Method for manufacturing a roller shaft

Abstract

To provide a roller shaft where a resin body is fixed to a long shaft body, which can achieve reduction of cost as much as possible while securing fixing strength to the shaft body of the resin body.SOLUTION: A roller shaft includes a long shaft body and a resin body fixed to a prescribed position in an axial direction having the same diameter as the shaft body, wherein the resin body integrally has a body part having prescribed thickness, and an extension part which is adjacent to the body part in the axial direction of the shaft body, and has a smaller diameter than the body part by being set to be thinner than the body part.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a roller shaft suitably used in a sheet conveying mechanism in a printer, a facsimile machine, or the like. Manufacturing method It relates thereto.

Background Art

[0002] A structure in which a star wheel (pulsator) and a roller shaft are arranged opposite to each other so as to sandwich a sheet such as paper to be conveyed, and the sheet is pinched and conveyed by the star wheel and the roller shaft is used in a conveying mechanism in OA equipment such as a printer and a facsimile machine, for example.

[0003] The roller shaft and the star wheel are arranged on the downstream side in the sheet conveying direction from a recording means such as an inkjet head, and it is necessary to convey the sheet while preventing the transfer of the ink printed on the sheet by the recording means as much as possible.

[0004] In this regard, a stepped roller shaft including a shaft body and a plurality of rubber rings press-fitted into the shaft body has been proposed (see Patent Document 1 below). Specifically, a plurality of star wheels are arranged at intervals along the width direction of the sheet on one side in the thickness direction of the sheet. On the other hand, the stepped roller shaft is arranged on the other side in the thickness direction of the sheet, and the plurality of rubber rings are press-fitted into the shaft body so as to face each of the plurality of star wheels. With such a configuration, the corresponding rubber ring and the star wheel pinch and convey the sheet.

[0005] This stepped roller shaft can substantially limit the area in contact with the sheet to only the rubber ring, and thus it is useful in that it can prevent the ink printed on the sheet from transferring to the roller shaft as much as possible. However, the rubber ring must be press-fitted into a predetermined position of the shaft body so as to face the star wheel, and it is difficult to efficiently manufacture the roller shaft, resulting in a problem of high manufacturing cost. In addition, since the rubber ring is fixed to the shaft body by press-fitting, there is also a problem that it is difficult to maintain the fixing strength of the rubber ring to the shaft body.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] The present invention has been made in view of the above prior art, and is a roller shaft in which a resin body is fixed to the outer surface of a long shaft body, and can achieve cost reduction as much as possible while ensuring the fixing strength of the resin body to the shaft body. Manufacturing method The purpose is to provide.

Means for Solving the Problems

[0008] In order to achieve the above object, the present invention provides a long shaft body and a resin body fixed to the same diameter of the shaft body. Part to In a state of being spaced apart in the axial direction fixed A plurality of A roller shaft having a resin body, wherein the A plurality of resin body Each of is The length along the axial direction of the shaft body is L and the thickness is T an integral body having a main body portion and an extending portion that is adjacent to the main body portion in the axial direction of the shaft body and has a smaller diameter than the main body portion by having a thickness thinner than that of the main body portion. A manufacturing method, comprising: while rotating the shaft body about its axis, applying a molten hot melt resin to a plurality of resin body forming regions on the outer surface of the shaft body where the plurality of resin bodies are provided such that the axial length La is shorter than L and the thickness Ta is thicker than T; a plurality of molding rolls having a small diameter portion with an axial length of L and a cross-sectional shape of a circle with a predetermined diameter, a large diameter portion with a cross-sectional shape of a circle larger in diameter than the small diameter portion, concentric with the small diameter portion and adjacent to the small diameter portion in the axial direction, and a support shaft that supports the small diameter portion and the large diameter portion on the central axis, the plurality of molding rolls for molding the plurality of resin bodies respectively; and a plurality of housings that rotatably support the plurality of molding rolls about their axes, and by moving the plurality of molding rolls in a direction approaching the shaft body rotating about its axis in a parallel posture with the shaft body and positioning them at a predetermined molding position, a molding step of molding the hot melt resin applied to the plurality of resin body forming regions is provided. The housing has a pair of side walls that respectively support one end and the other end of the support shaft of the corresponding molding roll, and a base end wall that connects the base end portions of the pair of side walls, and is U-shaped in plan view with the free end side, the upper side, and the lower side facing the shaft body being open. The molding position is a position where the separation distance between the outer surface of the small diameter portion and the outer surface of the shaft body is T. By positioning the molding roll at the molding position, a molding space with a thickness of T and an axial length of L and open upper and lower sides is formed between the outer surface of the small diameter portion and the outer surface of the shaft body. Further, a receiving space with a thickness of Ts thinner than T and open upper and lower sides and communicating with the molding space is formed between the outer surface of the large diameter portion and the outer surface of the shaft body. The axial length La and the thickness Ta of the hot melt resin applied in the coating step are set such that when the molding roll is positioned at the molding position, the molding space is filled with the hot melt resin and the excess that protrudes from the molding space flows into the receiving space. Manufacturing method of roller shaft is provided.

