Spiral-wound telescopic shaft

Abstract

To provide a technology of constituting a spirally wound expansion shaft without using a hollow engaging pin.SOLUTION: A first strip-shaped member of a spirally wound expansion shaft has a plurality of first engaging parts arranged in a plurality of rows along a longitudinal direction of the first strip-shaped member, and a second strip-shaped member has a plurality of second engaging parts arranged in a plurality of rows along a longitudinal direction of the second strip-shaped member. The first engaging part is configured as a first hollow protrusion part that protrudes toward an axial line, and the second engaging part is configured to be fitted into the first hollow protrusion part.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a spiral wound telescopic shaft formed by spirally winding two strip members.

Background Art

[0002] Patent Document 1 discloses a spiral reciprocating actuator using a telescopic cylindrical structure. The cylindrical structure is formed by spirally winding a first strip having engaging protrusions and a second strip having engaging holes around an axis with a half-width shift from each other. The engaging protrusions of the first strip are formed by joining solid engaging pins by welding or caulking.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, there are various problems in the configuration using solid engaging pins. For example, when a large number of engaging pins are joined to the first strip to form protrusions, there is a problem that the weight and cost of the first strip increase. In addition, when the telescopic operation of the cylindrical structure is repeated, repeated stress is generated in the two strips, so there is also a problem that fatigue failure occurs starting from the joining part of the engaging pins. Therefore, a configuration that does not use solid engaging pins is desired.

Means for Solving the Problems

[0005] According to one embodiment of the present disclosure, there is provided a helically wound telescopic shaft formed by helically winding a first strip member and a second strip member disposed inside the first strip member around an axis. The first strip member has a plurality of first engaging portions arranged in a plurality of rows along the longitudinal direction of the first strip member, the second strip member has a plurality of second engaging portions arranged in a plurality of rows along the longitudinal direction of the second strip member, the first engaging portion is configured as a first hollow protrusion protruding toward the side of the axis, and the second engaging portion is configured to fit with the first hollow protrusion. The second engaging portion is configured as a second hollow protrusion protruding toward the side of the axis, and the first hollow protrusion and the second hollow protrusion are configured to be in surface contact with each other. The first engaging portion is configured as a first press-formed portion protruding from the first flat belt portion of the first belt member, and the second engaging portion is configured as a second press-formed portion protruding from the second flat belt portion of the second belt member. Each of the first engaging portion and the second engaging portion has a trapezoidal bridge shape with cuts formed on both sides. According to this helically wound telescopic shaft, since the first engaging portion of the first strip member is configured as the first hollow protrusion, a lightweight and low-cost telescopic shaft can be provided as compared with the case of using a solid engaging pin. Further, since the first hollow protrusion of the first belt member and the second hollow protrusion of the second belt member are in surface contact, the contact pressure can be reduced as compared with the case where the engaging portion of the first belt member and the engaging portion of the second belt member are in point contact. As a result, deformation due to contact can be reduced, and noise and vibration can also be reduced. Furthermore, since each of the first engaging portion and the second engaging portion has a trapezoidal bridge shape with cuts formed on both sides, the first engaging portion and the second engaging portion can engage smoothly.

Brief Description of the Drawings

[0006]

Figure 1

Figure 2

Figure 3

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Figure 5

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Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0007] FIG. 1 is an explanatory view showing the configuration of a telescopic device 60 including a spiral-wound telescopic shaft. This telescopic device 60 includes a spiral-wound telescopic shaft 100 formed by spirally winding two belt-like members 110 and 120, a first accommodating portion 10 for accommodating the first belt-like member 110, a second accommodating portion 20 for accommodating the second belt-like member 120, a guide portion 30 for guiding the two belt-like members 110 and 120 and spirally winding them, a driving portion 40 for rotating a guide member 32 of the guide portion 30, and a cap portion 50 attached to the tip of the spiral-wound telescopic shaft 100. When the driving portion 40 is driven and the guide member 32 rotates in one direction, the two belt-like members 110 and 120 are guided by the guide member 32 and spirally wound, and the spiral-wound telescopic shaft 100 extends upward in FIG. 1. When the guide member 32 rotates in the reverse direction, the winding of the two belt-like members 110 and 120 is released, and they are accommodated in the respective accommodating portions 10 and 20, and the spiral-wound telescopic shaft 100 shortens. Instead of rotating the guide member 32, the telescopic shaft 100 itself may be rotated to perform its telescoping. The belt-like members 110 and 120 can be formed of metal. The belt-like members 110 and 120 may be formed of other materials such as deformable resin.

