Helical reciprocating mechanism

Abstract

To provide a spiral advance / retract operation device which can suppress a deflection of a cylindrical telescopic body.SOLUTION: A spiral advance / retract operation device constitutes a cylindrical telescopic body 100 by winding a first band material 110 and a second band material 120 around a common axial line CX while spirally superimposing the band materials in a state that the band materials are displaced from each other in the axial line direction. The first band material comprises a first engagement protrusion row L1 and a second engagement protrusion row L2, and is spirally wound while forming a spiral first clearance C1. The second band material comprises a first engagement part row L3 and a second engagement part row L4, and is spirally wound while forming a spiral second clearance C2. One of the first clearance and the second clearance is set so that one of the first band materials opposing each other across the first clearance and the second band materials opposing each other across the second clearance are in contact with each other before the engagement between the engagement part and the engagement protrusion is released when the cylindrical telescopic body is deflected.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] This disclosure relates to a spiral reciprocating actuator. [Background technology]

[0002] Patent Document 1 discloses a spiral retractable mechanism that constructs a cylindrical expandable body by spirally overlapping and winding a first strip material and a second strip material placed inside the first strip material, with the strip material offset from each other in the axial direction around a common axis (offset by half a width).

[0003] The first strip material comprises a first row of engaging protrusions and a second row of engaging protrusions, which are arranged in its longitudinal direction and consist of a plurality of engaging protrusions that are convex toward the axis. On the other hand, the second strip material comprises a first row of engaging parts and a second row of engaging parts, which are arranged in its longitudinal direction and consist of a plurality of engaging parts. The engaging parts are configured so that the engaging protrusions can engage with the first strip material and the second strip material in a spiral overlapping and winding manner. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 4607772 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, since the strip material (first strip material and second strip material) is wound in a spiral shape while forming a spiral gap, there is a problem that when an external force is applied to the cylindrical expandable body formed by winding this strip material in a spiral shape, the deflection of the cylindrical expandable body becomes large. This disclosure was made to solve this problem and provides a spiral reciprocating mechanism that can suppress the deflection of the cylindrical expandable body when an external force is applied to it. [Means for solving the problem]

[0006] The helical retractable mechanism according to this disclosure is a helical retractable mechanism that constitutes a cylindrical expandable body by spirally overlapping and winding a first strip material and a second strip material disposed inside the first strip material around a common axis while being offset from each other in the axial direction, wherein the first strip material is provided with a first row of engagement protrusions and a second row of engagement protrusions arranged in its longitudinal direction and composed of a plurality of engagement protrusions convex toward the axis, and is wound spirally while forming a helical first gap, and the second strip material is provided with a first row of engagement parts and a second row of engagement parts composed of a plurality of engagement parts arranged in its longitudinal direction, and is helical first The first and second strips are wound spirally while forming two gaps, and the engaging portion is configured such that the engaging projection engages with the first and second strips in a spirally overlapping and wound state, and when an external force is applied to the cylindrical expandable body and the tip of the cylindrical expandable body is displaced relative to the base end, causing the cylindrical expandable body to bend, at least one of the first strips facing each other across the first gap and the second strips facing each other across the second gap are set so that before the engagement between the engaging portion and the engaging projection disengages, at least one of the first strips facing each other across the first gap and the second strips facing each other across the second gap come into contact with each other.

[0007] This configuration makes it possible to suppress the deflection of the cylindrical expandable body when an external force is applied to it. This is because, when an external force is applied to the cylindrical expandable body, the force is borne not only by the engagement between the engaging projection and the engaging part, but also by the contact between the opposing strip materials (the sides in the width direction of the first strip material and the sides in the width direction of the second strip material) separated by the spiral gap (first gap, second gap).

[0008] In the above-described spiral reciprocating actuator, when an external force is applied to the cylindrical telescopic body and the tip of the cylindrical telescopic body is displaced relative to the base end portion, causing the cylindrical telescopic body to bend, the amount of bending is denoted as B, the first gap is denoted as C1, the second gap is denoted as C2, and the diameter of the cylindrical telescopic body is denoted as D. At least one of C1 and C2 may be set such that B ≤ D. Thereby, when the cylindrical telescopic body is used as a device for transporting a load, bending can occur in the entire cylindrical telescopic body, and it is possible to suppress the spiral reciprocating actuator from tipping over.

