Core metal, elastic roller, and method for manufacturing elastic roller

Abstract

To provide a core grid capable of being used for an elastic body roller, which can fit a core grid and an elastic coating material without using an adhesive, can suppress occurrence of failure due to air left between the core grid and the elastic coating material (the raw material of the elastic coating material), and can discharge the air present between the core grid and the elastic coating material in a short period, an elastic body roller having such a core grid, and a manufacturing method for an elastic body roller.SOLUTION: A core grid 2 for an elastic roller 1 has a shaft-shaped core grid body 11, and an air passage 3 open to both an outer peripheral surface 11c of the core grid body 11 and end surfaces 11a, 11b of the core grid body 11.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a core bar, an elastic roller, and a method for manufacturing an elastic roller. [Background technology]

[0002] 2. Description of the Related Art Image forming apparatuses such as copiers, printers, multifunction machines, facsimiles, etc. include various rollers, of which a rubber-covered roller having a rubber tube fitted onto the outer circumferential surface of a core metal is known.

[0003] Rubber-covered rollers include one in which a core metal and a rubber tube are bonded with an adhesive or the like, and one in which a core metal and a rubber tube are press-fitted together, as described in Patent Document 1. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4908782 specification Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, in the configuration in which the core bar and the rubber tube are bonded with an adhesive, it is necessary to introduce equipment such as an applicator for applying the adhesive. In addition, many processes such as a heat application process for hardening the adhesive are required. Furthermore, if the rubber tube bonded to the core bar is defective due to processing, the core bar cannot be recycled. As a result, the manufacturing cost of the rubber-covered roller is high.

[0006] On the other hand, as described in Patent Document 1, in a configuration in which a rubber tube is press-fitted into a core bar, the rubber tube is first attached onto the outer circumferential surface of the core bar. At this time, compressed air is blown between the core bar and the rubber tube to expand the rubber tube, making it easier for the rubber tube to fit into the core bar. Next, an O-ring is fitted onto the rubber tube. Then, the O-ring is moved from one end of the rubber tube to the other end while being tightened by hand or the like to expel any air remaining between the core bar and the rubber tube.

[0007] As described in Patent Document 1, in the case of a configuration in which the core bar and the rubber tube are fitted together by press-fitting without using an adhesive, the air between the core bar and the rubber tube may not be completely discharged depending on the thickness and hardness of the rubber tube and the shape of the core bar. For example, a rubber tube longer than the length of the core bar may be fitted onto the core bar, and then the rubber tube may be cut to make the length of the rubber tube the same as that of the core bar. In this case, the part (ear) of the rubber tube protruding from the core bar bends to block the outer periphery of the end of the core bar as described above. For this reason, in the deaeration process in which the air between the rubber tube and the core bar is discharged using an O-ring as described above, the air between the rubber tube and the core bar is difficult to escape from the end of the core bar. In particular, when the rubber tube is soft, the ear of the rubber tube strongly blocks the outer periphery of the end of the core bar, making it difficult for the air to escape between the rubber tube and the core bar. As a result, air may remain between the rubber tube and the core bar at the end of the core bar.

[0008] If air remains between the rubber tube and the core, the degree of adhesion between the rubber tube and the core may be low when the rubber tube pressed into the core is subjected to finishing processing, etc., and the rubber tube may twist or move relative to the core. In order to fully exhaust the air between the core and the rubber tube, it is possible to take the time to exhaust this air in a deaeration process, but taking such time would increase the time required to manufacture the rubber-covered roller.

[0009] In light of this background, the present invention provides a core bar that can be used for an elastic roller, which can engage the core bar and the elastic covering material without using adhesive, which can suppress the occurrence of defects caused by air remaining between the core bar and the elastic covering material (the material of the elastic covering material), and which can expel air that exists between the core bar and the elastic covering material in a short period of time, an elastic roller having this core bar, and a method for manufacturing an elastic roller. [Means for solving the problem]

[0010] The present invention relates to the following core bar, an elastic roller having the core bar, and a method for manufacturing the elastic roller.

[0011] (1) A core bar for an elastic roller, A shaft-shaped core body, an air passage opening to both an outer circumferential surface of the core body and an end surface of the core body; A core bar is provided.

[0012] (2) The core bar described in (1) above, wherein the air passage includes a groove extending along the axial direction of the outer circumferential surface.

[0013] (3) The core bar according to (2) above, wherein the marking groove is formed over the entire axial length of the core bar body.

[0014] (4) The marking grooves include a first marking groove that opens on an end face on one axial end side of the core body, and a second marking groove that opens on an end face on the other axial end side of the core body, The core bar described in (2) above, wherein the first marking groove and the second marking groove are spaced apart from each other.

[0015] (5) A core bar as described in (2) above, wherein the marking groove is open on an end face at one axial end of the core bar body and closed on an end face at the other axial end of the core bar body.

[0016] (6) A core bar described in any one of (2) to (5), wherein, when viewed from the axial direction of the core bar, the width of the marking groove is 0.1 mm to 2.2 mm, the depth of the marking groove is 0.02 mm to 0.50 mm, and the value obtained by dividing the depth by the width is 0.03 or more.