[0008] FIG. 2 is an explanatory view showing how the spiral-wound telescopic shaft 100 is formed by winding two belt-like members 110 and 120. In FIG. 2, for the sake of illustration, the outer shape of the second belt-like member 120 is drawn with a dashed line. The upper left of FIG. 2 shows the state before winding, and the upper right shows how the two belt-like members 110 and 120 overlap in the wound state when flattened in a plane.

[0009] The spiral wound type telescopic shaft 100 is formed by spirally winding a first strip member 110 and a second strip member 120 arranged inside the first strip member 110 around the axis CX. The first strip member 110 has a first flat strip portion 111 and a plurality of first engaging portions 112 arranged in a plurality of rows along the longitudinal direction of the first strip member 110. The first flat strip portion 111 is a flat strip portion without protrusions or recesses. The first engaging portions 112 are arranged in two rows at regular intervals along the longitudinal direction of the first strip member 110. The second strip member 120 has a second flat strip portion 121 and a plurality of second engaging portions 122 arranged in a plurality of rows along the longitudinal direction of the second strip member 120. The second flat strip portion 121 is a flat strip portion without protrusions or recesses. The second engaging portions 122 are arranged in two rows at regular intervals along the longitudinal direction of the second strip member 120.

[0010] In the spiral wound type telescopic shaft 100 shown at the lower part of FIG. 2, the first strip member 110 is wound at a constant pitch Pt along the axis CX. The distance Le between the rows along the direction of the axis CX of the two rows of the first engaging portions 112 is equal to 1 / 2 of the winding pitch Pt. These configurations are the same for the second strip member 120.

[0011] The first strip member 110 has a width W1, and the second strip member 120 has a width W2. These widths W1 and W2 are substantially equal and are set to values slightly smaller than the winding pitch Pt. The two strip members 110 and 120 are overlapped and spirally wound in a state where they are shifted from each other by 1 / 2 of the winding pitch Pt. As a result, the two rows of the first engaging portions 112 of the first strip member 110 engage with the second engaging portions 122 of the two second strip members 120 overlapped inside the first strip member 110.

[0012] FIG. 3 is a cross-sectional view of the spiral wound type telescopic shaft 100 in the first embodiment. The first engaging portion 112 of the first strip member 110 is configured as a first hollow protrusion 114 protruding toward the side of the axis CX. Further, the first engaging portion 112 has an opening 116 at the center.

[0013] The second engaging portion 122 of the second strip member 120 is configured to be fitted with the first engaging portion 112 of the first strip member 110. In the first embodiment, the second engaging portion 122 is also configured as a second hollow protrusion 124 that protrudes toward the axis CX, similar to the first engaging portion 112, and has an opening 126 at its center. The second engaging portion 122 may be configured to have substantially the same shape as the first engaging portion 112, and it is preferable to make the shape of the convex portion slightly larger than that of the first engaging portion 112.

[0014] The inner surface of the first hollow protrusion 114 and the outer surface of the second hollow protrusion 124 are configured to be in surface contact with each other. In this configuration, the contact pressure can be relaxed compared to the case where the two engaging portions are in point contact. As a result, deformation due to contact can be reduced, and noise and vibration can also be reduced.

[0015] The first hollow protrusion 114 preferably extends in a direction inclined from the first flat strip portion 111. Similarly, the second hollow protrusion 124 preferably extends in a direction inclined from the second flat strip portion 121. In this way, while ensuring surface contact between the first hollow protrusion 114 and the second hollow protrusion 124, the two can be smoothly engaged. The angle θ formed between the first hollow protrusion 114 and the first flat strip portion 111 is preferably set in the range of 30 degrees to 85 degrees. The same applies to the second hollow protrusion 124. Generally, the larger the angle θ, the higher the engagement holding force, but if the angle θ is too large, resistance may occur during winding and unwinding. By setting the angle θ in the range of 30 degrees to 85 degrees, it is possible to prevent excessive resistance from occurring during winding and unwinding while maintaining a high engagement holding force.