Advantages of the Invention

[0009] According to the present disclosure, it is possible to provide a spiral reciprocating actuator that can suppress the bending of a cylindrical telescopic body when an external force is applied to the cylindrical telescopic body.

Brief Description of the Drawings

[0010] [[ID=…]] [Figure 1] An explanatory diagram showing the configuration of a telescopic device including a spiral wound telescopic shaft. [Figure 2] An explanatory diagram showing a state of forming a spiral wound telescopic shaft. [Figure 3] (a) Cross-sectional view of a spiral wound telescopic shaft in a reference example, (b) Cross-sectional view of a spiral wound telescopic shaft in a comparative example, (c) Diagram showing a modified example of the second engaging portion 122, (d) Diagram showing a modified example of the second engaging portion 122. [Figure 4] A diagram showing a spiral wound telescopic shaft bent by an applied external force. [Figure 5] (a) Partial cross-sectional view of a spiral wound telescopic shaft 100A, (b) Partial cross-sectional view of a spiral wound telescopic shaft 100. [Figure 6] A diagram showing the force acting on the engaging pin 14 when an external force is applied to the spiral wound telescopic shaft 100A. [Figure 7] A diagram for explaining the conditions for preventing the telescopic device 60 from tipping over.

Embodiments for Carrying Out the Invention

[0011] <Reference Example> Referring to FIGS. 1 to 3, the telescopic device 60 (spiral telescopic actuator) of the reference example will be described.

[0012] FIG. 1 is an explanatory diagram showing the configuration of a telescopic device 60 including a spiral wound telescopic shaft. The telescopic device 60 of this reference example includes a spiral wound telescopic shaft 100 formed by spirally winding two strip members 110 and 120, a first housing portion 10 for housing the first strip member 110, a second housing portion 20 for housing the second strip member 120, a guide portion 30 for guiding and spirally winding the two strip members 110 and 120, a drive 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 guide member 32 is driven by the drive portion 40 to rotate in one direction, the two strip 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 strip members 110 and 120 is released, and they are housed in the respective housing portions 10 and 20, and the spiral wound telescopic shaft 100 contracts. Instead of rotating the guide member 32, the spiral wound telescopic shaft 100 itself may be rotated to perform its telescoping. The strip members 110 and 120 can be formed of metal (for example, a metal having spring properties such as stainless steel for springs). The strip members 110 and 120 may be formed of other materials such as deformable resin.

[0013] FIG. 2 is an explanatory diagram showing how the spiral wound telescopic shaft 100 is formed by winding two strip members 110 and 120. In FIG. 2, for the sake of illustration, the outer shape of the second strip 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 strip members 110 and 120 overlap in the wound state, unfolded in a plane.

[0014] The spiral-wound telescopic shaft 100 is formed by spirally winding a first strip-shaped member 110 and a second strip-shaped member 120, which is positioned inside the first strip-shaped member 110, around an axis CX. The first strip-shaped member 110 has a first flat strip portion 111 and a plurality of first engaging portions 112 arranged in multiple rows along the longitudinal direction of the first strip-shaped member 110. The first flat strip portion 111 is a flat, strip-shaped 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-shaped member 110. The second strip-shaped member 120 has a second flat strip portion 121 and a plurality of second engaging portions 122 arranged in multiple rows along the longitudinal direction of the second strip-shaped member 120. The second flat strip portion 121 is a flat, strip-shaped portion without protrusions or recesses. The second engaging portion 122 is arranged in two rows at regular intervals along the longitudinal direction of the second strip-shaped member 120.

[0015] In the spiral-wound telescopic shaft 100 shown in the lower part of Figure 2, the first strip-shaped member 110 is wound at a constant pitch Pt along the axis CX. The distance Le between the two rows of first engaging portions 112 along the direction of axis CX is equal to half the winding pitch Pt. The second strip-shaped member 120 has a similar configuration.