[0017] (7) The core bar according to any one of (2) to (6), wherein the length of the scribed groove in the axial direction of the core bar body is 7 mm or more.

[0018] (8) A core bar according to any one of (1) to (7), further comprising a core bar end portion protruding from an axial end face of the core bar body and having an outer diameter smaller than the outer diameter of the core bar body.

[0019] (9) a hollow elastic covering; An elastic roller comprising: the core metal according to any one of (1) to (8) above, the elastic covering material being fitted onto the core metal body.

[0020] (10) A preparation step of preparing a hollow elastic covering material and the core bar described in any one of (1) to (8); a press-fitting step of press-fitting the elastic covering material onto the core by fitting an inner peripheral surface of the elastic covering material onto an outer peripheral surface of the core body; a deaeration step of discharging air between the core bar and the elastic covering material through the air passage; The method for manufacturing an elastic roller includes the steps of: Effect of the Invention

[0021] According to the present invention, when manufacturing an elastic roller, the core bar and the elastic covering material can be fitted together without using adhesive, the occurrence of defects caused by air remaining between the core bar and the elastic covering material (the material of the elastic covering material) can be suppressed, and air present between the core bar and the elastic covering material can be expelled in a short period of time. [Brief description of the drawings]

[0022] [Figure 1]Fig. 1(A) is a front view of an elastic roller according to an embodiment of the present invention, with a part broken away, and Fig. 1(B) is a partially sectional side view of the elastic roller. [Diagram 2] FIG. 2 is an enlarged front view showing a main part of the elastic roller. [Diagram 3] 3 is a cross-sectional view showing a part of the core metal of the elastic roller taken along the line III-III in FIG. [Figure 4] 4(A) and 4(B) are diagrams for explaining a method for manufacturing the elastic roller. [Diagram 5] 5(A) and 5(B) are diagrams for explaining a method for manufacturing the elastic roller. [Figure 6] FIG. 6 is a diagram showing a first modified example of the elastic roller. [Figure 7] FIG. 7 is a diagram showing a second modified example of the elastic roller. [Figure 8] FIG. 8 is a graph showing an image of the run-out amount measurement result obtained by the measuring device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this specification and the drawings, components having substantially the same functional configurations are designated by the same reference numerals, and duplicated explanations will be omitted.

[0024] Fig. 1(A) is a front view of an elastic roller 1 according to one embodiment of the present invention, with a part broken away. Fig. 1(B) is a side view of the elastic roller 1. Fig. 2 is a partially cross-sectional front view showing an enlarged view of a main part of the elastic roller 1. Fig. 3 is a cross-sectional view showing a part of the core metal 2 of the elastic roller 1 along the line III-III in Fig. 2.

[0025] 1(A) to 3, the elastic roller 1 is provided in an image forming apparatus such as a copier, a printer, a multifunction machine, or a facsimile. The elastic roller 1 may be used, for example, as a charging roller for charging a photosensitive drum, a developing roller for supplying toner to the photosensitive drum, or a transfer roller for transferring a toner image from the photosensitive drum to a sheet of paper. The elastic roller 1 may also be used as an opposing roller disposed opposite a transfer roller. The elastic roller 1 may also be a driving roller driven by an electric motor provided in the image forming apparatus, or a driven roller that rotates by receiving a force from a conveyed transfer belt or the like.

[0026] The elastic roller 1 has a core 2 , an air passage 3 formed in the core 2 , and an elastic covering material 4 arranged on the outer periphery of the core 2 .

[0027] The core metal 2 is a core metal for the elastic roller 1, and is made of metal, synthetic resin, etc. The hardness of the core metal 2 only needs to be sufficiently high compared to the hardness of the elastic covering material 4, and it is treated as a rigid body relative to the elastic covering material 4.

[0028] The core 2 has a shaft-shaped core body 11 and core end portions 12a, 12b which protrude from axial end faces 11a, 11b of the core body 11 and have an outer diameter smaller than that of the core body 11.

[0029] In this embodiment, the core bar 2 is formed using a cylindrical member 5 constituting a part of the outer circumferential side of the end faces 11a, 11b of the core bar body 11 and the outer circumferential surface 11c, and a pair of end members 6a, 6b fixed to both ends of the cylindrical member 5 by press-fitting or the like and constituting a part of the inner circumferential side of the end faces 11a, 11b and the core bar ends 12a, 12b. The end members 6a, 6b may be omitted, and the core bar 2 may be formed by the cylindrical member 5. The cylindrical member 5 may be hollow or solid. The core bar 2 may be an integrally molded product formed as a whole in one part.

[0030] The core bar ends 12a, 12b protrude from a pair of end faces 11a, 11b of the core bar body 11 in the axial direction A of the elastic roller 1 (hereinafter, simply referred to as the axial direction A). The core bar ends 12a, 12b are portions supported by bearings or the like (not shown) provided in the image forming apparatus. In this embodiment, each of the core bar ends 12a, 12b includes a portion having a relatively small outer diameter and a portion having a relatively large outer diameter, and the portion having a relatively large outer diameter is continuous with the corresponding end face 11a, 11b of the core bar body 11. The shape of the core bar ends 12a, 12b is not particularly limited, and the core bar ends 12a, 12b may be symmetrical or asymmetrical in the axial direction A.