[0016] The first engaging portion 112 protrudes inward from the inner surface 111i of the first flat strip portion 111. On the other hand, there is no portion that protrudes outward from the outer surface 111o of the first flat strip portion 111. These configurations are the same for the second strip member 120 as well. In the present disclosure, "inner side" means the inner side of the spiral wound type telescopic shaft 100, that is, the side of the axis CX, and "outer side" means the outer side of the spiral wound type telescopic shaft 100.

[0017] FIG. 4 is a cross-sectional view of the spiral-wound type telescopic shaft in the comparative example. In this comparative example, the first strip member 11 has a first flat strip portion 12 and a solid engagement pin 14. The engagement pin 14 is joined to the first flat strip portion 12 by welding, and a weld mark 16 protruding outside the first flat strip portion 12 is formed. The second strip member 21 has a second flat strip portion 22 and an engagement hole 24.

[0018] In the spiral-wound type telescopic shaft of this comparative example, since it is necessary to join a large number of engagement pins 14 to the first flat strip portion 12, the weight and cost of the first strip member 11 increase. Further, when the spiral-wound type telescopic shaft is repeatedly expanded and contracted, fatigue failure may occur starting from the joining portion of the engagement pin 14. Further, since it has a portion protruding outward from the outer surface of the first strip member 11, the interference and resistance when guided by the guide portion 30 increase.

[0019] On the other hand, in the spiral-wound type telescopic shaft 100 of the first embodiment shown in FIG. 3, since the first engaging portion 112 of the first strip member 110 is configured as a hollow protrusion, a spiral-wound type telescopic shaft that is lighter and less costly than the case of using a solid engagement pin can be provided. Further, since the first hollow protrusion 114 of the first strip member 110 and the second hollow protrusion 124 of the second strip member 120 are in surface contact, the contact pressure can be relaxed as compared with the case where the two engaging portions are in point contact. As a result, deformation due to contact can be reduced, and noise and vibration can be reduced. Further, since the first strip member 110 does not have a portion protruding outward from the outer surface 111o of the first flat strip portion 111, the interference and resistance when guided by the guide portion 30 are reduced, and the spiral-wound type telescopic shaft 100 can be smoothly extended and contracted.

[0020] FIG. 5 is an explanatory view showing a press forming method of the first strip member 110 of the first embodiment. The upper part of FIG. 5 shows the state before press forming, and the center shows the state after press forming. The lower part of FIG. 5 shows a perspective view of the first engaging portion 112 of the first strip member 110.

[0021] In the state before press forming, a plurality of holes 118 are formed in the first flat belt portion 111. A die 70 and a punch 71 are used for press forming. The die 70 is disposed around the hole 118. During press forming, as the punch 71 advances toward the hole 118, a first engaging portion 112 having a first hollow protrusion 114 and an opening 116 is formed. Thus, the first hollow protrusion 114 can be configured as a press-formed portion protruding inward from the first flat belt portion 111. The second engaging portion 122 of the second belt member 120 can also be formed in the same manner by press forming. By using press forming, the first hollow protrusion 114 and the second hollow protrusion 124 can be easily formed.

[0022] As can be understood from FIG. 5, the first engaging portion 112 of the first embodiment has a frustoconical shape with holes. By forming the first engaging portion 112 by press forming, the angle of the first hollow protrusion 114 can be set large. As described with reference to FIG. 3, the angle θ formed between the first hollow protrusion 114 and the first flat belt portion 111 is preferably set in the range of 30 degrees to 85 degrees. Note that the boundary portion between the first hollow protrusion 114 and the first flat belt portion 111 is preferably not an acute angle shape but a gentle gradual change shape such as an R shape. In this way, stress concentration can be prevented from occurring at the boundary portion between the first hollow protrusion 114 and the first flat belt portion 111.

[0023] As described above, in the first embodiment described above, since the first engaging portion 112 of the first belt member 110 is configured as the first hollow protrusion 114, a lightweight and low-cost telescopic shaft can be provided as compared with the case of using a solid engagement pin. Further, since the first hollow protrusion 114 and the second hollow protrusion 124 are configured to be in surface contact, the contact pressure can be relaxed as compared with the case where the two engaging portions are in point contact. As a result, deformation due to contact can be reduced, and noise and vibration can be reduced.