[0016] The first strip-shaped member 110 has a width W1, and the second strip-shaped member 120 has a width W2. These widths W1 and W2 are approximately equal and set to a value slightly smaller than the winding pitch Pt. The two strip-shaped members 110 and 120 are overlapped and wound spirally, offset from each other by half the winding pitch Pt. As a result, the two rows of first engaging portions 112 of the first strip-shaped member 110 engage with the second engaging portions 122 of the two second strip-shaped members 120 that are overlapped inside the first strip-shaped member 110.

[0017] Figure 3(a) is a cross-sectional view of the spiral winding type telescopic shaft 100 in a reference example. The first engaging portion 112 of the first strip-shaped member 110 is configured as a first hollow projection 114 (hollow frustoconical projection) that protrudes toward the axis CX. The first engaging portion 112 also has an opening 116 in the center. The opening 116 may be omitted. That is, the tip of the first hollow projection 114 may be closed.

[0018] The second engaging portion 122 of the second strip-shaped member 120 is configured to engage with the first engaging portion 112 of the first strip-shaped member 110. In the reference example, the second engaging portion 122 is also configured as a second hollow projection 124 (hollow frustoconical projection) protruding toward the axis CX, similar to the first engaging portion 112, and has an opening 126 in its center. The opening 126 may be omitted. That is, the tip of the second hollow projection 124 may be closed. The second engaging portion 122 may be configured to have substantially the same shape as the first engaging portion 112, and it is preferable that the shape of the protrusion be slightly larger than that of the first engaging portion 112.

[0019] The inner surface of the first hollow projection 114 and the outer surface of the second hollow projection 124 are configured to be in surface contact with each other. In this configuration, the contact pressure can be reduced compared to when the two engaging parts are in point contact. As a result, deformation due to contact can be reduced, and noise and vibration can also be reduced.

[0020] The angle θ between the first hollow projection 114 and the first flat band 111 is preferably set in the range of 30 to 85 degrees. The same applies to the second hollow projection 124.

[0021] The first engaging portion 112 protrudes inward (towards the axis CX) 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-shaped member 120.

[0022] Figure 3(b) is a cross-sectional view of a spiral-wound telescopic shaft in a comparative example. In this comparative example, the first strip-shaped member 11 has a first flat strip portion 12 and a solid engaging pin 14. The engaging pin 14 is joined to the first flat strip portion 12 by welding, and a weld mark 16 is formed that protrudes to the outside of the first flat strip portion 12. The second strip-shaped member 21 has a second flat strip portion 22 and an engaging hole 24.

[0023] In this comparative example, the spiral-wound telescopic shaft requires numerous engagement pins 14 to be joined to the first flat strip portion 12, which increases the weight and cost of the first strip-shaped member 11.

[0024] On the other hand, in the spiral winding type telescopic shaft 100 of the reference example shown in Figure 3(a), the first engaging portion 112 of the first strip-shaped member 110 is configured as a hollow projection, so a lighter and lower-cost spiral winding type telescopic shaft can be provided compared to using a solid engaging pin.

[0025] The first hollow projection 114 can be formed, for example, by press molding the first strip-shaped member 110 before the first hollow projection 114 is formed. The same applies to the second hollow projection 124.

[0026] As described above, in the above-mentioned reference example, the first engaging portion 112 of the first strip-shaped member 110 is configured as the first hollow projection 114, so a lightweight and low-cost telescopic shaft can be provided compared to using a solid engaging pin. Furthermore, since the first hollow projection 114 and the second hollow projection 124 are configured to make surface contact, the contact pressure can be reduced compared to when the two engaging portions make point contact. As a result, deformation due to contact can be reduced, and noise and vibration can also be reduced.

[0027] Figures 3(c) and 3(d) show modified examples of the second engaging portion 122. As shown in Figure 3(c), instead of the second hollow projection 124, an engaging hole (through hole) formed in the second strip-shaped member 120 may be used as the second engaging portion 122. In this case, as shown in Figure 3(d), the peripheral portion 124 of the second engaging portion 122 (engaging hole) may be chamfered, or instead of chamfering, it may be given a rounded edge.