[0031] The core metal body 11 is a portion on which the elastic covering material 4 is press-fitted to cover. The core metal body 11 is a portion of the core metal 2 with the largest outer diameter, and has an outer diameter larger than the maximum outer diameter of the core metal ends 12a, 12b. In this embodiment, the outer circumferential surface 11c of the core metal body 11 is a cylindrical surface. The diameter of the outer circumferential surface 11c of the core metal body 11 (the outer diameter of the core metal 2) is, for example, about 6 to 50 mm. The total length of the core metal body 11 (the length in the axial direction A) is, for example, about 200 mm to about 1000 mm. The pair of end faces 11a, 11b of the core metal body 11 are annular flat surfaces disposed perpendicular to the axial direction A. The pair of end faces 11a, 11b may be tapered along the axial direction A so that the outer diameter becomes smaller as it approaches the corresponding core metal ends 12a, 12b.

[0032] In this embodiment, the air passage 3 is open to both the outer peripheral surface 11c of the core bar body 11 and the end faces 11a, 11b of the core bar body 11. The air passage 3 is provided to allow air to flow from the outer peripheral surface 11c of the core bar 2 to the end faces 11a, 11b. More specifically, the air passage 3 is provided to exhaust air that exists between the cylindrical material 40, which is the material of the elastic covering material 4, and the outer peripheral surface 11c when the outer peripheral surface 11c of the core bar body 11 is covered with the cylindrical material 40.

[0033] As described below, the cylindrical material 40 is press-fitted into the core body 11, and then the ears 41a and 41b at both ends are cut off and the outer circumferential surface is polished to become the elastic covering material 4. The inner diameter of the cylindrical material 40 in a free state in which no external force is acting is smaller than the outer diameter of the core body 11. Immediately after the cylindrical material 40 is press-fitted into the core body 11, both ends of the cylindrical material 40 protrude from the core body 11 in the axial direction A, and these protruding parts become the ears 41a and 41b. The ears 41a and 41b are bent at both ends of the core body 11 in the axial direction A so as to clamp the outer circumferential surface 11c of the core body 11. As a result, the ears 41a and 41b clamp the outer circumferential edges of the pair of end faces 11a and 11b, and the flow of air between the cylindrical material 40 and the pair of end faces 11a and 11b is prevented.

[0034] In this embodiment, the air passage 3 is a scribed groove extending along the axial direction A of the outer circumferential surface 11c. In this specification, the "scribed groove" refers to an elongated linear groove, and the method of formation is not limited. The air passage 3 may be formed by a tool for carving a scribed groove, or may be formed by a cutting tool of a machine tool. In this embodiment, the air passage 3 is formed over the entire axial area of ​​the core metal body 11. The air passage 3 is open to an end face 11a on one axial end side of the core metal body 11, and is also open to an end face 11b on the other axial end side of the core metal body 11. In this embodiment, the air passage 3 is formed parallel to the axial direction A. The air passage 3 is not completely blocked by the ears 41a and 41b of the cylindrical material 40, and at least a part of the air passage 3 is open to the outside of the core metal body 11.

[0035] In this embodiment, one air passage 3 is provided, but this is not necessarily the case. For example, the air passage 3 may be formed at a plurality of locations on the core metal body 11 in the circumferential direction of the elastic roller 1. Furthermore, the air passage 3 may extend along the axial direction A but may not be parallel to the axial direction A, for example, by being formed in a spiral shape on the outer circumferential surface of the core metal body 11.

[0036] When the core metal body 11 is viewed in a cross section perpendicular to the axial direction A (hereinafter also referred to as an axial cross section; cross section shown in FIG. 3), the air passage 3 is formed in a V-shape, U-shape, W-shape, or the like. In the axial cross section, the air passage 3 is a fine groove, and is formed by cutting the outer circumferential surface 11c of the core metal body 11 with a tool such as a cutting tool, as described above. For this reason, the shape of the air passage 3 is influenced by the shape of the tool. In this embodiment, the shape of the air passage 3 in the axial cross section is formed in a V-shape with no angular edges.

[0037] In the axial cross section, that is, as viewed from the axial direction of the core 2, the width W of the air passage 3 is preferably 0.1 mm to 2.2 mm. When the width W is 0.1 mm or more, air can smoothly pass through the air passage 3, and the air between the ears 41a, 41b of the cylindrical material 40 and the outer circumferential surface 11c of the core body 11 can be reliably discharged from between the cylindrical material 40 and the core body 11. When the width W is 2.2 mm or less, the width of the air passage 3 can be prevented from becoming too large. This makes it possible to extremely reduce the degree to which the cylindrical material 40 is deformed so as to be recessed due to the cylindrical material 40 entering the air passage 3 when the outer circumferential surface of the cylindrical material 40 pressed into the core 2 is ground by pressing a tool such as a grindstone against the outer circumferential surface of the cylindrical material 40 to form the cylindrical material 40 into the elastic covering material 4. As a result, the dimensional accuracy of the outer circumferential surface of the elastic covering material 4 can be increased. The lower limit of the width W of the air passage 3 is more preferably 0.5 mm, more preferably 1.2 mm. Moreover, the upper limit of the width W of the air passage 3 is more preferably 1.85 mm.