[0024] FIG. 6 is an explanatory view showing a press forming method of the first belt-like member 210 of the second embodiment. As shown in the lower part of FIG. 6, the first belt-like member 210 of the second embodiment has a first flat belt portion 211 and a first engaging portion 212, and the first engaging portion 212 has a first hollow protrusion 214 and a top portion 216. There is no opening in the top portion 216. In the example of FIG. 6, the top portion 216 is substantially flat. That is, the first engaging portion 212 is formed so as to have a truncated cone shape with the top portion 216 closed. The top portion 216 may be flat or may have a dome shape.

[0025] In the state before press forming, no hole is formed in the first flat belt portion 211. For press forming, a die 70 and a punch 72 are used. The die 70 is disposed around the formation position of the first engaging portion 212. The punch 72 has a truncated cone shape conforming to the shape of the first engaging portion 212. During press forming, when the punch 72 advances to the formation position of the first engaging portion 212, the first engaging portion 212 having the first hollow protrusion 214 and the top portion 216 is formed. That is, the first engaging portion 212 is press formed. Thus, the first hollow protrusion 214 of the second embodiment can also be configured as a press formed portion protruding from the first flat belt portion 211. Similarly, the second engaging portion of the second belt-like member can be formed into a truncated cone shape with the top closed by press forming.

[0026] In the second embodiment, since it is not necessary to form an opening in the first belt-like member 210, the manufacturing process can be simplified as compared with the first embodiment. However, the first embodiment has an advantage that the first belt-like member 110 can be made lighter because the first belt-like member 110 has the opening 116. Also, in the first embodiment, there is an advantage that it is easy to set the angle θ of the first hollow protrusion 114 to a larger value. These advantages are the same for the second belt-like member.

[0027] FIG. 7 is an explanatory view showing a press forming method of the first strip member 310 of the third embodiment. As shown in the lower part of FIG. 7, the first strip member 310 of the third embodiment has a first flat strip portion 311 and a first engaging portion 312. The first engaging portion 312 has a first hollow protrusion 314 and a top portion 316, and has a trapezoidal bridge shape. The first hollow protrusion 314 is formed as the left and right legs of the trapezoid, and the top portion 316 is configured as the upper bottom of the trapezoid. Cuts 318 are formed on both sides of the trapezoidal bridge-shaped first engaging portion 312. The cut 318 is a portion where the first flat strip portion 311 and the first engaging portion 312 are separated. The cuts 318 on both sides of the first engaging portion 312 communicate with the inside of the first engaging portion 312.

[0028] There is no opening at the top portion 316 of the first engaging portion 312, and it is substantially flat. Also, the first hollow protrusions 314 on both sides of the top portion 316 are also substantially flat. The direction D1 in which the two first hollow protrusions 314 and the top portion 316 are arranged is preferably an oblique direction having an appropriate angle of less than 90 degrees with respect to the longitudinal direction of the first strip member 310. The reason for this is that if the direction D1 is arranged parallel to the longitudinal direction of the first strip member 310, it is easy to wind but may be slightly loose, while if it is arranged vertically, the holding force is high but it may be difficult to wind. That is, if the direction D1 is inclined with respect to the longitudinal direction of the first strip member 310, it can be made easy to wind and difficult to loosen.

[0029] In the state before press forming, no hole is formed in the first flat band portion 311, but as shown in the center of FIG. 7, cuts 318 are formed on both sides of the formation position of the first engaging portion 312. For press forming, a die 70 and a punch 73 are used. The die 70 is disposed around the formation position of the first engaging portion 312. The punch 73 has a quadrangular prism shape conforming to the shape of the first engaging portion 312. During press forming, as the punch 73 advances to the formation position of the first engaging portion 312, the first engaging portion 312 having the first hollow protrusion 314 and the top 316 is formed. Thus, the first hollow protrusion 314 of the third embodiment can also be configured as a press formed portion protruding from the first flat band portion 311. Similarly, the second engaging portion of the second belt-like member can be formed into a trapezoidal bridge shape by press forming.