[0009] Preferably, the The pair of side walls have a vertical length greater than the diameter of the shaft body. An arc-shaped notch opening towards the side of the shaft body is provided on the front end surfaces of the pair of side walls. When the forming roll is positioned at the forming position, a part of the shaft body is positioned within the arc-shaped notch in a state where a gap smaller than Ts exists between the outer surface of the arc-shaped notch and the outer surface of the shaft body is.

Effects of the Invention

[0010] According to the roller shaft according to the present invention Manufacturing method It is possible to achieve cost reduction as much as possible while ensuring the fixing strength of the resin body to the shaft body.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

Embodiments for Carrying Out the Invention

[0012] Embodiment 1 Hereinafter, a preferred embodiment of a roller shaft according to the present invention will be described with reference to the accompanying drawings. Fig. 1 shows a schematic diagram of an example of a conveying mechanism 1 for conveying a sheet body such as paper to which a roller shaft 10 according to the present embodiment is applied.

[0013] The conveying mechanism 1 has one or a plurality of star wheels 3 arranged on one side in the thickness direction of the sheet body, and the roller shaft 10 arranged on the other side in the thickness direction of the sheet body so as to correspond to the star wheel 3 with the sheet body interposed therebetween, and the roller shaft 10 is configured to cooperate with the star wheel 3 to sandwich and convey the sheet body.

[0014] In the conveying mechanism shown in FIG. 1, the roller shaft 10 is disposed on the downstream side in the conveying direction of the sheet body from the inkjet head 2, and is used to discharge the printed sheet body in cooperation with the star wheel 3. In addition, the reference numerals 4 and 5 in FIG. 1 are a paper feed roller and a separation roller, respectively. Further, the reference numerals 6 and 7 are a pinch roller and a paper feed roller, respectively.

[0015] FIG. 2(a) shows a plan view of the roller shaft 10. Further, FIG. 2(b) shows a cross-sectional view taken along line IIb-IIb in FIG. 2(a). Further, FIG. 3(a) shows an enlarged view of a portion III in FIG. 2(b). Furthermore, FIGS. 3(b) and (c) show cross-sectional views taken along lines IIIb-IIIb and IIIc-IIIc in FIG. 3(a), respectively.

[0016] As shown in FIGS. 2 and 3, the roller shaft 10 has a rigid shaft body 20 and a resin body 30 fixed to a predetermined position in the axial direction of the shaft body 20.

[0017] The shaft body 20 can be formed of various materials as long as it has a predetermined rigidity, but is preferably formed of a metal material such as steel. In addition, the shaft body 20 can take either a solid or a hollow form.

[0018] The resin body 30 is provided at a predetermined position in the axial direction of the shaft body 20. For example, when the roller shaft 10 is used in the conveying device 1 so as to cooperate with the star wheel 3, the resin body 30 is provided at the same position as the star wheel 3 with respect to the axial position of the shaft body 20.

[0019] The roller shaft 10 is configured to have one or a plurality of desired numbers of the resin bodies 30 according to requirements or specifications. In FIG. 2, the roller shaft 10 has five resin bodies 30.

[0020] As shown in FIG. 3, the resin body 30 integrally has a main body portion 31 having an axial length L and a thickness T, and an extending portion 33 having a thickness Ts thinner than the main body portion 31 and adjacent to the main body portion 31 in the axial direction of the shaft body 20.

[0021] When the roller shaft 10 is used in the conveying device 1 together with the star wheel 3, the main body portion 31 of the resin body 30 cooperates with the corresponding star wheel 3 to convey the sheet body.

[0022] That is, the star wheel 3 is arranged such that the outer peripheral surface abuts against a first surface (for example, the upper surface) on one side in the thickness direction of the sheet body with the axial direction along the width direction of the sheet body.

[0023] On the other hand, the roller shaft 10 is arranged such that the outer peripheral surface of the main body portion 31 abuts against a second surface (for example, the lower surface) on the other side in the thickness direction of the sheet body with the axial direction of the shaft body 20 along the width direction of the sheet body.

[0024] Thereby, the sheet body is sandwiched between the star wheel 3 and the main body portion 31 and conveyed in response to the rotational drive around the axis of the star wheel 3.

[0025] At this time, the roller shaft 10 is driven to rotate passively around the axis by the frictional force between the conveyed sheet body and the outer peripheral surface of the main body portion 31 in contact with the sheet body.

[0026] Therefore, in order to smoothly convey the sheet body, · The main body portion 31 of the resin body 30 is firmly fixed to the shaft body 20 at a predetermined position in the axial direction. · The main body portion 31 has a predetermined axial length L and thickness T so that a desired frictional force can be obtained between the sheet body and the main body portion 31. is important.