[0038] In the axial cross section, the depth D of the air passage 3 is preferably 0.02 mm to 0.50 mm. When the depth D is 0.02 mm or more, air can smoothly pass through the air passage 3, and the air between the cylindrical material 40 and the outer peripheral surface 11c of the core body 11 can be reliably discharged from between the cylindrical material 40 and the core body 11. When the depth D is 0.50 mm or less, the air passage 3 can be prevented from becoming too deep. This makes it possible to extremely reduce the degree to which the cylindrical material 40 is deformed so as to be recessed due to the cylindrical material 40 entering the air passage 3 when the outer peripheral surface of the cylindrical material 40 pressed into the core 2 is ground by pressing a tool such as a grindstone against the outer peripheral surface of the cylindrical material 40 to form the cylindrical material 40 into the elastic covering material 4. As a result, the dimensional accuracy of the outer peripheral surface of the elastic covering material 4 can be increased. The lower limit of the depth D of the air passage 3 is more preferably 0.15 mm, more preferably 0.25 mm. Moreover, the upper limit of the depth D of the air passage 3 is more preferably 0.45 mm, and more preferably 0.30 mm.

[0039] In this embodiment, it is more preferable to take into consideration the ratio of the width W and the depth D of the air passage 3 in terms of smoothly discharging the air between the cylindrical material 40 and the core metal body 11. Specifically, it is preferable that the value D / W obtained by dividing the depth D of the air passage 3 by the width W is 0.03 or more. As described above, when the cylindrical material 40 is pressed into the outer circumferential surface 11c of the core metal body 11, the gap between the axial end of the outer circumferential surface 11c of the core metal body 11 and the ears 41a, 41b of the cylindrical material 40 is blocked by the ears 41a, 41b. However, even in this state, since the value D / W is 0.03 or more, the air passage 3 has a sufficient depth D relative to the width W, and the outer circumferential edge of the end faces 11a, 11b is not blocked by the cylindrical material 40, and the air can be more reliably discharged to the outside from between the cylindrical material 40 and the core metal 2.

[0040] In this embodiment, the length L of the air passage 3 in the axial direction A is preferably 7 mm or more. When the cylindrical material 40 is fitted into the core bar body 11, the ears 41a, 41b close the outer peripheral edges of the end faces 11a, 11b of the core bar body 11, so that air tends to accumulate at the ends of the core bar body 11 in the axial direction A between the core bar body 11 and the cylindrical material 40. Even in this case, by making the length L 7 mm or more, air can be more reliably discharged from the places where air tends to accumulate. In this embodiment, the length L is the same as the overall length of the core bar body 11.

[0041] The elastic covering material 4 is a portion on which an image forming agent such as toner or a transfer belt is placed. The elastic covering material 4 is a cylindrical shaft-shaped member formed in a hollow shape. The elastic covering material 4 is fitted on the outer peripheral surface 11c of the core metal body 11. The elastic covering material 4 is arranged over the entire area of ​​the core metal body 11 in the axial direction A. One end surface 4a of the elastic covering material 4 in the axial direction A may be arranged at a position about 5 mm inward (toward the center of the core metal body 11 in the axial direction A) or outward from one end surface 11a of the core metal body 11 in the axial direction A. Similarly, the other end surface 4b of the elastic covering material 4 in the axial direction A may be arranged at a position about 5 mm inward or outward from the other end surface 11b of the core metal body 11 in the axial direction A. When the elastic covering material 4 is not attached to the core metal body 11, the inner diameter of the elastic covering material 4 is smaller than the outer diameter of the core metal body 11, and the inner diameter is expanded by fitting the elastic covering material 4 to the core metal body 11. In this way, the elastic covering material 4 is press-fitted into the core bar body 11. The thickness of the elastic covering material 4 when press-fitted into the core bar body 11 is, for example, about several mm, but the specific value is not limited.

[0042] Examples of materials for the elastic covering material 4 include synthetic rubber such as NBR, epichlorohydrin rubber, polyurethane, EPDM, other synthetic rubbers, and sponge. The hardness of the elastic covering material 4 is not particularly limited, but when the elastic covering material 4 is made of rubber, the hardness can be, for example, 40 to 80 in Durometer A hardness. When the elastic covering material 4 is made of sponge, the hardness can be, for example, 20 to 80 in Asker C hardness.

[0043] The lower the hardness of the elastic covering material 4, the higher the degree to which the outer peripheral edge of the pair of end faces 11a, 11b of the core bar body 11 is covered by the ears 41a, 41b at both ends of the cylindrical material 40 so as to be fastened thereto. For this reason, even when the elastic covering material 4 has the smallest hardness and is soft among the above hardnesses, it is necessary to prevent the air passage 3 from being blocked by the cylindrical material 40 at the end faces 11a, 11b. For such a configuration, it is preferable that the value D / W obtained by dividing the depth D by the width W is 0.03 or more, as described above.

