, reference numeral 6 schematically shows the above-described rotor, and one end face (the upper face in the figure) is continuously serrated along the circumferential direction. The first cam surface 6a is formed in an annular shape. Similarly, a second cam surface 6b that is continuously serrated along the circumferential direction is formed in an annular shape on the other end surface of the rotor 6 (the lower surface in the figure).

  On the other hand, as shown in FIGS. 3 and 4, the first fixed cam surface 13 a that is continuously serrated along the circumferential direction is also formed on the annular end surface of the upper cam forming member 13. A second fixed cam surface 14 a that is continuously serrated along the circumferential direction is also formed on the annular end surface of the lower cam forming member 14. The first cam surface 6 a, the second cam surface 6 b formed on the rotor 6, the first fixed cam surface 13 a formed on the upper cam forming member 13, and the first cam surface formed on the lower cam forming member 14. The cam surfaces formed in a sawtooth shape along the circumferential direction on the two fixed cam surfaces 14a are formed so that their pitches are substantially the same.

  FIG. 3A shows the relationship among the upper cam forming member 13, the rotor 6, and the lower cam forming member 14 when the mechanical pencil is not used (in a case other than the writing state). In this state, the second cam surface 6b formed on the rotor 6 is located on the second fixed cam surface 14a side of the lower cam forming member 14 attached to the shaft cylinder 1A, and the spring member 18 shown in FIG. It is contacted by the urging force. At this time, the first cam surface 6a on the rotor 6 side and the first fixed cam surface 13a are set so as to have a half-phase (half-pitch) offset with respect to one tooth of the cam in the axial direction. ing.

  FIG. 3B shows an initial state in which writing pressure is applied to the writing core by using a mechanical pencil. In this case, as described above, the rotor 6 moves with the spring 4 as the chuck 4 moves backward. The member 18 is contracted and retracted in the axial direction. Thereby, the rotor 6 moves to the upper cam forming member 13 attached to the shaft cylinder 1A.

  FIG. 3C shows a state where the writing pressure is applied to the writing core by using the mechanical pencil, and the rotor 6 is in contact with the upper cam forming member 13 and retracted. In this case, the rotor 6 The formed first cam surface 6a meshes with the first fixed cam surface 13a on the upper cam forming member 13 side. Thereby, the rotor 6 receives a rotational drive corresponding to a half phase (half pitch) of one tooth of the first cam surface 6a.

  3 and 4, the circles drawn at the center of the rotor 6 indicate the rotational movement amount of the rotor 6. In the state shown in FIG. 3C, the second cam surface 6b on the rotor 6 side and the second fixed cam surface 14a are half phase (half pitch) with respect to one tooth of the cam in the axial direction. It is set to be in a shifted relationship.

  Next, FIG. 4D shows an initial state where writing with the mechanical pencil is finished and the writing pressure with respect to the writing core is released. In this case, the rotor 6 is moved by the action of the spring member 18 described above. Advance in the axial direction. Thereby, the rotor 6 moves to the lower cam forming member 14 attached to the shaft cylinder 1A.

  Further, FIG. 4E shows a state in which the rotor 6 has advanced by contacting the lower cam forming member 14 by the action of the spring member 18 described above. In this case, the rotor 6 is formed on the rotor 6. The second cam surface 6b meshes with the second fixed cam surface 14a on the lower cam forming member 14 side. As a result, the rotor 6 is again subjected to rotational driving corresponding to a half phase (half pitch) of one tooth of the second cam surface 6b.

  Therefore, as indicated by a circle drawn at the center of the rotor 6, the rotor 6 receives the first and second cam surfaces 6 a, 6b is rotated corresponding to one tooth (one pitch), and the writing core gripped by the chuck 4 is also rotated in the same manner.

  According to the mechanical pencil having the above-described configuration, the rotor receives a rotational motion corresponding to one tooth of the cam each time by reciprocation of the rotor 6 in the axial direction by writing, and the writing core is sequentially rotated by this repetition. The Therefore, it is possible to prevent the writing core from being unevenly worn as the writing progresses, and it is possible to solve the problem that the thickness of the drawn line and the darkness of the drawn line change greatly.

