Pencil sharpener with automatic lead breakage removal

Abstract

A pencil sharpener with automatic pencil lead breakage discharging function, comprising a knife rest, a blade and a fixing screw. The blade is fixed on the knife rest by the fixing screw. The knife rest is provided with a lead discharging groove and a conical pencil sharpening hole. The pencil sharpening hole includes a first hole section and a second hole section. The second hole section communicates with the end of the first hole section. The hole wall of the first hole section includes a first arc wall and a second arc wall. The hole wall of the second hole section includes a third arc wall. The third arc wall is located in the extending direction of the first arc wall. A groove is provided on the hole wall of the second hole section. The groove is located in the extending direction of the second arc wall. After adopting the above structure, compared with the prior art, the beneficial effect is that the pencil lead will not be stuck in the pencil sharpening hole after being broken in the pencil sharpener, avoiding the trouble of manually removing the broken lead.

Description

Technical Field

[0001] The present invention relates to the technical field of stationery, and particularly to a pencil sharpener. Background Art

[0002] The use of a pencil sharpener to sharpen pencils has been widely applied because it is small and portable and suitable for primary school students. During the process of sharpening a pencil, due to uneven control of the force during the pencil sharpening process or excessive wear of the blade of the pencil sharpener, the pencil lead may break. The diameter of the lead of a conventional pencil is 2.1 mm; the minimum inner diameter of the pencil sharpening hole of the existing pencil sharpener is 1.9 mm; in order to cut the pencil, the blade descends by 0.2 mm, so the distance between the blade and the inner wall of the pencil sharpening hole of the pencil sharpener is 1.7 mm. When the pencil lead breaks during sharpening, the broken lead (with a diameter of 2.1 mm) will get stuck between the blade and the blade holder, and then it is necessary for people to remove the lead, which is very troublesome, and the broken lead will cause wear to the blade. Summary of the Invention

[0003] The present invention provides a pencil sharpener that can automatically discharge the broken lead of a pencil for the above problems.

[0004] The technical solution adopted by the present invention to solve the above problems is: a pencil sharpener for automatically discharging the broken lead of a pencil, including a blade holder, a blade and a fixing screw. The blade is fixed on the blade holder through the fixing screw. The blade holder is provided with a lead discharging groove and a conical pencil sharpening hole. The pencil sharpening hole includes a first hole section and a second hole section. The second hole section communicates with the end of the first hole section. The hole wall of the first hole section includes a first arc wall and a second arc wall. The hole wall of the second hole section includes a third arc wall. The third arc wall is located in the extending direction of the first arc wall. A groove is provided on the hole wall of the second hole section. The groove is located in the extending direction of the second arc wall. The lead discharging groove is located in the extending direction of the pencil sharpening hole and communicates with the groove. The blade is located above the second arc wall, the groove and the lead discharging groove. The blade and the first hole section together form a first pencil sharpening section. The blade and the second hole section, the lead discharging groove together form a second pencil sharpening section. The maximum inscribed circle diameter of any cross-section of the first pencil sharpening section and the second pencil sharpening section in the axial direction of the pencil sharpening hole is greater than the diameter of the pencil lead.

[0005] The pencil sharpening hole of the pencil sharpener of the present invention includes a first hole section and a second hole section. A groove is provided on the hole wall of the second hole section. During the process of sharpening a pencil with the pencil sharpener, the pencil mainly abuts against the first arc wall and the third arc wall, and there is no force acting on one side of the second arc wall. Therefore, the setting of the groove will not affect the function of the pencil sharpener in cutting the pencil. After the groove is provided, the aperture at the end of the first hole section and the aperture of the second hole section are larger than the diameter of the pencil lead. The first pencil sharpening section is a space formed by the blade and the first hole section, and the second pencil sharpening section is a space formed by the blade, the second hole section and the chip discharge groove. The cross-section of the first pencil sharpening section and the second pencil sharpening section in the axial direction of the pencil sharpening hole is a polygon with an arc-shaped side, and the diameter of its largest inscribed circle is larger than the diameter of the pencil lead. Therefore, the broken core will not be stuck in the pencil sharpening hole, and the broken core can fall into the groove and be discharged from the chip discharge groove. After adopting the above structure, the beneficial effect compared with the prior art is that the pencil lead will not be stuck in the pencil sharpening hole after being broken in the pencil sharpener, avoiding the trouble of manually removing the broken core.

[0006] Preferably, the distance between the point where the blade edge is located and the lower end point of the third arc wall on the cross-section at one end of the second pencil sharpening section close to the first pencil sharpening section is greater than the diameter of the pencil lead, and the center point of this connection line is located on the side of the pencil lead axis close to the third arc wall.