[0044] A pair of end faces 4a, 4b of the elastic covering material 4 face each other in the radial direction of the air passage 3 and the core bar 2, or are located outside the air passage 3 in the axial direction A.

[0045] The above is a schematic configuration of the elastic roller 1. Next, an example of a method for manufacturing the elastic roller 1 will be described.

[0046] 4(A), in manufacturing the elastic roller 1, first, the core 2 and the cylindrical material 40 (hollow elastic covering material) are prepared (preparation step). The total length of the cylindrical material 40 is longer than the total length of the core body 11 by, for example, several mm to several cm.

[0047] Next, the cylindrical material 40 is press-fitted into the core body 11 by fitting the inner peripheral surface of the cylindrical material 40 into the outer peripheral surface 11c of the core body 11 (press-fitting process). At this time, the cylindrical material 40 is attached to the core body 11 while the inner diameter is expanded by blowing compressed air B from a nozzle 51 arranged on one end surface 40a side of the cylindrical material 40. After the core body 11 is fitted into the cylindrical material 40, the supply of compressed air is stopped, and the cylindrical material 40 tightens the core body 11, so that the cylindrical material 40 is press-fitted into the core body 11. As a result, as shown in FIG. 4(B), a manufacturing intermediate body 21 in which the cylindrical material 40 is fitted into the outer peripheral surface 11c of the core body 11 is completed. In the manufacturing intermediate body 21, the ears 41a and 41b of the cylindrical material 40 located near the end surfaces 11a and 11b of the core body 11 are elastically deformed so as to tighten both ends of the core body 11. In the intermediate production body 21, air C remains between the outer circumferential surface 11c of the core body 11 and the inner circumferential surface of the cylindrical material 40. This air remains there by, for example, supplying compressed air as described above.

[0048] Next, the intermediate product 21 is deaerated (air removal) (deaeration step). In the deaeration step, the intermediate product 21 is left to stand for several minutes, for example. As a result, the air C between the core body 11 and the cylindrical material 40 is discharged to the outside of the intermediate product 21 through the air passage 3.

[0049] The degassed manufacturing intermediate 21 is cut into a cylindrical material 40 as shown in FIG. 5(A). In the cutting, the ears 41a, 41b of the cylindrical material 40 are cut by a cutter 52. By cutting the ears 41a, 41b of the cylindrical material 40, the positions of the pair of end faces 40a, 40b of the cylindrical material 40 and the position of the pair of end faces 11a, 11b of the core body 11 are aligned. Note that the positions of the pair of end faces 40a, 40b of the cylindrical material 40 after cutting may be shifted within a range of about 0.5 mm in the axial direction A with respect to the positions of the corresponding end faces 11a, 11b of the core body 11. By cutting the cylindrical material 40, the manufacturing intermediate 21 becomes a final manufacturing intermediate 22.

[0050] 5(B), while rotating the final manufacturing intermediate body 22, the outer peripheral surface of the cylindrical material 40 is polished with a polishing tool 53, so that the outer diameter of the cylindrical material 40 becomes the outer diameter of the elastic covering material 4. As a result, the cylindrical material 40 becomes the elastic covering material 4, and the elastic roller 1 is completed.

[0051] As described above, according to this embodiment, the air passage 3 is open to both the outer peripheral surface 11c of the core body 11 and the end faces 11a, 11b of the core body 11. As a result, by simply leaving the manufacturing intermediate body 21 for a short time, the air between the cylindrical material 40 and the core body 11 can be discharged to the outside through the air passage 3. With this configuration, unlike the deaeration work in which the cylindrical material 40 is clamped manually or mechanically while the clamping position is moved from one end of the manufacturing intermediate body 21 to the other end to discharge the air, the effort and time required for deaeration can be reduced. Moreover, unlike the case of deaeration performed manually, the degree of deaeration does not vary depending on the skill of the worker, and the air passage 3 can provide stable deaeration performance. Therefore, the variation in quality of the elastic roller 1 can be reduced. In addition, since deaeration between the elastic covering material 4 and the core body 11 is reliably performed, the degree of adhesion between the elastic covering material 4 and the core body 11 can be increased. This prevents problems caused by air C remaining between the elastic covering material 4 and the core body 11. Examples of such problems include a problem in which the cylindrical material 40 is unintentionally indented and deformed at a location where air C is present during grinding of the cylindrical material 40, resulting in a decrease in the dimensional accuracy of the elastic covering material 4, a problem in which the cylindrical material 40 is twisted when cutting or grinding the cylindrical material 40, and a problem in which the cylindrical material 40 moves in the axial direction A relative to the core body 11 and becomes misaligned. As described above, the core 2 and the elastic covering material 4 can be fitted together without using an adhesive, the occurrence of problems caused by air remaining between the core 2 and the elastic covering material 4 can be suppressed, and the air present between the core 2 and the elastic covering material 4 (cylindrical material 40) can be discharged in a short period of time, thereby increasing the production efficiency of the elastic roller 1.