  Further, according to the mechanical pencil having the above-described configuration, the tip pipe 7 that guides the writing core that protrudes from the tip 2 is fitted to the tip of the rotor 6 via the support member 8. The tip pipe 7 moves in the same direction via the support member 8 as the chuck 4 moves backward and forward along with the writing operation. Therefore, even if the writing action causes a cushioning action in which the writing core moves backward and forward, the tip pipe that guides the writing core also moves in the same direction. The movement does not occur, and the protruding dimension of the writing core from the tip pipe can be kept constant.

  Further, since the tip pipe 7 is coupled to the rotor 6 via the support member 8, when the writing core is subjected to a rotational motion, the tip pipe is similarly subjected to the rotational motion. The writing core will rotate as a unit.

  Accordingly, it is possible to solve the problem that the writing dimension of the writing core from the tip pipe changes each time during writing and gives the user a sense of discomfort. Furthermore, it is possible to prevent the occurrence of core breakage due to cutting of the core in the tip pipe due to the change in the writing core protruding dimension from the tip pipe, and to eliminate the problem of contaminating the writing surface by scraping the core. Can do.

  The cylindrical torque canceller 17 that pushes the rotor 6 forward by receiving the biasing force of the coiled spring member 18 is between the front end face of the torque canceller 17 and the rear end face of the rotor 6. By causing slippage, the rotor 6 is prevented from being transmitted to the spring member 18 due to the repetitive writing action.

  In other words, the torque canceller 17 formed in a cylindrical shape is interposed between the rotor 6 and the spring member 18 to prevent the rotational motion of the rotor from being transmitted to the spring member. Thus, the problem that the rotating operation of the rotor 6 is obstructed can be solved by causing the spring member 18 to twist back (spring torque).

  As shown in FIG. 1, a cylindrical metal connecting member 20 is attached to the rear end portion of the front shaft 1A by being screwed onto the inner peripheral surface of the rear end portion of the front shaft 1A. The inner peripheral surface of the shaft cylinder 1B (hereinafter also referred to as a rear shaft) is fitted to the connecting member 20, whereby the shaft cylinder 1A constituting the front shaft and the shaft cylinder 1B constituting the rear shaft. Are connected in a straight line. The fitting of the rear shaft 1B to the connecting member 20 is a strong fitting that cannot be removed by the user. Or you may use an adhesive together for a fitting part.

  As shown in FIG. 2, for example, a metal clip 21 is attached to the rear end portion of the shaft tube 1 </ b> B, and a cylinder is provided between the shaft tube 1 </ b> B and the core case 3 on the rear end side of the shaft tube 1 </ b> B. A knock cylinder 22 formed in a shape is accommodated. The knock cylinder 22 receives a biasing force so as to be pushed backward by a coiled return spring 23 disposed between a front end portion of the knock cylinder 22 and a flange formed in the connection member 20. ing.

  The knock cylinder 22 is slidable in the axial direction in the rear end portion of the shaft cylinder 1B and does not come out of the rear end portion of the shaft cylinder 1B, that is, in a non-knock state, as shown in FIG. It is attached in the shaft cylinder 1B so that it becomes. The specific mounting structure will be described in detail later.

  A partition 22b having a writing core replenishment port 22a is formed slightly behind the axial intermediate portion of the knock cylinder 22, and the rear of the partition 22b constitutes an accommodation space for the eraser 24. doing. A knock cover ring 27 to which the knock cover 26 is attached is detachably attached to the rear end portion of the knock cylinder 22, and the eraser 24 is covered by the knock cover 26 and the knock cover ring 27.

  In addition, as shown in FIG. 2, the partition wall 22 b formed in the knock cylinder 22 is configured to face the rear end portion of the core tank 3 with a slight gap G. The knock portion including the cylinder 22 and the core tank 3 are separated from each other. The gap G is preferably set at an interval that does not interfere with the backward movement of the rotor 6 through the chuck due to the writing pressure of the writing core.

  According to this configuration, even when the chuck 4 and the lead case 3 are retracted by writing, the rear end portion of the lead case 3 does not collide with the partition wall constituting the replenishing port 27, thereby rotating the writing lead as described above. The normal rotational drive operation of the mechanism can be guaranteed.