[0027] Regarding this point, in the present embodiment, as shown in FIGS. 3(a) to 3(c) and the like, in addition to the main body portion 31 having the axial length L and the thickness T that abuts against the sheet body, the resin body 30 is adjacent to the main body portion 31 in the axial direction of the shaft body 20 and has an extending portion 33 with a thickness Ts that is thinner than the main body portion 31.

[0028] According to the resin body 30 having such a configuration, while the dimensions of the portion in contact with the sheet body (i.e., the main body portion 31) are set to desired dimensions (i.e., the axial length L and the thickness T), the contact area with the shaft body 20 can be enlarged, and the fixing strength of the resin body 30 to the shaft body 20 can be increased.

[0029] In particular, in the present embodiment, as shown in FIG. 3(a), the extending portion 33 has first and second extending portions 33a and 33b provided on one side and the other side of the main body portion 31 in the axial direction of the shaft body 20, respectively, and it is possible to further increase the fixing strength of the resin body 30 to the shaft body 20.

[0030] The resin body 30 can be fixed to the shaft body by various means such as an adhesive or welding. However, in the present embodiment, the resin body 30 is formed of a thermoplastic resin (hot melt resin) and is fixed to the shaft body 20 by welding.

[0031] Hereinafter, an example of a manufacturing method of the roller shaft 10 according to the present embodiment (hereinafter referred to as the first manufacturing method) will be described. FIG. 4 shows a schematic plan view of the initial state of a manufacturing apparatus used by the first manufacturing method.

[0032] The first manufacturing method has a coating step of applying a hot melt resin 40 in a molten state by heating to a resin body forming region 25 (see FIGS. 4 and 5 below) on the outer surface of the shaft body 20 where the resin body 30 is provided, with an axial length La shorter than L and a thickness Ta thicker than T, while rotating the shaft body 20 around its axis.

[0033] Fig. 5 shows a schematic plan view of the manufacturing apparatus after the coating step. In the example shown in Fig. 5, a state where the hot-melt resin 40 is applied to five resin body forming regions 25 is shown.

[0034] The rotation of the shaft body 20 around its axis is performed by a rotation drive mechanism (not shown), and the application of the hot-melt resin 40 is performed by a resin discharge mechanism (not shown).

[0035] The hot-melt resin 40 is required to have a viscosity such that it does not detach from the shaft body 20 rotated around the axis when applied to the outer surface of the shaft body 20 in a heated and melted state. For example, polyolefin resins, polyurethane resins, etc. are preferably used.

[0036] The first manufacturing method includes a molding step of molding the hot-melt resin 40 applied to the resin body forming region 25 using a molding roll 50.

[0037] Fig. 6 shows a schematic plan view of the manufacturing apparatus in a state where the molding roll 50 is positioned at the molding position. Fig. 7 shows an enlarged view of part VII in Fig. 6. Also, Figs. 8(a) to 8(c) show cross-sectional views along lines VIIIa-VIIIa, VIIIb-VIIIb, and VIIIc-VIIIc in Fig. 7, respectively.

[0038] The first manufacturing method uses one molding roll 50 for each resin body forming region 25. As described above, in the examples shown in Figs. 5 and 6, five resin body forming regions 25 are provided, and thus, five corresponding molding rolls 50 are used.

[0039] As shown in FIGS. 7 and 8(a) to (c), the molding roll 50 has a small-diameter portion 51 with an axial length of L and a circular cross-sectional shape having a predetermined diameter, and a large-diameter portion 53 with a circular cross-sectional shape having a larger diameter than that of the small-diameter portion 51, which is concentric with the small-diameter portion 51 and adjacent to the small-diameter portion 51 in the axial direction.

[0040] The small-diameter portion 51 molds the main body portion 31, and the large-diameter portion 53 molds the extending portion 33. As described above, in the present embodiment, the extending portion 33 has first and second extending portions 33a and 33b that extend from the main body portion 31 in one axial direction and the other axial direction, respectively. Therefore, the molding roll 50 has first and second large-diameter portions 53a and 53b that extend from the small-diameter portion 51 in one axial direction and the other axial direction, respectively, as the large-diameter portion 53.

[0041] The molding step is configured to mold the hot-melt resin 40 applied to the resin body forming region 25 of the shaft body 20 into the final shape of the resin body 30 by moving the molding roll 50 in a direction close to the shaft body 20 that is rotated about its axis in a parallel posture to the shaft body 20 to the molding position.