[0052] Moreover, according to this embodiment, the air passage 3 includes a scribed groove extending along the axial direction A. In this manner, the air passage 3 can be formed with a simple structure in which a scribed groove is formed on the outer circumferential surface 11c of the core body 11, i.e., the portion on which the elastic covering material 4 is to be placed.

[0053] In addition, in this embodiment, the scribed grooves that form the air passage 3 are formed over the entire axial length. With this configuration, the air between the core body 11 and the cylindrical material 40 can be more reliably and quickly exhausted through the air passage 3.

[0054] Furthermore, in this embodiment, the core 2 includes core ends 12a, 12b that protrude from axial end faces 11a, 11b of the core body 11 and have an outer diameter smaller than that of the core body 11. With this configuration, the shape of the core ends 12a, 12b, which are set to an outer diameter matching that of a bearing or the like that supports the elastic roller 1, and the shape of the core body 11 into which the elastic covering material 4 is press-fitted can each be freely set. This allows for a high degree of freedom in the design of the elastic covering material 4.

[0055] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and modifications, and various modifications are possible within the scope of the claims.

[0056] (1) In the above embodiment, an example has been described in which the air passage 3 is formed over the entire axial length of the core metal body 11. However, this does not have to be the case. FIG. 6 is a diagram showing a first modified example of the elastic roller. As shown in FIG. 6, an elastic roller 1A having a pair of scribed grooves may be used instead of the elastic roller 1. The elastic roller 1A differs from the elastic roller 1 in that the air passages 3A are formed only at both axial ends of the core metal body 11.

[0057] The air passage 3A has a first scribed groove 31 that is opened to an end face 11a on one axial end side of the core metal body 11, and a second scribed groove 32 that is opened to an end face 11b on the other axial end side of the core metal body 11. The first scribed groove 31 and the second scribed groove 32 are separated from each other. The first scribed groove 31 and the second scribed groove 32 each preferably have a length L of at least 7 mm or more in the axial direction A. The configurations of the first scribed groove 31 and the second scribed groove 32 correspond to the configuration of the air passage 3 of the embodiment in which the intermediate portion in the axial direction A is omitted, so detailed description will be omitted. Note that the first scribed groove 31 and the second scribed groove 32 are formed in a shape symmetrical with respect to the axial direction A, but may be asymmetrical with respect to the axial direction A. In addition, the cross-sectional shapes in a cross section perpendicular to the axial direction A may be different from each other. Further, although the positions of the first scribed groove 31 and the second scribed groove 32 in the circumferential direction of the core bar body 11 are aligned in this modified example, they may be different.

[0058] Even when the air passage 3A is formed by the first marking groove 31 and the second marking groove 32 arranged at a distance in the axial direction A, the air between the cylindrical material 40 and the core body 11 can be quickly discharged by the air passage 3A during the deaeration process.

[0059] (2) In the above embodiment and first modified example, the elastic covering material 4 is disposed over the entire area of ​​the core metal body 11 in the axial direction A. However, this does not have to be the case. FIG. 7 is a diagram showing a second modified example of the elastic roller. As shown in FIG. 7, an elastic roller 1B having an air passage 3B may be used instead of the elastic roller 1. Elastic roller 1B differs from elastic roller 1 in that the air passage 3B ends at the middle part 11d of the core metal body 11 and the overall length of elastic covering material 4B is shorter than the overall length of the core metal body 11.

[0060] One end surface 4a of the elastic covering material 4B is disposed near one end surface 11a of the core metal body 11 and directly faces the air passage 3B. The other end surface 4b of the elastic covering material 4B is disposed in the middle portion 11d of the core metal body 11 in the axial direction A and is separated from the other end surface 11b of the core metal body 11. The other end surface 4b of the elastic covering material 4B may or may not face the air passage 3B. The air passage 3B is formed by a marking groove, and is open at the end surface 11a at one axial end side of the core metal body 11 and closed at the end surface 11b at the other axial end side of the core metal body 11. The length L of the air passage 3B is preferably at least 7 mm or more. The air passage 3B corresponds to a configuration in which the middle portion and the other end portion in the axial direction A are omitted from the air passage 3 of the embodiment, and therefore a detailed description thereof is omitted.

[0061] In the second modified example, in the press-fitting step, the other end surface 40b of the cylindrical material 40B, which is the material for the elastic covering material 4B, is disposed in the middle portion 11d of the core body 11. In this case, the portion (other end portion 40e) near the other end surface 40b of the cylindrical material 40B is fitted into the outer circumferential surface 11c of the core body 11, but no lugs are formed. Therefore, the other end portion 40e of the cylindrical material 40B is disposed so as not to hermetically close the gap between the cylindrical material 40B and the core body 11. In other words, in the configuration in which the other end portion 40e of the cylindrical material 40B is disposed in the middle portion 11d of the core body 11, the cylindrical material 40B does not hinder the flow of air between the other end portion 40e of the cylindrical material 40B and the core body 11. Therefore, even if there is no air passage 3B between the other end 40e of the cylindrical material 40B and the outer circumferential surface 11c of the core metal body 11, air existing between the other end 40e of the cylindrical material 40B and the core metal body 11 can be smoothly discharged. In addition, since the air passage 3B is disposed between the lug 41a formed at one end of the cylindrical material 40B and one end of the core metal body 11, air can also be smoothly discharged between the cylindrical material 40B and the core metal body 11 at one end face 11a of the core metal body 11. In addition, since it is necessary to form the air passage 3B only in a part of the axial direction of the core metal body 11, the time required for cutting and forming the air passage 3B can be further shortened.