  When the knock cover 26 is knocked, the partition wall 22b hits the rear end portion of the lead tank 3 through the knock cylinder 22 and acts to push the lead tank 3 forward as it is. As a result, the chuck 4 moves forward as described above and acts so that the writing core is fed out from the tip pipe 7. Further, when the knocking operation is released, the knock cylinder 22 is moved back to the state shown in FIG.

  FIG. 5 illustrates a mounting structure of the knock cylinder 22 that is slidably held in the shaft cylinder 1B. Convex members 30 are formed on the outer peripheral surface of the knock cylinder 22 at equal intervals along the circumferential direction. In this embodiment, the convex members 30 are formed in a straight line on the front end side (the left end portion side in FIG. 5) of the knock cylinder 22 at regular intervals of approximately 90 degrees in the circumferential direction. Further, a part of the convex member 30 slightly protrudes in the axial direction from the front end portion of the knock cylinder 22 to form a protruding portion 30a.

  On the rear end side of the knock cylinder 22, a large-diameter portion 31 is formed in an annular shape so as to surround the knock cylinder 22. The large-diameter portion 31 is dimensioned so that it can abut on a connecting rib of a locking projection formed on the inner peripheral surface of a shaft cylinder 1B, which will be described later. In this embodiment, the distance between the large-diameter portion 31 and the convex member 30 is defined as a for convenience as shown in FIG.

  Further, a groove 32 cut in the axial direction is formed at the rear end of the knock cylinder 22. As will be described later, when the knock cylinder 22 is inserted and incorporated into the shaft cylinder 1B as indicated by an arrow in FIG. 5, the groove section 32 uses a jig such as a flat-blade screwdriver (not shown). It is used when rotating in the circumferential direction.

  On the other hand, a locking projection 35 protruding in a U shape is formed on the inner peripheral surface of the shaft tube 1B. The locking projection 35 is formed by a first rib 35a and a second rib 35b that are formed to protrude in parallel along the axial direction, and a connecting rib 35c that connects the two at the rear end side of the pair of ribs. Is formed. The lengths on the front end sides of the first and second ribs 35a and 35b are set differently, that is, set to the lengths indicated by b and c in FIG.

  The locking projections 35 having the above-described configuration are independently formed at equal intervals of approximately 90 degrees along the inner circumferential direction of the shaft cylinder 1B. As shown in FIG. 5, the circumferential distance d of the locking projection 35 formed in the shaft cylinder 1 </ b> B is larger than the width e of the convex member 30 formed in the knock cylinder 22. Yes.

  In order to attach and hold the knock cylinder 22 in the shaft cylinder 1B, a screw between the front shaft 1A shown in FIGS. 1 and 2 and the connecting member 20 coupled to the rear shaft 1B is used. The rear shaft 1B is moved backward relative to the core tank 3 by loosening. Thus, as will be described later, when the knock cylinder is mounted in the rear shaft from its rear end, the partition wall 22b formed in the knock cylinder 22 collides with the rear end of the core tank 3 and knock cylinder. Can be prevented, and the problem of causing trouble in the mounting of the knock cylinder 22 can be solved.

  As described above, in the state where the screw between the front shaft 1A and the connecting member 20 coupled to the rear shaft 1B is loosened, the return spring 23 is inserted first from the rear end portion of the rear shaft 1B. . Subsequently, as shown in FIG. 5, the knock cylinder 22 is inserted from the rear end of the rear shaft 1B.

  In this case, an operation of rotating the knock cylinder 22 while lightly pushing the knock cylinder 22 into the shaft cylinder 1B by applying a tip of a not-shown flathead screwdriver or the like to the groove 32 formed at the rear end of the knock cylinder 22 By doing so, the protruding portion 30a slightly protruding from the front end portion of the knock cylinder 22 acts so as to enter between the locking projections 35 formed in the shaft cylinder 1A. That is, the protrusion 30a effectively functions as a guide for inserting the convex member 30 formed in the knock cylinder 22 between the locking protrusions 35 (in the interval d).