[0028] <Embodiment> First, we will explain the problems that the inventors have identified with the telescopic device 60 (helical reciprocating device) of the above reference example.

[0029] As described above, in the above reference example, the telescopic device 60 (helical reciprocating operating device) is configured as a helical-wound telescopic shaft 100 (an example of a cylindrical telescopic body in this disclosure) by spirally overlapping and winding a first strip-shaped member 110 (an example of a first strip material in this disclosure) and a second strip-shaped member 120 (an example of a second strip material in this disclosure) which is arranged inside the first strip-shaped member 110, with the strips offset from each other in the direction of the axis CX around a common axis CX (offset by half a width).

[0030] For example, the first strip-shaped member 110 in the above reference example includes a first row of engaging protrusions L1 and a second row of engaging protrusions L2 (see Figure 2), which are composed of a plurality of first hollow protrusions 114 (see Figure 3(a); an example of an engaging protrusion in this disclosure; hereinafter also referred to as engaging protrusion 114) arranged in its longitudinal direction and convex toward the axis CX. This first strip-shaped member 110 is wound in a spiral shape while forming a spiral first gap C1 (see Figures 1 and 2).

[0031] On the other hand, the second strip-shaped member 120 of the above reference example is provided with a first row of engaging parts L3 and a second row of engaging parts L4 (see Figure 2), which are composed of a plurality of second engaging parts 122 (an example of an engaging part of this disclosure) arranged in the longitudinal direction thereof. This second strip-shaped member 120 is wound in a spiral shape while forming a spiral second gap C2 (see Figure 2).

[0032] The second engaging portion 122 is configured such that the engaging projection 114 can engage with the first strip-shaped member 110 and the second strip-shaped member 120 in a spiral manner when they are wrapped around each other.

[0033] As described above, when using a spiral-wound telescopic shaft 100 constructed by spirally overlapping and winding a first strip-shaped member 110 and a second strip-shaped member 120 positioned inside the first strip-shaped member 110 around a common axis CX, while being offset from each other in the direction of the axis CX, the following problems arise.

[0034] The following will explain this issue using comparative examples.

[0035] The comparative example is the spiral-wound telescopic shaft (cylindrical telescopic body) described in Patent Document 1 above. Hereinafter, it will be referred to as the spiral-wound telescopic shaft 100A. The spiral-wound telescopic shaft 100A of the comparative example has the same configuration as the spiral-wound telescopic shaft 100 of this embodiment, except that the spiral gap (first gap C1 or second gap C2) is set to be larger than that of the spiral-wound telescopic shaft 100 of this embodiment. Hereinafter, the spiral-wound telescopic shaft 100A of the comparative example will be described focusing on the differences from the spiral-wound telescopic shaft 100 of this embodiment, and the same components will be denoted by the same reference numerals and their descriptions will be omitted as appropriate.

[0036] Figure 4 shows a spiral-wound telescopic shaft that has been deflected by an external force. In Figure 4, the rectangle B1 drawn with a dotted line represents the spiral-wound telescopic shaft (spiral-wound telescopic shaft 100 or 100A) before deflection. The arrow indicated by the symbol AR1 represents the external force applied to the spiral-wound telescopic shaft. The symbol L represents the total length of the spiral-wound telescopic shaft. The symbol D represents the diameter of the spiral-wound telescopic shaft. The symbol W represents the width of the strip-shaped member. The symbol B represents the amount of deflection of the spiral-wound telescopic shaft. The symbol C represents the spiral gap of the strip-shaped member.

[0037] As shown in Figure 4, we consider a case where an external force (for example, see arrow AR1) is applied to the spiral-wound telescopic shaft 100A, causing the tip of the spiral-wound telescopic shaft 100A to be displaced relative to its base, resulting in the spiral-wound telescopic shaft 100A bending.