[0042] The molding position is set to a position where the separation distance between the outer surface of the small-diameter portion 51 and the outer surface of the shaft body 20 is the thickness T of the main body portion 31. As shown in FIG. 7, by positioning the molding roll 50 at the molding position, a molding space 41 with a thickness of T and an axial length of L is formed between the outer surface of the small-diameter portion 51 and the outer surface of the shaft body 20. Further, a receiving space 43 with a thickness of Ts thinner than T and communicating with the molding space 41 is formed between the outer surface of the large-diameter portion 53 and the outer surface of the shaft body 20.

[0043] In the coating step, the axial length La and the thickness Ta of the hot melt resin 40 (see FIG. 5) applied are set to values such that when the molding roll 50 is positioned at the molding position, the molding space 41 is filled with the hot melt resin 40 and the surplus protruding from the molding space 41 flows into the receiving space 43.

[0044] According to the first manufacturing method having such a configuration, the roller shaft 10 in which the resin body 30 including the main body portion 31 and the extending portion 33 is fixed to a predetermined region (the resin body forming region 25) of the shaft body 20 can be efficiently manufactured.

[0045] As shown in FIG. 5 and the like, in the first manufacturing method, the molding step is configured to be performed using a housing 60 that rotatably supports the molding roll 50 about the axis so that the small diameter portion 51 and the large diameter portion 53 can rotate about the axis, and a reciprocating molding mechanism 70 that moves the housing 60 toward and away from the shaft body 20.

[0046] As shown in FIGS. 7 and 8(a) to (c), the molding roll 50 has a support shaft 55 that supports the small diameter portion 51 and the large diameter portion 53 on the central axis.

[0047] The housing 60 has a pair of side walls 61 that respectively support one end portion and the other end portion of the support shaft 55 in a posture parallel to the shaft body 20, and is configured to allow access to the small diameter portion 51 and the large diameter portion 53 from the side of the shaft body 20.

[0048] In the first manufacturing method, in addition to the pair of side walls 61, the housing 60 has a base end wall 63 that connects the base end portions of the pair of side walls 61, and is substantially U-shaped in plan view with the free end side, the upper side, and the lower side facing the shaft body 20 being open.

[0049] In the present embodiment, the support shaft 55 is configured to rotate integrally about the axis together with the small-diameter portion 51 and the large-diameter portion 53. By rotatably supporting the support shaft 55 about the axis on the pair of side walls 61, the small-diameter portion 51 and the large-diameter portion 53 are rotatable about the axis with respect to the housing 60.

[0050] Alternatively, it is also possible to deform such that the support shaft 55 rotatably supports the small-diameter portion 51 and the large-diameter portion 53, and the pair of side walls 61 non-rotatably supports the support shaft 55 about the axis.

[0051] The reciprocating mechanism 70 for molding has a piston mechanism that moves the housing 60 closer to and away from the shaft body 20 so that the molding roll 50 can take a molding position (see FIG. 6) and a retracted position (see FIG. 5) spaced apart from the shaft body 20 from the molding position.

[0052] As shown in FIG. 8(c), in the present embodiment, the pair of side walls 61 has an up-down direction length H that is larger than the diameter D of the shaft body 20. Further, an arc-shaped notch 62 that opens toward the side of the shaft body is provided on the front end surfaces of the pair of side walls 61.

[0053] As shown in FIG. 8(c), when the molding roll 50 is positioned at the molding position, a part of the shaft body 20 is positioned within the arc-shaped notch 62 in a state where a gap smaller than Ts exists between the outer surface of the arc-shaped notch 62 and the outer surface of the shaft body 20.

[0054] According to such a configuration, in the molding step, it is possible to effectively prevent or reduce the hot melt resin flowing from the molding space 41 into the receiving space 43 from leaking outward in the axial direction from the receiving space 43.

[0055] Preferably, when the molding reciprocating mechanism 70 positions the molding roll 50 at the molding position, the non-resin body region 27 (see FIG. 4) of the shaft body 20 other than the resin body forming region 25 in the axial direction is pressed in a direction opposite to the pressing direction by the molding reciprocating mechanism 70.

[0056] According to such a configuration, the "flexure" of the shaft body 20 that may occur when the molding reciprocating mechanism 70 presses the molding roll 50 toward the shaft body 20 can be effectively prevented or reduced.

[0057] In the present embodiment, as shown in FIG. 6 and the like, the pressing of the non-resin body region 27 in a direction opposite to the pressing direction by the molding reciprocating mechanism 70 is performed by a pressure-resistant reciprocating mechanism 75 configured to reciprocate a pressing rod 77 whose axial direction is parallel to the pressing direction of the molding reciprocating mechanism 70 along the axial direction.

[0058] The first manufacturing method preferably may include a cooling step of cooling the hot melt resin 40 on the shaft body 20 after the coating step and before the molding step. The cooling step is configured to cool the hot melt resin 40 on the shaft body 20 within a range until it reaches complete curing (that is, within a range maintaining a semi-cured state enabling the molding process in the subsequent molding step).