  FIG. 6 is a schematic diagram for explaining the mounting order of the knock cylinder 22 in the shaft cylinder 1B thereafter. In FIG. 6, the two locking projections 35 formed in the shaft cylinder 1 </ b> B are developed in a planar shape, and the two convex members 30 formed on the outer peripheral surface of the knock cylinder 22 are similarly planarized. Shown in an expanded state.

  That is, as shown in FIG. 6A, the protrusion 30a in the convex member 30 functions as a guide as described above, so that the convex member 30 is placed between the locking projections 35 (interval d). Easy to guide. Since the dimensions d and e shown in FIG. 6A are d> e as described above, the knock cylinder 22 can be easily inserted into the shaft cylinder 1B.

  In this state, when the knock cylinder 22 is advanced in the shaft cylinder 1B while pressing and retracting the return spring 23 previously inserted into the shaft cylinder 1B, the large-diameter portion 31 formed in the knock cylinder 22 becomes the shaft cylinder. It abuts on the connecting rib 35c of the locking projection 35 that protrudes from 1B. FIG. 6B shows the positional relationship between the convex member 30 and the locking projection 35 in this state.

  That is, as described above, the distance between the large-diameter portion 31 and the convex member 30 in the knock cylinder 22 is a, and the length of the front end side of the first and second ribs 35a and 35b formed in the shaft cylinder 1B. Where b and c are respectively, the relation of b <a <c is established. Accordingly, the rear end portion of the convex member 30 at this time is located between the front end portion of the first rib 35a and the front end portion of the second rib 35b.

  Therefore, by rotating the knock cylinder 22 counterclockwise in this state, the convex member 30 can be brought into contact with the second rib 35b from the side surface. Therefore, by releasing the pushing operation of the knock cylinder 22 in the state as it is, the convex spring 30 is moved into the U-shaped space of the locking projection 35 by the action of the return spring 23 as shown in FIG. Can be accommodated. As a result, as shown in FIG. 6C, the knock cylinder 22 is held in the axial cylinder 1B in a slidable state in the axial direction (in the knock direction).

  After the knock cylinder 22 is accommodated in the shaft cylinder 1B by the above-described operation, the screw between the front shaft 1A and the connecting member 20 coupled to the rear shaft 1B is tightened. A mechanical pencil is completed by attaching the eraser 24 shown in FIG. 2 and a knock cover 26 functioning as a knock portion to the rear end portion.

  FIG. 7 shows a preferable relationship between the knock cylinder 22 and the return spring 23. In FIG. 7, the knock cylinder 22 is shown in a sectional view. As already described, the knock cylinder 22 is brought into contact with the return spring 23 formed in a coil shape at the front end portion thereof, and acts to return the knock cylinder 22 to its original state by releasing the knock operation.

  In this case, the protruding portion 30 a formed to protrude in the axial direction from the front end portion of the knock cylinder 22 is configured to receive the outer diameter portion of the coiled return spring 23 that contacts the front end portion of the knock cylinder 22. It is desirable. That is, as shown in FIG. 7, the protrusion 30a receives the end of the return spring 23 so as to bend and bend, so that the return spring 23 can be accommodated concentrically with the shaft core, and the spring collapses during assembly. It is possible to avoid the problem that (deviation) occurs.

  According to the mechanical pencil according to the present invention described above, the protruding member 30 is formed so as to protrude along the axial direction of the knock cylinder 22, and the length of both legs is within the shaft cylinder 1B in which the knock cylinder 22 is accommodated. Since the different U-shaped locking projections 35 are formed so as to protrude, the coiled return spring 23 and the knock cylinder 22 are sequentially inserted from the rear end portion of the shaft cylinder 1B so that the knock cylinder 22 is slidably mounted. be able to. From this, the effect as described in the column of the effect of above-mentioned invention can be obtained.

  In the embodiment described above, the four protruding members 30 are arranged in the knock cylinder 22 and the same number of locking projections 35 are arranged in the shaft cylinder 1B. It can be set arbitrarily. Moreover, although this invention can be suitably employ | adopted as a mechanical pencil in which a writing lead is rotated with a chuck | zipper and a lead tank with writing like embodiment, it shows in above-mentioned patent document 1 in which a writing lead is not rotated. It can also be applied to such mechanical pencils. Furthermore, in the embodiment, the knock cylinder 22 described above is formed separately from the knock cover 26 that functions as a knock portion, but it may be formed integrally.