[0038] Here, the relationship between the winding pitch Pt of the strip member (see Figure 2) and the width W of the strip member is expressed by the following equation 1, where θ R (See Figure 2) This is the winding lead angle.

[0039] Pt = W ÷ cosθ R +C...(Formula 1) For example, the winding pitch Pt = 44 mm, the width W = 38 mm, and the winding lead angle θ of the strip-shaped member. R If the angle is 8°, the spiral gap C will be 5.63 mm.

[0040] In the comparative example, the spiral gap C is set to be greater than 0 (not 0) when the spiral-wound telescopic shaft 100A is deflected (see Figure 5(a)). Figure 5(a) is a partial cross-sectional view of the spiral-wound telescopic shaft 100A. In Figure 5(a), the left side is a partial cross-sectional view of the spiral-wound telescopic shaft 100A (before the spiral-wound telescopic shaft 100A is deflected), and the center is a partial cross-sectional view of the spiral-wound telescopic shaft 100A (after the spiral-wound telescopic shaft 100A is deflected).

[0041] Figure 6 illustrates the forces acting on the engagement pin 14 when an external force is applied to the spiral-wound telescopic shaft 100A. In Figure 6, the symbol F represents the force acting on the engagement pin 14 when an external force (see, for example, arrow AR1) is applied to the spiral-wound telescopic shaft 100A. Angle θ 14 This represents the pin angle of the engaging pin 14. F × cosθ 14 This represents the force that attempts to disengage the engagement between the engagement pin 14 and the engagement hole 24. F × cosθ 14 is, θ 14 The smaller the value, the larger the value becomes. μ × F × sinθ 14 This represents the resistance force (frictional force) determined by the angle of the inclination of the engaging pin 14 and the coefficient of friction μ.

[0042] In FIG. 6, F×cosθ 14 >μ×F×sinθ 14 When the relationship is such that slippage occurs between the engaging pin 14 and the engaging hole 24 (actually, it is not just a simple balance of forces in the vertical direction as shown in FIG. 6, but a complex state of force equilibrium with forces in the circumferential direction also added).

[0043] The above-mentioned slippage occurs not only between one engaging pin 14 and one engaging hole 24, but also between a plurality of engaging pins 14 and a plurality of engaging holes 24, and the amounts of slippage of each are added together. As a result, the entire spiral-wound telescopic shaft 100A deflects by the amount B of deflection (see FIG. 4).

[0044] At that time, in the comparative example, since the spiral gap C is set to be greater than 0 (not to be 0) when the spiral-wound telescopic shaft 100A deflects (see FIG. 5(a)), when an external force (for example, see arrow AR1) is applied to the spiral-wound telescopic shaft 100A, this force will be borne only by the engagement between the engaging pin 14 and the engaging hole 24 (see the graph at the right end in FIG. 5(a)).

[0045] Therefore, there is a problem that the above-mentioned slippage is likely to occur (the engagement between the engaging pin 14 and the engaging hole 24 is likely to disengage), and the spiral-wound telescopic shaft 100A is likely to deflect (the first problem).

[0046] Also, in the comparative example, when the amount of slippage of the engaging pin 14 exceeds a certain value (for example, when the amount of slippage of the engaging pin 14 exceeds the height of the engaging pin 14), the engagement between the engaging pin 14 and the engaging hole 24 is completely disengaged (see the graph at the right end in FIG. 5(a)), and there is also a problem that the first belt-like member 110 and the second belt-like member 120 are separated from each other, and the shape of the spiral-wound telescopic shaft 100A cannot be maintained (the second problem).

[0047] Furthermore, in the comparative example, when the spiral-wound telescopic shaft 100A is used in equipment for transporting goods, for example, when a load is placed on top of the spiral-wound telescopic shaft 100A, there is a problem that the entire spiral-wound telescopic shaft 100A will deflect, and the telescopic device 60 may tip over (third problem). For example, when a heavy object is placed on top of the spiral-wound telescopic shaft 100A at a position shifted horizontally from the central axis (axis CX), an eccentric load acts on the spiral-wound telescopic shaft 100A, causing the entire spiral-wound telescopic shaft 100A to deflect, and there is a problem that the telescopic device 60 may tip over.