[0007] Preferably, the length of the third arc wall in the extension direction of the first arc wall is greater than or equal to 0.5 mm. The length of the third arc wall being greater than or equal to 0.5 mm can ensure that the tip of the pencil has enough force-bearing space, avoiding broken cores and ensuring the length of the tip.

[0008] Preferably, the third arc wall and the first arc wall are on the same curved surface. The first arc wall, the second arc wall and the third arc wall are all on the side surface of the same cone, ensuring smooth pencil sharpening.

[0009] Preferably, the chip discharge groove is in the extension direction of the second arc wall, and at least one inclined surface or arc surface is formed on the knife rest at the same time. The cross-sectional area of at least one section of the second pencil sharpening section formed thereby gradually increases in the axial direction of the pencil sharpening hole. Such a setting is beneficial for the discharge of broken cores and the shavings removed.

[0010] Preferably, an indentation is provided on the groove wall of the chip discharge groove, and the indentation is in the extension direction of the third arc wall. The indentation is connected to the third arc wall and extends in its extension direction.

[0011] Preferably, the cross-section of the indentation is arc-shaped, and the diameter of the circle corresponding to the arc is less than or equal to the diameter of the pencil lead of the pencil being sharpened. The indentation plays a role in protecting the tip of the pencil and avoiding broken cores. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic structural diagram of the pencil sharpener for automatically discharging pencil broken cores of the present invention.

[0013] Figure 2 Explosion view of the pencil sharpener for automatically discharging broken pencil leads according to the present invention.

[0014] Figure 3 is Figure 1 Cross-sectional view taken along line A-A of

[0015] Figure 4 is Figure 3 Enlarged view of part X in

[0016] Figure 5 Cross-sectional view of the pencil sharpener for automatically discharging broken pencil leads according to the present invention in another direction.

[0017] Figure 6 is Figure 4 Cross-sectional view of the first pencil sharpening section taken along line B-B of

[0018] Figure 7 is Figure 4 Cross-sectional view of the second pencil sharpening section taken along line C-C of

[0019] Figure 8 is Figure 4 Cross-sectional view of the second pencil sharpening section taken along line D-D of

[0020] Figure 9 Schematic structural diagram of Embodiment II of the present invention.

[0021] Figure 10 Schematic structural diagram of Embodiment III of the present invention.

[0022] As shown in the figure: 1. Knife rest, 2. Blade, 3. Fixing screw, 4. Pencil sharpening hole, 4a. First pencil sharpening section, 4b. Second pencil sharpening section, 41. First hole section, 411. First arc wall, 412. Second arc wall, 42. Second hole section, 421. Third arc wall, 422. Groove, 4221. Curved surface wall, 4222. Straight wall, 5. Chip discharging groove, 51. Concave. Specific embodiments

[0023] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0024] Embodiment I

[0025] As Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 8As shown in the figure, a pencil sharpener for automatically discharging broken pencil leads includes a knife rest 1, a blade 2, and a fixing screw 3. The blade 2 is fixed on the knife rest 1 by the fixing screw 3. A lead discharging groove 5 and a conical pencil sharpening hole 4 are provided on the knife rest 1. The pencil sharpening hole 4 includes a first hole section 41 and a second hole section 42. The second hole section 42 communicates with the end of the first hole section 41. The end of the first hole section 41 refers to the end far from the orifice of the pencil sharpening hole 4. The hole wall of the first hole section 41 includes a first arc wall 411 and a second arc wall 412. The hole wall of the second hole section 42 includes a third arc wall 421. The third arc wall 421 is located in the extending direction of the first arc wall 411. A groove 422 is provided on the hole wall of the second hole section 42. The groove 422 is located in the extending direction of the second arc wall 412. The lead discharging groove 5 is located in the extending direction of the pencil sharpening hole 4 and communicates with the groove 422. The third arc wall 421 is on the extending plane of the first arc wall 411. The third arc wall 421 and the first arc wall 411 are on the same curved surface. The first arc wall 411, the second arc wall 412, and the third arc wall 421 are all on the side surface of the same cone.

[0026] The blade 2 is located above the second arc wall 412, the groove 422, and the lead discharging groove 5. The blade 2 and the first hole section 41 together form a first pencil sharpening section 4a. The blade 2, the second hole section 42, and the lead discharging groove 5 together form a second pencil sharpening section 4b. The first pencil sharpening section 4a is a space formed by the blade 2 and the first hole section 41. The second pencil sharpening section 4b is a space formed by the blade 2, the second hole section 42, and the lead discharging groove 5. The maximum inscribed circle diameter of any cross-section of the first pencil sharpening section 4a and the second pencil sharpening section 4b in the axial direction of the pencil sharpening hole 4 is greater than the diameter of the pencil lead to be sharpened.