[0059] The cooling step is configured to, for example, spray water on the hot melt resin 40 on the shaft body 20. According to such a configuration, during the molding step, the adhesion of the hot melt resin to the molding roll 50 can be effectively prevented or reduced, and the molding processability (outer diameter dimension and roundness) can be improved.

[0060] More preferably, the cooling step is configured to spray water on the hot melt resin 40 by a sprayer. According to such a configuration, the adhesion of water to the outer surface of the hot melt resin 40 can be improved.

[0061] Further, preferably, a mold release material can be provided on the outer surfaces of the small-diameter portion 51 and the large-diameter portion 53 of the molding roll 50. The mold release material is, for example, oil, silicone resin, or fluororesin. Oil or silicone is provided on the outer surface, for example, by applying it to the outer surfaces of the small-diameter portion 51 and the large-diameter portion 53 of the molding roll 50 before the molding step. Fluororesin is provided on the outer surface, for example, by applying fluororesin to the outer surfaces of the small-diameter portion 51 and the large-diameter portion 53 when manufacturing the molding roll 50, and preferably by baking.

[0062] Hereinafter, another example of the manufacturing method of the roller shaft 10 according to the present embodiment (hereinafter referred to as the second manufacturing method) will be described. FIG. 9 shows a schematic plan view of a manufacturing apparatus used by the second manufacturing method.

[0063] The first manufacturing method is configured to perform molding of a hot-melt resin using one molding roll 50 for each resin body formation region 25. In contrast, the second manufacturing method is configured to perform molding of the hot-melt resin 40 using a pair of molding rolls including a first and a second molding roll 50-(1), 50-(2) for each resin body formation region 25.

[0064] Specifically, the second manufacturing method has the same coating step as in the first manufacturing method. FIG. 9 shows the state after the coating step.

[0065] The second manufacturing method has a molding step of performing molding of the hot-melt resin 40 using the pair of molding rolls provided for each resin body formation region 25 after the coating step.

[0066] In the example shown in FIG. 9, five resin body formation regions are provided, and accordingly, five pairs of molding rolls corresponding thereto are used.

[0067] The first and second forming rolls 50-(1) and 50-(2) of the pair of forming rolls have the same configuration as the forming roll 50 used in the first manufacturing method. That is, each of the first and second forming rolls 50-(1) and 50-(2) has the small-diameter portion 51 and the large-diameter portion 53 (the first and second large-diameter portions 53a and 53b in the illustrated example).

[0068] In the forming step in the second manufacturing method, the first forming roll 50-(1) is translated to the first forming position in a direction approaching the rotatable shaft body 20 while being arranged parallel to the shaft body 20 on one side of the virtual vertical plane VP passing through the axis of the shaft body 20, and the second forming roll 50-(2), which is symmetric with the first forming roll 50-(1) with respect to the virtual vertical plane VP, is translated to the second forming position in a direction approaching the rotatable shaft body 20 while being arranged parallel to the shaft body 20 on the other side of the virtual vertical plane VP, thereby forming the hot-melt resin 40 applied to the resin body forming region 25.

[0069] FIG. 10 shows a schematic plan view of the manufacturing apparatus in a state where the first forming roll 50-(1) is located at the first forming position and the second forming roll 50-(2) is located at the second forming position. FIG. 11 shows an enlarged view of part XI in FIG. 10. Also, FIGS. 12(a) to 12(c) show cross-sectional views taken along lines XIIa-XIIa, XIIb-XIIb, and XIIc-XIIc in FIG. 11, respectively.

[0070] As shown in FIGS. 11 and 12(a) to 12(c), the first forming position is a position where the separation distance between the outer surface of the small-diameter portion 51 of the first forming roll 50-(1) and the outer surface of the shaft body 20 is T.

[0071] By positioning the first molding roll 50-(1) at the first molding position, a first molding space 41-(1) with a thickness of T and an axial length of L is formed between the small-diameter portion 51 of the first molding roll 50-(1) and the outer surface of the shaft body 20. Further, a first receiving space 43-(1) with a thickness of Ts, which is thinner than T, and communicating with the first molding space 41-(1) is formed between the outer surface of the large-diameter portion 53 of the first molding roll 50-(1) and the outer surface of the shaft body 20.

[0072] The second molding position is a position where the separation distance between the outer surface of the small-diameter portion 51 of the second molding roll 50-(2) and the outer surface of the shaft body 20 is T.

[0073] By positioning the second molding roll 50-(2) at the second molding position, a second molding space 41-(2) with a thickness of T and an axial length of L is formed between the small-diameter portion 51 of the second molding roll 50-(2) and the outer surface of the shaft body 20. Further, a second receiving space 41-(3) with a thickness of Ts, which is thinner than T, and communicating with the second molding space 41-(2) is formed between the outer surface of the large-diameter portion 53 of the second molding roll 50-(2) and the outer surface of the shaft body 20.