[0062] (3) In the above-described embodiment and each modified example, the air passages 3, 3A, 3B are open to the outer circumferential surface 11c of the core metal body 11. However, this is not necessarily the case. For example, a tunnel-shaped air passage may be formed inside the core metal body 11, with one end of the air passage opening to the outer circumferential surface 11c of the core metal body 11 and the other end of the air passage opening to at least one of the end faces 11a, 11b of the core metal body 11. EXAMPLES

[0063] Elastic rollers were produced as Examples 1 to 8 and Comparative Examples 1 and 2. The manufacturing method for each Example is as follows. First, the cylindrical material was pressed into the core body by fitting the inner peripheral surface of the cylindrical material to the outer peripheral surface of the core body. At this time, the cylindrical material was attached to the core body while compressed air was blown from one end side of the cylindrical material. In this way, a manufacturing intermediate body was produced in which the cylindrical material was fitted to the outer peripheral surface of the core body. Next, a degassing process was performed on the manufacturing intermediate body. In the degassing process, the manufacturing intermediate body was left for several minutes. Next, both ends of the degassed cylindrical material of the manufacturing intermediate body were cut to make the entire length of the cylindrical material the same as the entire length of the core body, and this was used as the final manufacturing intermediate body. Next, the outer peripheral surface of the cylindrical material of this final manufacturing intermediate body was polished to make the outer diameter of the cylindrical material the same as the outer diameter of the coated elastic material. As a result, the cylindrical material became the elastic coating material, and the elastic roller was completed.

[0064] The first and second embodiments have a similar configuration to the elastic roller 1A shown in the first modified example, and the air passage has a first scribed groove and a second scribed groove. Examples 3 to 6 have the same configuration as the elastic roller 1 shown in the embodiment, and an air passage is formed over the entire axial area of ​​the core metal body. Examples 7 and 8 have a configuration similar to that of the elastic roller 1A shown in the first modified example, and the air passage has a first scribed groove and a second scribed groove. Comparative Examples 1 and 2 have the same configuration as the elastic roller 1 shown in the embodiment, except that no air passage is formed.

[0065] The width W, depth D, length L, and D / W, the value obtained by dividing the depth D by the width W, of each example are as shown in Table 1. The depth D and width W were measured using a VR-3000 manufactured by Keyence Corporation. The outer diameter of the core body, the overall length of the core body, and the hardness of the elastic covering material of each example were also measured. The hardness was measured by applying a load of 1 kg to the elastic roller using a durometer A hardness tester or an Asker C hardness tester.

[0066] [Table 1]

[0067] <Evaluation method> Each example was evaluated for air leakage, cutting position, and product runout.

[0068] The air escape was measured by measuring whether air remained between the cylindrical material and the core body in the final manufacturing intermediate. The measurement method was to hold the final manufacturing intermediate of Examples 1 to 8 and Comparative Examples 1 to 2 in the hand, and rotate the cylindrical material by hand relative to the core body while preventing the core body from rotating, and to confirm whether the cylindrical material moved (rotated) independently in the circumferential direction. The evaluation was performed by touch, and the degree of adhesion between the cylindrical material and the core body was confirmed. Specifically, when the cylindrical material did not rotate, it was deemed that the air escape was complete and was given an A rating. When it was determined by touch that the cylindrical material was rotating, it was deemed that air still remained and was given a B rating.

[0069] The cut position was measured by measuring how much the positions of both end faces of the cylindrical material in the axial direction A were misaligned from the target positions for cutting both end faces of the cylindrical material when the manufacturing intermediates of Examples 1 to 8 and Comparative Examples 1 and 2 were molded into the final manufacturing intermediates. A deviation of 0.5 mm or less was given an A rating, a deviation of 0.5 mm to 1.5 mm was given an B rating, and a deviation of more than 1.5 mm was given an C rating.