[0048] Next, as an embodiment, an example configuration for solving the first to third problems described above will be explained.

[0049] This configuration example can also be applied to the first strip-shaped member 11 and the second strip-shaped member 21 of the comparative example above, the first strip-shaped member 110 and the second strip-shaped member 120 of the reference example above, and other strip-shaped members. Below, we will describe an example in which this configuration example is applied to the first strip-shaped member 11 of the comparative example above.

[0050] Figure 5(b) is a partial cross-sectional view of the spiral-wound telescopic shaft 100. In Figure 5(b), the left side is a partial cross-sectional view of the spiral-wound telescopic shaft 100 (before the spiral-wound telescopic shaft 100 bends), and the center is a partial cross-sectional view of the spiral-wound telescopic shaft 100 (after the spiral-wound telescopic shaft 100 bends).

[0051] As shown on the left side of Figure 5(b), the spiral gap C (for example, the first gap C1) of the spiral winding type telescopic shaft 100 of this embodiment is set to be narrower than the spiral gap C (see Figure 5(a)) of the comparative example spiral winding type telescopic shaft 100A. Specifically, when an external force (for example, see arrow AR1) is applied to the spiral winding type telescopic shaft 100 and the tip of the spiral winding type telescopic shaft 100 is displaced relative to the base end, causing the spiral winding type telescopic shaft 100 to bend, the spiral gap C is set so that the opposing strip-shaped members (for example, the widthwise sides of the first strip-shaped member 110) across the spiral gap C come into contact with each other (see center of Figure 5(b)) before the engagement between the engagement pin 14 and the engagement hole 24 is disengaged. In addition, the spiral gap C may be set taking into account the manufacturing tolerances of the strip-shaped members, etc. Note that "before the engagement between the engagement pin 14 and the engagement hole 24 is released" means before slippage occurs between the engagement pin 14 and the engagement hole 24, or before the amount of slippage of the engagement pin 14 exceeds a certain value (for example, before the amount of slippage of the engagement pin 14 exceeds the height of the engagement pin 14).

[0052] By setting the spiral gap C in this way, when an external force (for example, see arrow AR1) is applied to the spiral winding telescopic shaft 100, the opposing strip-shaped members (for example, the widthwise sides of the first strip-shaped member 110) come into contact with each other across the spiral gap C before the engagement between the engagement pin 14 and the engagement hole 24 is disengaged (see center of Figure 5(b)).

[0053] In other words, when an external force (for example, see arrow AR1) is applied to the spiral winding telescopic shaft 100, this force is borne not only by the engagement between the engagement pin 14 and the engagement hole 24, but also by the contact between opposing strip materials (for example, the widthwise sides of the first strip member 110) across the spiral gap C (for example, the first gap C1) (see the graph at the far right of Figure 5(b)).

[0054] As a result, when an external force is applied to the spiral-wound telescopic shaft 100, the force F (see Figure 6) acting on the engagement pin 14 is reduced compared to when an external force is applied to the comparative example spiral-wound telescopic shaft 100A, and slippage between the engagement pin 14 and the engagement hole 24 is suppressed. Consequently, deflection of the spiral-wound telescopic shaft 100 is suppressed, and the first and second problems described above are solved.

[0055] Next, we will describe an example configuration for solving the third problem mentioned above.

[0056] The total deflection B of the spiral-wound telescopic shaft 100 until opposing strip members (for example, the widthwise sides of the first strip member 110) come into contact with each other across a spiral gap C is expressed by the following equation 2, which is obtained by multiplying the spiral gap C by the number of turns (L / W). For simplification, instead of the gap C formed by actually winding the material spirally, the gap C × cosθ formed between cylinders by stacking cylinders in their axial direction is used. In this case, since θ ≈ 0, it is simplified to cosθ = 1. However, θ is the winding lead angle.

[0057] B=(W×C) / D×L / W=L×C / D (Formula 2) Note that (W×C) / D×L represents the amount of deflection per turn, and L / W represents the number of turns.