[0074] As shown in FIG. 9 and the like, in the second manufacturing method, a first housing 60-(1) that supports the first molding roll 50-(1) so that the small-diameter portion 51 and the large-diameter portion 53 of the first molding roll 50-(1) are rotatable about the axis, a first reciprocating mechanism 70-(1) that moves the first housing 60-(1) toward and away from the shaft body 20, a second housing 60-(2) that supports the second molding roll 50-(2) so that the small-diameter portion 51 and the large-diameter portion 53 of the second molding roll 50-(2) are rotatable about the axis, and a second reciprocating mechanism 70-(2) that moves the second housing 60-(2) toward and away from the shaft body 20 are used.

[0075] As shown in FIGS. 11 and 12(a) to (c), each of the first and second molding rolls 50-(1) and 50-(2) has a support shaft 55 that supports the small-diameter portion 51 and the large-diameter portion 53 on the central axis.

[0076] The first and second housings 60-(1) and 60-(2) have the same configuration as the housing 60.

[0077] Also, the first and second reciprocating mechanisms 70-(1) and 70-(2) for molding have the same configuration as the reciprocating mechanism 70 for molding.

[0078] In the second manufacturing method, during the molding step, the shaft body 20 will be narrowly pressed by the first and second molding rolls 50-(1) and 50-(2). Therefore, without providing the pressure-resistant reciprocating mechanism 75, the "bending" of the shaft body 20 that occurs during the molding step can be effectively prevented or reduced.

[0079] Also in the second manufacturing method, similar to the first manufacturing method, the cooling step can be provided after the coating step and before the molding step, and the release material can be provided on the outer surfaces of the small-diameter portion 51 and the large-diameter portion 53 of the first and second molding rolls 50-(1) and 50-(2).

[0080] Embodiment 2 Hereinafter, other preferred embodiments of the roller shaft according to the present invention will be described with reference to the accompanying drawings.

[0081] FIG. 13(a) shows a plan view of a roller shaft 110 according to the present embodiment. Also, FIG. 13(b) shows a cross-sectional view taken along line XIIIb-XIIIb in FIG. 13(a). Also, FIG. 14(a) shows an enlarged view of part XVI in FIG. 13(b). Furthermore, FIG. 14(b) shows a cross-sectional view taken along line XIVb-XIVb in FIG. 14(a). In the drawings, the same members as those in the first embodiment are denoted by the same reference numerals.

[0082] The roller shaft 110 has the shaft body 20 and a resin body 130 fixed to a predetermined position in the axial direction of the shaft body 20.

[0083] As shown in FIGS. 13 and 14, a recess 133 is provided over the entire circumference at an intermediate position in the axial direction of the shaft body 20 on the outer surface of the resin body 130.

[0084] Hereinafter, an example of a method for manufacturing the roller shaft 110 according to the present embodiment (hereinafter referred to as the third manufacturing method) will be described.

[0085] The third manufacturing method has a coating step of applying a hot melt resin 40 in a molten state by heating to a resin body forming region 25 on the outer surface of the shaft body 20 where the resin body 130 is provided while rotating the shaft body 20 around its axis so that the axial length Lc is shorter than L and the thickness Tc is thicker than T.

[0086] FIG. 15 shows a schematic plan view of a manufacturing apparatus used by the third manufacturing method, which is a schematic plan view of the state after the coating step.

[0087] The third manufacturing method has an intermediate molding step of performing intermediate molding on the hot melt resin 40 applied to the resin body forming region 25 after the coating step. The intermediate molding step is performed using an intermediate molding roll 150.

[0088] FIG. 16 shows a schematic plan view of the manufacturing apparatus in a state where the intermediate molding roll 150 is positioned at the intermediate molding position. Further, FIG. 17 shows an enlarged view of part XVII in FIG. 16. In FIG. 17, the hot melt resin 40 in the state after the coating step and before the intermediate molding step is shown by a two-dot chain line.

[0089] As shown in FIGS. 15 and 16, the intermediate forming roll 150 is provided for each resin body forming region 25. In the example shown in FIGS. 15 and 16, five resin body forming regions 25 are provided, and accordingly, five intermediate forming rolls 150 corresponding thereto are used.

[0090] As shown in FIG. 17 and the like, the intermediate forming roll 150 has an intermediate cylindrical portion 151 having a circular cross-sectional shape with a predetermined diameter and an intermediate support shaft 155 that supports the intermediate cylindrical portion 151 on the central axis, and the intermediate cylindrical portion 151 has a convex portion 153 that protrudes radially outward at an intermediate position in the axial direction on the outer peripheral surface.