[0027] In this example Figure 6 is Figure 4 a cross-sectional view of the first pencil sharpening section taken along the B-B line of Figure 7 is Figure 4 a cross-sectional view of the second pencil sharpening section taken along the C-C line of Figure 8 is Figure 4 a cross-sectional view of the second pencil sharpening section taken along the D-D line of Figure 6 That is, a cross-sectional view of the second pencil sharpening section 4b near the first pencil sharpening section 4a. The cross-section of the first pencil sharpening section 4a in the axial direction of the pencil sharpening hole 4 is a polygon with an arcuate side. The side where the blade 2 is located and the side where the hole wall of the pencil sharpening hole 4 is located have an inscribed circle, as Figure 7 shown in Figure 8C2 shown in the figure, the diameter of the largest inscribed circle C2 within the polygon is greater than the diameter of the pencil lead d. On the cross-section of the second pencil-sharpening section 4b near one end of the first pencil-sharpening section 4a, the distance from the point where the blade 2's cutting edge is located to the lower end point of the third arc wall 421 is greater than the diameter of the pencil lead d. And the center point of this connection line is located on the side of the pencil lead d's axis o near the third arc wall 421. As Figure 8 shown, the lower end point n1 of the third arc wall 421, the point where the blade 2's cutting edge is located is at n2, the connection line S between n1 and n2, the length of the connection line S is greater than the diameter of the pencil lead d. The center point of the connection line S is on the side of the pencil lead axis o near the third arc wall 421, that is Figure 8 on the right side of the pencil lead axis o in the figure. On the cross-section of the first pencil-sharpening section 4a near one end of the second pencil-sharpening section 4b, the distance from the point where the blade 2's cutting edge is located to the lower end point of the second arc wall 412 is greater than the diameter of the pencil lead.

[0028] A core discharge groove 5 is provided at the end of the knife rest 1, and the core discharge groove 5 communicates with the second hole section 42. The bottom of the core discharge groove 5 and one side wall of the groove are respectively flush with two of the inner walls of the groove 422. An indentation 51 is provided on the side wall of the core discharge groove 5 on the extension direction side of the third arc wall 521.

[0029] The length of the third arc wall 421 in the extension direction of the first arc wall 411 is greater than 0.5 mm, which can ensure that there is sufficient stress space for the pencil tip, avoid lead breakage and ensure the tip length.

[0030] The diameter of the pencil lead is 2.1 mm. The diameter of the largest inscribed circle c1 of any cross-section of the first pencil-sharpening section 4a of the pencil sharpener for automatically discharging broken pencil leads of the present invention in the axial direction of the pencil-sharpening hole 4 is greater than 2.1 mm. The diameter of the end of the first hole section 41 is between 2.65 mm and 2.85 mm, the diameter of the largest inscribed circle of the cross-section at the end of the first pencil-sharpening section 4a is between 2.35 mm and 2.65 mm, the diameter of the end of the second hole section 42 is between 1.8 mm and 2.0 mm, and the diameter of the largest inscribed circle of the cross-section at the end of the second pencil-sharpening section 4b is between 2.55 mm and 2.75 mm. In this example, the length of the third arc wall 421 in the extension direction of the first arc wall 411 is 2 mm, the diameter of the end of the first hole section 41 is 2.78 mm, the width of the groove 422 is 1.21 mm, the width of the core discharge groove 5 is 2.48 mm, the diameter of the largest inscribed circle of the cross-section at the end of the first pencil-sharpening section 4a is 2.53 mm, the diameter of the end of the second hole section 42 is 1.93 mm, and the diameter of the largest inscribed circle of the cross-section at the end of the second pencil-sharpening section 4b is 2.68 mm.

[0031] During the process of sharpening a pencil, the pencil mainly abuts against the first arc wall 411 and the third arc wall 421. There is no force acting on one side of the second arc wall 412. Therefore, the setting of the groove 422 will not affect the function of the pencil sharpener in sharpening the pencil. After the groove 422 is set, the aperture diameters of the end of the first hole section 41 and the second hole section 42 are larger than the diameter of the pencil lead. Therefore, the broken lead will not get stuck in the pencil sharpening hole, but will directly fall into the groove 422 and fall out of the pencil sharpener through the lead discharge groove 5.

