Arm-like structure and robot

Abstract

An arm-like structure (1) is provided with: a tubular main body portion (2); and a mounting interface portion (3) which is engaged with an end portion of at least one of the main body portion (2) and which is capable of being fixed to another component, at least a portion of the main body portion (2) and the mounting interface portion (3) being composed of a resin containing continuous reinforcing fibers, the main body portion (2) and the mounting interface portion (3) being engaged in a state in which relative movement in a longitudinal direction of the main body portion (2) and around a longitudinal axis is locked by fitting of a recess (8) provided in one of the main body portion (2) and the mounting interface portion (3) into a protrusion (10) provided in the other.

Description

Technical Field

[0001] This invention relates to arm-like structures and robots. Background Technology

[0002] As an arm for industrial robots, a structure is known in which, in order to achieve lightweight while maintaining strength, an interface is joined at both ends of a long, resin-made arm body using an adhesive (for example, see Patent Document 1).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2020-15127 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] Using adhesives only to join the arm body and mounting interface sometimes fails to achieve the same level of strength and rigidity required for applications like those in industrial robots. Therefore, an arm-like structure is desired that can be joined with high strength using a simple method, while still being suitable for applications requiring strength and rigidity.

[0008] Solution for solving the problem

[0009] One aspect of the present invention is an arm-shaped structure comprising: a tubular main body portion; and a mounting interface portion which engages with at least one end of the main body portion and is capable of being fixed to other components. At least a portion of the main body portion and the mounting interface portion are made of resin comprising continuous reinforcing fibers. The main body portion and the mounting interface portion are engaged to lock the main body portion in a state of relative movement along its long axis and about the long axis by fitting a recess provided on one side with a protrusion provided on the other side.

[0010] The definition of continuous reinforcing fibers here is generally that the length of the reinforcing fiber is 10 mm or more, and it is defined as a reinforcing fiber that is difficult to form in injection molding. The length of the reinforcing fiber contained in the resin particles used for injection molding is generally about 1 mm for short fibers and about 2 mm for long fibers. If the length is 10 mm or more, the reinforcing fiber will become entangled in the screw of the injection molding machine, becoming a major cause of damage to the injection molding machine. Attached Figure Description

[0011] Figure 1 This is a front view of an arm-shaped structure representing one embodiment of the present invention.

[0012] Figure 2 It means Figure 1 A longitudinal sectional view of the arm-shaped structure.

[0013] Figure 3 It means Figure 1 A partially enlarged longitudinal sectional view of the mounting interface of the arm-shaped structure.

[0014] Figure 4 It indicates composition Figure 1 A three-dimensional view of the main body of the arm-shaped structure and the reinforcing fibers of the mounting interface.

[0015] Figure 5 It indicates that it is used for manufacturing. Figure 1 A longitudinal sectional view of an example of a mold for an arm-shaped structure.

[0016] Figure 6 It means in Figure 1 An enlarged longitudinal sectional view of the state in which the resin injection port is pressed into the preform during the manufacturing process of the arm-shaped structure.

[0017] Figure 7 It means in Figure 1 An enlarged longitudinal sectional view of the state of the resin injection port separating from the preform during the manufacturing process of the arm-shaped structure.

[0018] Figure 8 It means Figure 1 A partial longitudinal sectional view of the mounting interface of the first modified example of the arm-shaped structure.

[0019] Figure 9 It means Figure 1 A partial longitudinal sectional view of the mounting interface of the second modified example of the arm-shaped structure.

[0020] Figure 10 It means Figure 1 A partial longitudinal sectional view of the mounting interface of the third modified example of the arm-shaped structure.

[0021] Figure 11 It means Figure 1 A partial longitudinal sectional view of the mounting interface of the fourth variant of the arm-shaped structure.

[0022] Figure 12 It means Figure 1 A partial longitudinal sectional view of the mounting interface of the fifth modified example of the arm-shaped structure. Detailed Implementation

[0023] Hereinafter, an arm-shaped structure 1 and a robot according to one embodiment of the present invention will be described with reference to the accompanying drawings.

[0024] The arm-like structure 1 in this embodiment is, for example, a robotic arm.

[0025] The robot of this embodiment has at least one arm-shaped structure 1.

[0026] like Figure 1 as well as Figure 2 As shown, the arm-shaped structure 1 of this embodiment includes: a cylindrical tubular main body 2 having an inner hole 2a; and a pair of mounting interface portions 3, which are engaged with the two ends of the main body 2 in the long axis direction.

[0027] The main body 2 is, for example, at least a portion of which is composed of carbon fiber reinforced resin (CFRP) containing continuous reinforcing fibers 30.

[0028] At least one part of the mounting interface part 3 is also made of carbon fiber reinforced resin containing continuous reinforcing fibers 30, and has a hollow part 4 connected to the inner hole 2a of the main body part 2.

[0029] Additionally, the mounting interface 3 is provided with an annular flange 5 for fixing to other components constituting the robot, such as the output shaft of a reducer. Each pair of flanges 5 of the mounting interface 3 has a flange surface 5a disposed on the same plane parallel to the long axis of the main body 2.

[0030] The flange portion 5 has a central hole 6 that opens the hollow portion 4, and a plurality of through holes 7 arranged circumferentially spaced around the central hole 6. Cables and other wires can be routed along the path of passing through the inner hole 2a of the main body portion 2 via the central hole 6 of one flange portion 5 and exiting through the central hole 6 of the other flange portion 5. To improve the appearance of the arm, the flange portion 5 is provided within the hollow portion 4, and the opening 11 is formed to a relatively large size to allow tools and human hands to enter.

[0031] In addition, the mounting interface 3 has a flat metal plate 41 embedded in the flange 5.