[0091] In the intermediate forming step, the intermediate forming roll 150 is rotated about the axis in a posture parallel to the shaft body 20 and moved in a direction approaching the shaft body 20 to an intermediate forming position where the separation distance Td between the outer surface of the intermediate cylindrical portion 151 and the outer surface of the shaft body 20 is smaller than Tc and larger than T, so that a recess 43 is formed in the outer surface of the hot melt resin 40 applied to the resin body forming region 25 by the convex portion 153.

[0092] In the third manufacturing method, the intermediate forming step is configured to be performed using an intermediate housing 160 that supports the intermediate forming roll 150 and a forming reciprocating mechanism 70 that moves the intermediate housing 160 toward and away from the shaft body 20.

[0093] The intermediate housing 160 has a pair of intermediate side walls 161 that respectively support one end portion and the other end portion of the intermediate support shaft 155 in a posture parallel to the shaft body 20, and is configured to allow access from the side of the shaft body 20 to the intermediate cylindrical portion 151.

[0094] In the third manufacturing method, the intermediate housing 160 has, in addition to the pair of intermediate side walls 161, an intermediate base end wall 163 that connects the base end portions of the pair of intermediate side walls 161, and is substantially U-shaped in plan view with the free end side, upper side, and lower side facing the shaft body 20 being open.

[0095] The intermediate reciprocating mechanism 160 has a piston mechanism that moves the intermediate housing 160 toward and away from the shaft body 20 so that the intermediate molding roll 150 can take an intermediate molding position (FIG. 16) and a retracted position (FIG. 15) spaced apart from the shaft body 20 from the intermediate molding position.

[0096] The third manufacturing method has a final molding step of performing final molding on the hot melt resin 40 on the resin body formation region 25 after the intermediate molding step. The final molding step is performed using a final molding roll 170.

[0097] FIG. 18 shows a schematic plan view of the manufacturing apparatus in a state where the final molding roll 170 is positioned at the final molding position. FIG. 19 shows an enlarged view of portion XIX in FIG. 18. In FIG. 19, the hot melt resin 40 in a state after the intermediate molding step and before the final molding is indicated by a two-dot chain line. Furthermore, FIGS. 20(a) and (b) show cross-sectional views taken along lines XXa-XXa and XXb-XXb in FIG. 19, respectively.

[0098] As shown in FIG. 18, the final molding roll 170 is provided for each resin body formation region 25. In the example shown in FIG. 18, five resin body formation regions 25 are provided, and accordingly, five final molding rolls 170 corresponding thereto are used.

[0099] As shown in FIG. 19 and the like, the final molding roll 170 has a final cylindrical portion 171 having a circular cross-sectional shape with a predetermined diameter and a final support shaft 175 that supports the final cylindrical portion 171 on the central axis. The final cylindrical portion 171 has the same length as the axial length L of the resin body 130.

[0100] In the final molding step, the final molding roll 170 is rotated about the axis in a parallel posture to the shaft body 20 in a direction approaching the shaft body 20, and the separation distance between the outer surface of the final cylindrical portion 171 and the outer surface of the shaft body 20 is moved to the final molding position where it becomes T, so that the hot melt resin 40 after the intermediate molding step is molded into the resin body 130 having an axial length of L and a thickness of T.

[0101] In the third manufacturing method, the axial length Lc and the thickness Tc of the hot melt resin 40 applied in the coating step are such that when the final molding roll 170 is positioned at the final molding position, the molding space having an axial length of L and a thickness of T defined by the outer surface of the final cylindrical portion 171 and the outer surface of the shaft body 20 is filled with the hot melt resin 40.

[0102] Here, the coating amount error of the hot melt resin in the coating step is effectively absorbed by the recess 43. That is, when the coating amount of the hot melt resin applied in the coating step exceeds the amount for filling the molding space (molding space filling amount), the recess 43 is filled by the excess amount. Therefore, as the excess amount of the hot melt resin in the coating step increases with respect to the molding space filling amount, the recess 133 becomes smaller with respect to the recess 43.

[0103] As shown in FIG. 19 and the like, in the third manufacturing method, the final molding step is performed using a final housing 180 that supports the final molding roll 170 so that the final cylindrical portion 171 can rotate freely about the axis.

[0104] The final housing 180 has a pair of final side walls 181 that support one side and the other side of the final support shaft 175 in a state of being adjacent to one axial end side and the other axial end side of the final cylindrical portion 171, respectively, and is configured to allow access from the side of the shaft body 20 to the final cylindrical portion 171.

[0105] In the third manufacturing method, in addition to the pair of final side walls 181, the final housing 180 has a final base end wall 183 that connects the base end portions of the pair of final side walls 181, and is substantially U-shaped in plan view with the free end side, upper side, and lower side facing the shaft body 20 being released.

[0106] In the third manufacturing method, as shown in FIGS. 16 and 18 and the like, the intermediate molding step and the final molding step are configured to be performed using the reciprocating molding mechanism 70.