[0058] Here, we will explain the conditions for preventing the telescopic device 60 from tipping over. Figure 7 is a diagram illustrating the conditions for preventing the telescopic device 60 from tipping over. In Figure 7, the rectangle B2 drawn with a dotted line represents the spiral-wound telescopic shaft 100 before deflection. The arrow indicated by the symbol AR1 represents the external force applied to the spiral-wound telescopic shaft. The symbol L represents the total length of the spiral-wound telescopic shaft. The symbol D represents the diameter of the spiral-wound telescopic shaft. The symbol B represents the amount of deflection of the spiral-wound telescopic shaft.

[0059] To prevent the telescopic device 60 from tipping over, it is desirable that the spiral gap C is set such that, when an external force (for example, see arrow AR1) is applied to the spiral-wound telescopic shaft 100 and the tip of the spiral-wound telescopic shaft 100 is displaced relative to the base end, causing the spiral-wound telescopic shaft 100 to bend, the center of gravity CG (see Figure 7) of the product (for example, the spiral-wound telescopic shaft 100) exceeds the range of the lower mounting surface (see the range indicated by symbol E in Figure 7), that is, before it moves to the outside of the base end of the spiral-wound telescopic shaft 100 (see Figure 7), the opposing strip-shaped members (for example, the widthwise sides of the first strip-shaped member 110) across the spiral gap C come into contact with each other (see center in Figure 5(b)). To achieve this, it is desirable that the relationship between the amount of deflection B and the diameter D of the spiral-wound telescopic shaft 100 be: deflection B ≤ diameter D ... (Equation 3). The tipping limit deflection is L × D / (L 2 +D 2 ) 1 / 2 However, this value L × D / (L 2 +D 2 ) 1 / 2 Since is a value slightly smaller than D (i.e., L × D / (L 2 +D 2 ) 1 / 2 (Since ) ≈ D), in the above equation 3, L × D / (L 2 +D 2 ) 1 / 2 D is used instead of ). Note that the center of gravity CP in Figure 7 may be the common center of gravity of the spiral winding telescopic shaft 100 and the heavy object (the heavy object placed on the upper part of the spiral winding telescopic shaft 100 and shifted horizontally from the axis CX).

[0060] From equations 2 and 3 above, we obtain equation 4.

[0061] C≦D 2 / L...(Formula 4) For example, if the allowable deflection of the spiral-wound telescopic shaft 100 is 100 mm, the total length is 3000 mm, and the pitch is 44 mm, the number of turns will be 68 (1000 / 44 ≈ 68), and the allowable deflection per spiral turn will be 1.47 mm (100 / 68 ≈ 1.47).

[0062] If the shaft diameter is 100 mm, then if the spiral gap C is 3.34 mm or less, the deflection will not exceed the outer diameter, and the risk of tipping over will be reduced. The spiral gap C = 3.34 mm can be calculated using the above formula 2, where B = 100 mm (allowable deflection), L = 3000 mm (total length), and D = 100 mm (outer diameter).

[0063] On the other hand, if there is a heavy object such as a strip feeder (for example, a guide section 30, a guide member 32, a drive section 40) below the spiral winding telescopic shaft 100, and the center of gravity is lower, then C may be larger than described above.

[0064] As described above, according to this embodiment, deflection of the spiral-wound telescopic shaft 100 when an external force is applied to the spiral-wound telescopic shaft 100 can be suppressed. This is because, when an external force is applied to the spiral-wound telescopic shaft 100, the force is borne not only by the engagement between the engagement pin 14 and the engagement hole 24, but also by the contact between opposing strip-shaped members (for example, the widthwise sides of the first strip-shaped member 110) that are separated by a spiral gap C (for example, the first gap C1).

[0065] The numerical values ​​shown in the above embodiments are all examples, and it goes without saying that other appropriate numerical values ​​can be used.