[0070] Regarding the product runout, the amount of runout of the outer circumferential surface of the elastic covering material was measured using a measuring machine while the end of the core bar of each example was placed on a bearing and rotated. The measuring machine used was a laser scan micro "LSM506S" manufactured by Mitutoyo Corporation. An image of the runout amount measurement result using the measuring machine is shown in FIG. 8. The horizontal axis of FIG. 8 indicates the measurement position in the axial direction of the core bar body, with one end face of the core bar body as the reference (zero mm position). The vertical axis of FIG. 8 indicates the amount of runout. In the amount of runout obtained by the measuring machine, if there is a portion that shows a particularly large value of the amount of runout as in the runout amount example 1 in the figure, this portion is defined as an abnormal runout portion. The abnormal runout portion is a portion where the amount of runout changes by 20% or more within a range of 200 mm of the measurement position. On the other hand, if there is no portion that shows a particularly large value of the amount of runout as in the runout amount example 2 in FIG. 8, there is no abnormal runout portion. The presence or absence of the abnormal runout portion is judged based on the rate of change of the runout amount, and is not influenced by the absolute value of the runout amount. The presence or absence of the abnormal runout portion was confirmed for Examples 1 to 8 and Comparative Examples 1 to 2. The cases where there was no abnormal runout portion were rated as A. The elastic roller rated A did not suffer from any defect due to air remaining between the core metal and the elastic covering material (cylindrical material) during the manufacturing process of the elastic roller, and was judged to have high runout accuracy as an elastic roller (small runout amount). The cases where there was an abnormal runout portion were rated as B. The elastic roller rated B suffered from a defect due to air remaining between the core metal and the elastic covering material (cylindrical material) during the manufacturing process of the elastic roller, which is considered to affect the runout accuracy of the elastic roller. Therefore, it was judged to have low dimensional accuracy as an elastic roller (large runout amount).

[0071] The results are shown in Table 1.

[0072] As shown in Table 1, in all of Examples 1 to 8, air leakage, cutting position, and product runout were all rated A due to the provision of air passages. In particular, in Examples 1 to 8, the width W of the air passage 3 was in the range of 0.1 mm to 2.2 mm, the depth D was in the range of 0.02 mm to 0.50 mm, and the value D / W obtained by dividing the depth D by the width W was 0.03 or more. As a result, air leakage, cutting position, and product runout were all rated A. On the other hand, in both Comparative Examples 1 and 2, no air passage was provided regardless of whether the outer diameter of the core was large or small, and regardless of whether the overall length of the core body was long or short. As a result, air leakage, cutting position, and product runout were all rated the lowest, and the adverse effect of poor air leakage between the cylindrical material and the core body occurred.

[0073] As is clear from the evaluation results of Examples 1 to 8 and Comparative Examples 1 and 2, the provision of open air passages on both the outer peripheral surface and the end face of the core bar body makes it possible to effectively exhaust the air existing between the elastic covering material and the core bar body, thereby demonstrating that it is possible to suppress the occurrence of problems caused by air remaining between the core bar and the elastic covering material (the cylindrical material from which the elastic covering material is made). [Industrial Applicability]

[0074] The present invention is applicable to a core bar, an elastic roller, and a method for manufacturing an elastic roller. [Explanation of symbols]

[0075] 1 Elastic roller 2 Core wire 3,3A,3B Air passage 4,4B Elastic covering material 11 Core body 11a, 11b End surface of the core body 11c Outer surface of the core body 12a,12b Core metal end 31 First marking groove 32 Second marking groove A axis direction D Depth of scribed groove L Length of the marking groove W Width of the marking groove

Claims

1. A core bar for an elastic roller, A shaft-shaped core body, an air passage opening to both an outer circumferential surface of the core body and an end surface of the core body; Equipped with The air passage includes a groove extending along an axial direction of the outer circumferential surface, The marking grooves include a first marking groove that is open on an end face on one axial end side of the core metal body and formed in a portion of the axial direction of the core metal body, and a second marking groove that is open on an end face on the other axial end side of the core metal body and formed in a portion of the axial direction of the core metal body, The scribe groove is not formed in the axial center of the core body, and the first scribe groove and the second scribe groove are spaced apart from each other.

2. A core bar for an elastic roller, A shaft-shaped core body, an air passage opening to both an outer circumferential surface of the core body and an end surface of the core body; Equipped with The air passage includes a groove extending along an axial direction of the outer circumferential surface, A core bar, wherein, when viewed from the axial direction of the core bar, the width of the scribed groove is 0.1 mm to 2.2 mm, the depth of the scribed groove is 0.02 mm to 0.50 mm, and the value obtained by dividing the depth by the width is 0.03 or more.

3. The core bar according to claim 2 , wherein the scribe groove is formed over the entire axial area of ​​the core bar body.

4. 3. The core bar according to claim 2, wherein the scribed groove is open on one axial end face of the core bar body and closed on the other axial end face of the core bar body.

5. The core bar according to any one of claims 1 to 4, wherein the length of the scribe groove in the axial direction of the core bar body is 7 mm or more.

6. The core according to any one of claims 1 to 5, further comprising a core end portion protruding from an axial end face of the core body and having an outer diameter smaller than an outer diameter of the core body.

7. A hollow elastic covering material; An elastic roller comprising: the core metal according to any one of claims 1 to 6, the core metal body being fitted with the elastic covering material.

8. A preparation step of preparing a hollow elastic covering material and a core bar according to any one of claims 1 to 6; a press-fitting step of press-fitting the elastic covering material onto the core by fitting an inner peripheral surface of the elastic covering material onto an outer peripheral surface of the core body; a deaeration step of discharging air between the core bar and the elastic covering material through the air passage; The method for manufacturing an elastic roller includes the steps of:

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