[0032] Embodiment 2

[0033] As Figure 9 shown, the lead discharge groove 5 is in the extending direction of the second arc wall 412, and at the same time forms a curved surface on the knife rest 1. The cross-sectional area of the second pencil sharpening section 4b formed thereby gradually increases in the axial direction of the pencil sharpening hole 4. The cross-sectional area of the end of the lead discharge groove 5 far from the pencil sharpening hole 4 is larger than the cross-sectional area of the end of the lead discharge groove 5 close to the pencil sharpening hole 4. The groove 422 is composed of a curved surface wall 4221 and a straight wall 4222. The groove wall of the lead discharge groove 5 forms a curved surface on the knife rest 1. This curved surface is a part of a conical surface, on the extended surface of the curved surface wall 4221 of the groove 422, and on the same conical surface as the curved surface wall 4221 of the groove 422. After the broken lead falls into the groove 422, it directly falls out of the pencil sharpener through the lead discharge groove 5 by using the conical surface.

[0034] Embodiment 3

[0035] As Figure 10 shown, the bottom of the lead discharge groove 5 and the two side groove walls are respectively flush with the three inner side walls of the groove 422. An indentation 51 is provided on one side groove wall of the lead discharge groove 5, and the indentation 51 is in the extending direction of the third arc wall 521. The indentation 51 is connected to the third arc wall 521 and extends in its extending direction. The cross-section of the indentation 51 is arc-shaped, and the diameter of the circle corresponding to the arc is smaller than the diameter of the pencil lead to be sharpened, between 1.8 mm and 2.0 mm. In this example, the diameter of the circle corresponding to the arc is 1.93 mm.

Claims

1. A pencil sharpener for automatically discharging broken pencil leads, comprising a knife rest (1), a blade (2) and a fixing screw (3), wherein the blade (2) is fixed on the knife rest (1) by the fixing screw (3), and a lead discharging groove (5) and a conical pencil sharpening hole (4) are provided on the knife rest (1); It is characterized in that: The pencil sharpening hole (4) includes a first hole section (41) and a second hole section (42), the second hole section (42) communicates with the end of the first hole section (41), the hole wall of the first hole section (41) includes a first arc wall (411) and a second arc wall (412), the hole wall of the second hole section (42) includes a third arc wall (421), the third arc wall (421) is located in the extension direction of the first arc wall (411), a groove (422) is provided on the hole wall of the second hole section (42), the groove (422) is located in the extension direction of the second arc wall (412), the lead discharging groove (5) is located in the extension direction of the pencil sharpening hole (4) and communicates with the groove (422), the blade (2) is located above the second arc wall (412), the groove (422) and the lead discharging groove (5), the blade (2) and the first hole section (41) together form a first pencil sharpening section (4a), the blade (2) and the second hole section (42), the lead discharging groove (5) together form a second pencil sharpening section (4b), and the maximum inscribed circle diameter of any cross-section of the first pencil sharpening section (4a) and the second pencil sharpening section (4b) in the axial direction of the pencil sharpening hole (4) is greater than the diameter of the pencil lead.

2. The pencil sharpener for automatically discharging pencil lead breakage according to claim 1, wherein: The distance between the point where the blade edge of the blade (2) is located and the lower end point of the third arc wall (421) on the cross-section near the first pencil sharpening section (4a) of the second pencil sharpening section (4b) is greater than the diameter of the pencil lead, and the center point of this connection line is located on the side of the pencil lead axis near the third arc wall (421).

3. The pencil sharpener for automatically discharging broken pencil leads according to claim 1, characterized in that: The length of the third arc wall (421) in the extension direction of the first arc wall (411) is greater than or equal to 0.5 mm.

4. The pencil sharpener for automatically discharging broken pencil leads according to claim 1, wherein: The third arc wall (421) and the first arc wall (411) are on the same curved surface.

5. The pencil sharpener for automatically discharging broken pencil leads according to claim 1, wherein: The lead discharging groove (5) is in the extension direction of the second arc wall (412), and at least one inclined surface or arc surface is formed on the knife rest (1) at the same time, so that the cross-sectional area of at least one section of the second pencil sharpening section (4b) formed in this way gradually increases in the axial direction of the pencil sharpening hole (4).

6. The pencil sharpener for automatically discharging broken pencil leads according to claim 1, characterized in that: An indentation (51) is provided on the groove wall of the lead discharging groove (5), and the indentation (51) is in the extension direction of the third arc wall (421).

7. The pencil sharpener for automatically discharging pencil lead breakage according to claim 6, characterized in that: The cross-section of the indentation (51) is arc-shaped, and the diameter of the circle corresponding to the arc is less than or equal to the diameter of the pencil lead.

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