[0030] In the third embodiment, since there is no need to form an opening, the manufacturing process can be simplified compared to the first embodiment. Further, in the third embodiment, engagement can be smoothly performed while bearing the force on both side portions of the first engaging portion 312 in which the cuts 318 are formed. In particular, if the first engaging portion of the first belt-like member and the second engaging portion of the second belt-like member are each formed in a trapezoidal bridge shape, the first engaging portion and the second engaging portion can be smoothly engaged with each other.

[0031] FIG. 8 is a cross-sectional view of a spiral wound type telescopic shaft 400 according to a fourth embodiment. The spiral wound type telescopic shaft 400 is formed by spirally winding a first belt-like member 410 and a second belt-like member 420. The first belt-like member 410 has the same shape as the first belt-like member 110 of the first embodiment shown in FIG. 3. That is, the first belt-like member 410 has a first flat band portion 411 and a plurality of first engaging portions 412, and the first engaging portion 412 includes a first hollow protrusion 414 and an opening 416.

[0032] The second strip member 420 of the fourth embodiment has a second flat strip portion 421 and a plurality of second engaging portions 422. The second engaging portion 422 is formed as an engaging hole. Also in this fourth embodiment, in that the second engaging portion 422 is configured to fit with the first hollow protrusion 414 of the first engaging portion 412, it is the same as the first to third embodiments described above.

[0033] In the spiral wound type telescopic shaft 400 of the fourth embodiment as well, since the first engaging portion 412 of the first strip member 410 is configured as the first hollow protrusion 414, a telescopic shaft that is lighter and less costly than the case of using a solid engaging pin can be provided. However, in the fourth embodiment, the peripheral edge portion of the second engaging portion 422 of the second strip member 420 engages with the first engaging portion 412 of the first strip member 410 in point contact. On the other hand, in the first to third embodiments described above, since the first engaging portion and the second engaging portion are in surface contact, there is an advantage that vibrations and noises caused by point contact are less likely to occur.

[0034] FIG. 9 is a cross-sectional view of a spiral wound type telescopic shaft 500 in the fifth embodiment. The spiral wound type telescopic shaft 500 is formed by spirally winding a first strip member 510 and a second strip member 520. The first strip member 510 has the same shape as the first strip member 110 of the first embodiment shown in FIG. 3. That is, the first strip member 510 has a first flat strip portion 511 and a plurality of first engaging portions 512, and the first engaging portion 512 includes a first hollow protrusion 514 and an opening 516.

[0035] The second strip member 520 of the fifth embodiment has a second flat strip portion 521 and a plurality of second engaging portions 522. The second engaging portion 522 is formed as an engaging hole. The difference from the fourth embodiment shown in FIG. 8 is only that the peripheral edge portion 524 of the hole of the second engaging portion 522 that contacts the first engaging portion 512 is chamfered. R processing may be performed instead of chamfering. By doing so, the contact area between the first engaging portion 512 and the second engaging portion 522 can be increased compared to the fourth embodiment, so that vibrations and noises caused by point contact can be made less likely to occur.

[0036] The present disclosure is not limited to the above-described embodiments, embodiments, and modifications, and can be implemented in various configurations without departing from the gist thereof. For example, embodiments, embodiments, and modifications corresponding to the technical features in each form described in the summary section of the disclosure can be appropriately replaced or combined in order to solve some or all of the above-described problems or to achieve some or all of the above-described effects. Further, if the technical feature is not described as essential in this specification, it can be appropriately deleted.

[0037] (1) According to one embodiment of the present disclosure, there is provided a helically wound telescopic shaft formed by helically winding a first strip member and a second strip member disposed inside the first strip member around an axis. The first strip member has a plurality of first engaging portions arranged in a plurality of rows along the longitudinal direction of the first strip member, and the second strip member has a plurality of second engaging portions arranged in a plurality of rows along the longitudinal direction of the second strip member. The first engaging portion is configured as a first hollow protrusion protruding toward the axis side, and the second engaging portion is configured to fit with the first hollow protrusion. According to this helically wound telescopic shaft, since the first engaging portion of the first strip member is configured as the first hollow protrusion, a lightweight and low-cost telescopic shaft can be provided as compared with the case of using a solid engaging pin.