[0107] Furthermore, in the third manufacturing method, when the intermediate molding roll 150 and the final molding roll 170 are positioned at the intermediate molding position and the final molding position, respectively, by the reciprocating molding mechanism 70 in the intermediate molding step and the final molding step, the non-resin body region 27 of the shaft body 20 other than the resin body forming region 25 in the axial direction is configured to be pressed in a direction opposite to the pressing direction by the reciprocating molding mechanism 70.

[0108] As shown in FIGS. 16 and 18 and the like, the pressing of the non-resin body region 27 in a direction opposite to the pressing direction by the reciprocating molding mechanism 70 is performed by the pressure-resistant reciprocating mechanism 75.

[0109] In addition, instead of pressing the non-resin body region 27 of the shaft body 20 in a direction opposite to the pressing direction by the reciprocating molding mechanism 70 during the intermediate molding step and the final molding step, it is also possible to provide a pair of the intermediate molding rolls 150 and a pair of the final molding rolls 170 that face each other with the shaft body 20 interposed therebetween for each resin body forming region 25.

[0110] That is, the hot-melt resin 40 applied to the resin body formation region 25 is narrowly pressed by the pair of intermediate molding rolls 150 to perform intermediate molding, and the hot-melt resin 40 after intermediate molding is narrowly pressed by the pair of final molding rolls 170 to perform final molding. Thereby, the "bending" of the shaft body 20 during the intermediate molding process and the final molding process can be effectively prevented or reduced.

[0111] Preferably, the third manufacturing method can include the same cooling process as the cooling process in the first and second manufacturing methods after the coating process and before the intermediate molding process, and / or after the intermediate molding process and before the final process. Also, the mold release material can be provided on the outer surface of the intermediate cylindrical portion 151 and / or the final cylindrical portion 171.

Explanation of Reference Numerals

[0112] 10 Roller shaft 20 Shaft body 25 Resin body formation region 27 Non-resin body region 30 Resin body 31 Main body portion 33a, 33b First and second extending portions

Claims

1. A method for manufacturing a roller shaft, comprising a long shaft body and a plurality of resin bodies fixed to the same-diameter portion of the shaft body in an axially spaced-apart state. Each of the plurality of resin bodies has a main body portion having a length L along the axial direction of the shaft body and a thickness T, and an extension portion that is adjacent to the main body portion in the axial direction of the shaft body and has a smaller diameter than the main body portion by having a thickness thinner than that of the main body portion, and a coating step of applying a molten hot-melt resin to a plurality of resin body forming regions provided on the outer surface of the shaft body while rotating the shaft body around its axis, the axial length La of the molten hot-melt resin being shorter than L and the thickness Ta being thicker than T; a plurality of molding rolls having a small-diameter portion with an axial length of L and a circular cross-sectional shape with a predetermined diameter, a large-diameter portion with a circular cross-sectional shape larger than that of the small-diameter portion, concentric with the small-diameter portion and adjacent to the small-diameter portion in the axial direction, and a support shaft that supports the small-diameter portion and the large-diameter portion on the central axis, the plurality of molding rolls for molding the plurality of resin bodies respectively, and a plurality of housings that rotatably support the plurality of molding rolls around their axes. By using the plurality of molding rolls in a parallel posture with the shaft body and moving them in a direction close to the shaft body rotating around its axis and positioning them at a predetermined molding position, a molding step of molding the hot-melt resin applied to the plurality of resin body forming regions is provided, the housing has a pair of side walls that respectively support one end portion and the other end portion of the support shaft of the corresponding molding roll, and a base end wall that connects the base end portions of the pair of side walls, and has a U-shaped cross-section in a plan view with the free end side, the upper side, and the lower side facing the shaft body being open, the molding position is set to a position where the separation distance between the outer surface of the small-diameter portion and the outer surface of the shaft body is T. By positioning the molding roll at the molding position, a molding space with a thickness of T and an axial length of L and open upper and lower sides is formed between the outer surface of the small-diameter portion and the outer surface of the shaft body. Further, a receiving space with a thickness of Ts thinner than T and open upper and lower sides and communicating with the molding space is formed between the outer surface of the large-diameter portion and the outer surface of the shaft body. In the coating step, the axial length La and the thickness Ta of the hot melt resin to be coated are set such that when the molding roll is positioned at the molding position, the molding space is filled with the hot melt resin and the excess protruding from the molding space flows into the receiving space. A method for manufacturing a roller shaft, characterized by this.

2. The pair of side walls have a vertical length greater than the diameter of the shaft body. Arc-shaped notches opening to the side of the shaft body are provided at the tip surfaces of the pair of side walls. When the molding roll is positioned at the molding position, a part of the shaft body is positioned within the arc-shaped notch in a state where a gap smaller than Ts exists between the outer surface of the arc-shaped notch and the outer surface of the shaft body. The method for manufacturing a roller shaft according to claim 1, characterized by this.

Images