[0066] The embodiments described above are merely illustrative in all respects. The invention is not to be construed as being limited by the descriptions of the embodiments above. The invention can be carried out in various other ways without departing from its spirit or main features. [Explanation of symbols]

[0067] 10...First housing section, 11...First strip-shaped member, 12...First flat strip section, 14...Engaging pin, 16...Weld mark, 20...Second housing section, 21...Second strip-shaped member, 22...Second flat strip section, 24...Engaging hole, 30...Guide section, 32...Guide member, 40...Drive section, 50...Cap section, 60...Telescopic device (helical reciprocating device), 70...Die, 71...Punch, 72...Punch, 73...Punch, 100...Helical winding type telescopic shaft (cylindrical extension) (Shrinkable body), 110...First strip-shaped member (first strip material), 111...First flat strip portion, 111i...Inner surface, 111o...Outer surface, 112...First engaging portion, 114...First hollow projection (engaging projection), 116...Opening, 118...Hole, 120...Second strip-shaped member (second strip material), 121...Second flat strip portion, 122...Second engaging portion, 124...Second hollow projection portion, 126...Opening, 210...First strip-shaped member, 211...First flat strip portion, 212...First section Joint part, 214...First hollow projection part, 216...Top part, 310...First strip-shaped member, 311...First flat strip part, 312...First engaging part, 314...First hollow projection part, 316...Top part, 318...Notch, 400...Spiral winding type telescopic shaft, 410...First strip-shaped member, 411...First flat strip part, 412...First engaging part, 414...First hollow projection part, 416...Opening, 420...Second strip-shaped member, 421...Second flat strip part, 422... Second engaging portion, 500... spiral winding type telescopic shaft, 510... first strip member, 511... first flat strip portion, 512... first engaging portion, 514... first hollow projection portion, 516... opening, 520... second strip member, 521... second flat strip portion, 522... second engaging portion, 524... peripheral portion, CX... axis, C1... first gap, C2... second gap, L1... first row of engaging projections, L2... second row of engaging projections, L3... first row of engaging portions, L4... second row of engaging portions

Claims

1. A spiral extension and retraction device is formed by spirally overlapping and winding a first strip and a second strip, which is positioned inside the first strip, around a common axis, with the strips offset from each other in the axial direction, thereby forming a cylindrical expandable body. The first strip material comprises a first row of engaging protrusions and a second row of engaging protrusions arranged in its longitudinal direction and composed of a plurality of engaging protrusions convex toward the axis, and is wound in a spiral shape while forming a spiral first gap. The second strip material comprises a first row of engaging portions and a second row of engaging portions, each composed of a plurality of engaging portions arranged in its longitudinal direction, and is wound in a spiral shape while forming a spiral second gap. The engagement portion is configured such that the engagement projection can engage with the first strip material and the second strip material in a spiral manner when they are wrapped around each other. When an external force is applied to the tip of the cylindrical expandable body in a direction perpendicular to the axis, causing the tip of the cylindrical expandable body to be displaced relative to the base end, the entire cylindrical expandable body is deflected, and at least one of the first gap and the second gap is set such that at least one of the first strip materials facing each other across the first gap and the second strip materials facing each other across the second gap come into contact with each other before the engagement between the engaging portion and the engaging projection disengages. A spiral reciprocating device in which, when the tip of the cylindrical expandable body is displaced relative to the base end, the amount of deflection when the cylindrical expandable body is deflected is B, the first gap is C1, the second gap is C2, and the diameter of the cylindrical expandable body is D, at least one of C1 and C2 is set such that B ≤ D.

2. The spiral reciprocating device according to claim 1, wherein when an external force is applied to the cylindrical expandable body and the tip of the cylindrical expandable body is displaced relative to the base end, causing the cylindrical expandable body to bend, at least one of the first strip material members facing each other across the first gap and the second strip material members facing each other across the second gap are set to come into contact with each other before the center of gravity of the cylindrical expandable body moves to the outside of the base end of the cylindrical expandable body.

3. The aforementioned external force is caused by placing a heavy object on the upper part of the cylindrical expandable body at a position shifted from the axis, The spiral reciprocating device according to claim 2, wherein the center of gravity is the common center of gravity of the cylindrical expandable body and the heavy object.

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