It is sectional drawing which showed the front half part in embodiment of this invention. It is sectional drawing which showed the latter half part similarly. FIG. 3 is a schematic diagram for explaining step by step the rotational driving action of a rotor mounted on the embodiment shown in FIGS. FIG. 4 is a schematic diagram for explaining the rotational driving action of the rotor following FIG. 3. It is a partial sectional view explaining the relation between a shaft cylinder and a knock cylinder. It is a schematic diagram explaining the mounting | wearing order of the knock cylinder in a shaft cylinder. It is sectional drawing explaining the relationship between a knock cylinder and a return spring.

Explanation of symbols

1A Shaft cylinder (front shaft)
1B Shaft cylinder (rear shaft)
2 mouth end portion 3 core case 4 chuck 5 fastener 6 rotor 7 tip pipe 10 return spring 20 connecting member 22 knock cylinder 22a writing core replenishment port 22b partition wall 23 return spring 24 eraser 26 knock cover 30 convex member 30a protruding portion 35 Locking protrusion 35a 1st rib 35b 2nd rib 35c Connection rib G Gap (separation part)

Claims (7)

With a mechanical pencil that is configured to advance the chuck provided at the front end of the lead tank and feed the writing lead forward by knocking the knock part located at the rear end of the barrel. There,
The knock part is formed integrally with or separately from the knock part, and slides in the shaft cylinder by a knocking operation of the knock part, and at least one convex member protrudes along the axial direction of the outer peripheral surface thereof. A knock cylinder,
On the inner peripheral surface of the shaft cylinder on which the knock cylinder slides, the first and second ribs formed so as to protrude in parallel along the axial direction and the rear ends of the pair of ribs are connected to each other. A locking protrusion formed in a U shape by the protruding connecting rib and having different lengths on the front end sides of the first and second ribs,
Due to the action of a return spring that pushes the knock cylinder rearward, the convex member of the knock cylinder reciprocates in the U-shaped space of the locking projection formed in the shaft cylinder, so that the knock cylinder Is held by the shaft cylinder.   The shaft cylinder is constituted by a front shaft and a rear shaft, the chuck and the core tank are mounted in the front shaft, the locking projection is provided in the rear shaft, and the knock cylinder is mounted. The mechanical pencil according to claim 1.   The mechanical pencil according to claim 1 or 2, wherein the knock cylinder and the lead tank are separated from each other.   A large-diameter portion is formed on the rear end side of the knock tube, the large-diameter portion being in axial contact with a connecting rib of a locking protrusion formed on the inner peripheral surface of the shaft tube, and the large-diameter portion and the convex member When the distance between them is a, and the lengths of the front end sides of the first and second ribs in the locking projections formed on the inner peripheral surface of the shaft cylinder are b and c, respectively, b <a <c The mechanical pencil according to any one of claims 1 to 3, wherein the mechanical pencil is in a dimensional relationship.   The convex member is formed on the outer peripheral surface of the knock cylinder so as to protrude at equal intervals along the circumferential direction, and the same number of the locking projections as the convex member are provided in the inner peripheral direction in the shaft cylinder. Are formed independently at equal intervals along the circumferential direction of the locking projections formed in the shaft cylinder, and are formed larger than the width of the convex member formed in the knock cylinder. The mechanical pencil according to any one of claims 1 to 4.   The convex member formed on the outer peripheral surface of the knock cylinder is formed so as to protrude in the axial direction from the front end portion of the knock cylinder, and the protruding portion forward in the axial direction of the convex member is the front end of the knock cylinder. The mechanical pencil according to claim 5, wherein the mechanical pencil is configured to receive an outer diameter portion of the return spring formed in a coil shape in contact with the portion.   While the chuck holds the writing core, the chuck is held in the shaft cylinder so as to be rotatable about the core tank, and the rotor through the chuck is driven by the writing pressure of the writing core. The rotary drive mechanism that rotationally drives the rotor by a backward and forward movement is provided, and the rotary motion of the rotor is transmitted to the writing core via the chuck. The mechanical pencil according to any one of claims 1 to 6.

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