[0038] (2) In the above helically wound telescopic shaft, the second engaging portion is configured as a second hollow protrusion protruding toward the axis side, The first hollow protrusion and the second hollow protrusion may be configured to be in surface contact with each other. According to this helically wound telescopic shaft, since the first hollow protrusion of the first strip member and the second hollow protrusion of the second strip member are in surface contact, the contact pressure can be relaxed as compared with the case where the engaging portion of the first strip member and the engaging portion of the second strip member are in point contact. As a result, deformation due to contact can be reduced, and noise and vibration can be reduced.

[0039] (3) In the above-described helically wound telescopic shaft, the first engaging portion is configured as a first press-formed portion protruding from a first flat belt portion of the first belt-like member. The second engaging portion may be configured as a second press-formed portion protruding from a second flat belt portion of the second belt-like member. According to this helically wound telescopic shaft, the first engaging portion and the second engaging portion can be easily formed.

[0040] (4) In the above-described helically wound telescopic shaft, each of the first engaging portion and the second engaging portion may have an opening at the center. According to this helically wound telescopic shaft, the weight can be further reduced.

[0041] (5) In the above-described helically wound telescopic shaft, each of the first engaging portion and the second engaging portion may have a frustum shape with a closed top. According to this helically wound telescopic shaft, the first engaging portion and the second engaging portion can engage smoothly.

[0042] (6) In the above-described helically wound telescopic shaft, each of the first engaging portion and the second engaging portion may have a trapezoidal bridge shape with cuts formed on both sides. According to this helically wound telescopic shaft, the first engaging portion and the second engaging portion can engage smoothly.

Explanation of Reference Numerals

[0043] 10…First housing portion, 11…First strip member, 12…First flat strip portion, 14…Engagement pin, 16…Weld mark, 20…Second housing portion, 21…Second strip member, 22…Second flat strip portion, 24…Engagement hole, 30…Guide portion, 32…Guide member, 40…Drive portion, 50…Cap portion, 60…Expansion and contraction device, 70…Die, 71…Punch, 72…Punch, 73…Punch, 100…Spiral-wound type telescopic shaft, 110…First strip member, 111…First flat strip portion, 111i…Inner surface, 111o…Outer surface, 112…First engagement portion, 114…First hollow protrusion, 116…Opening, 118…Hole, 120…Second strip member, 121…Second flat strip portion, 122…Second engagement portion, 124…Second hollow protrusion, 126…Opening, 210…First strip member, 211…First flat strip portion, 212…First engagement portion, 214…First hollow protrusion, 216…Top, 310…First strip member, 311…First flat strip portion, 312…First engagement portion, 314…First hollow protrusion, 316…Top, 318…Cut, 400…Spiral-wound type telescopic shaft, 410…First strip member, 411…First flat strip portion, 412…First engagement portion, 414…First hollow protrusion, 416…Opening, 420…Second strip member, 421…Second flat strip portion, 422…Second engagement portion, 500…Spiral-wound type telescopic shaft, 510…First strip member, 511…First flat strip portion, 512…First engagement portion, 514…First hollow protrusion, 516…Opening, 520…Second strip member, 521…Second flat strip portion, 522…Second engagement portion, 524…Peripheral portion

Claims

【Claim 1】 A spiral wound type telescopic shaft formed by spirally winding a first strip-shaped member and a second strip-shaped member disposed inside the first strip-shaped member around an axis, wherein the first strip-shaped member has a plurality of first engaging portions arranged in a plurality of rows along the longitudinal direction of the first strip-shaped member, the second strip-shaped member has a plurality of second engaging portions arranged in a plurality of rows along the longitudinal direction of the second strip-shaped member, the first engaging portion is configured as a first hollow protrusion protruding toward the axis side, the second engaging portion is configured to fit with the first hollow protrusion, the second engaging portion is configured as a second hollow protrusion protruding toward the axis side, the first hollow protrusion and the second hollow protrusion are configured to be in surface contact with each other, the first engaging portion is configured as a first press-molded portion protruding from a first flat strip portion of the first strip-shaped member, the second engaging portion is configured as a second press-molded portion protruding from a second flat strip portion of the second strip-shaped member, each of the first engaging portion and the second engaging portion has a trapezoidal bridge shape with cuts formed on both sides, the spiral wound type telescopic shaft.

Images