[0032] like Figures 1 to 3 As shown, the metal plate 41 is formed into an annular plate shape with a central hole 42. A plurality of through holes 43 are provided on the metal plate 41 at intervals along the circumference and extending along the thickness direction.

[0033] The metal plate 41 has its thickness-direction side as a mounting surface 41a, which is fully exposed. The other side of the metal plate 41 in the thickness direction is partially covered by the resin constituting the flange 5, with the area around several through holes 43 partially exposed within the through holes 7 of the flange 5. The surface of the metal plate 41 exposed around the through holes 43 serves as the contact surface for mounting screws (not shown) inserted into the through holes 43.

[0034] The main body 2 and a pair of mounting interface parts 3 are joined by the following structure.

[0035] That is, such as Figure 2 as well as Figure 3 As shown, the main body 2 has radially penetrating through holes (recesses) 8 at positions located at predetermined distances from both ends along the long axis. The through holes 8 have a circular cross-sectional shape and are provided in multiples, for example, four, at circumferential intervals near each end.

[0036] The mounting interface 3 is provided with: a cylindrical fitting part 9, which fits the outer peripheral surfaces of the two ends of the main body 2; and a complementary-shaped protrusion 10, which protrudes radially inward from the inner surface of the fitting part 9 and fits perfectly with the through hole 8 of the main body 2.

[0037] like Figure 4 As shown, in the orientation direction of the reinforcing fibers 30 within the resin constituting the main body 2 and the mounting interface 3, at least a portion of the reinforcing fibers 30 is oriented in a direction perpendicular to the shear direction of the through hole 8 and the protrusion 10. Specifically, at least a portion of the reinforcing fibers 30 is preferably oriented along the central axis direction of the inner surface of the through hole 8 and along the central axis direction of the outer peripheral surface of the protrusion 10.

[0038] The manufacturing method of the arm-shaped structure 1 of this embodiment, which is configured in this way, will be described below.

[0039] The arm-shaped structure 1 of this embodiment is manufactured by using the RTM (resin transfer molding) method, utilizing... Figure 5 The mold 100 shown is for molding resin.

[0040] The mold 100 includes: an upper mold 110 and a lower mold 120, which open and close in the vertical direction; a cylindrical first movable mold 125 supported in a manner that allows linear movement in the vertical direction; and a cylindrical second movable mold 130 supported in a manner that allows linear movement through the first movable mold 125 in the horizontal direction. The upper mold 110 includes a resin injection section 150 having a through hole 111 for injecting resin. The front end of the second movable mold 130 has a fitting protrusion 131 that can fit into the inner hole 2a of the main body 2 without gap.

[0041] In the manufacturing method of this embodiment, firstly, through holes 8 are formed near the ends of both sides of the main body 2. Additionally, a preform 31 is disposed inside the mold 100 as an intermediate substrate material. The preform 31 is in a state where it is pre-shaped into a product shape by continuous reinforcing fibers 30.

[0042] Since the reinforcing fibers 30 of the preform 31 have strong strength relative to all directions, for example, the orientation angles of the reinforcing fibers 30 of the preform 31 in one direction can be offset by 45 degrees and they can be arranged and overlapped into four layers. In addition, the smaller the angle is divided, the more directions can be strengthened.

[0043] Moreover, such as Figure 5 As shown, one end of the main body 2 is inserted from the horizontal direction and accommodated in the space formed between the upper mold 110 and the lower mold 120. At the same time, with the metal plate 41 installed at the front end of the first movable mold 125, the first movable mold 125 is inserted vertically from above, and the second movable mold 130 is inserted horizontally from the opposite direction to the main body 2, so that the fitting protrusion 131 fits into the inner hole 2a of the main body 2.

[0044] Thus, the cavity 140, which is equivalent to the mounting interface 3, is formed by the upper mold 110, the lower mold 120, the first movable mold 125, the second movable mold 130, and the outer surface of the main body 2.

[0045] Then, the resin injection section 150 of the upper mold 110 is moved into the mold 100, and the still soft preform 31 disposed inside the mold 100 abuts against the front end face of the resin injection section 150. Furthermore, as... Figure 6 As shown, the resin injection section 150 moves further into the mold 100, pressing the preform 31 into the through hole 8, thereby deforming the preform 31. Then, as... Figure 7 As shown, by slightly pulling the resin injection section 150 upward from the inside of the mold 100, the resin injection section 150 is separated from the preform 31, and molten resin P is injected into the cavity 140 through the through hole 111 provided in the resin injection section 150, thereby forming the mounting interface section 3 at one end of the main body section 2.

[0046] That is, the arm-shaped structure 1 is manufactured by embedding the main body 2 as an embedded part into the molded mounting interface 3.

[0047] The location of the through hole 111 is not limited to Figure 5 The location of the reinforcing fibers 30 within the resin should be considered, and they should be positioned optimally.

[0048] Alternatively, the metal plate 41 can also be used to form the mounting interface 3 while mounted on the lower mold 120.

[0049] If, during the molding process of the mounting interface portion 3, molten resin P is injected into the cavity 140, a cylindrical fitting portion 9, surrounding one end of the main body portion 2 in the long axis direction including the through hole 8, is formed at a position that is in close contact with the outer peripheral surface of the main body portion 2. At the same time, a portion of the molten resin P in the fitting portion 9 flows into the through hole 8 and extends radially inward from the inner surface of the fitting portion 9, forming a cylindrical protrusion 10 with a shape complementary to the through hole 8.

[0050] That is, in the arm-shaped structure 1 of this embodiment, the protrusion 10 formed when the molten resin P is injected is fitted into the through hole 8 formed in the main body 2. As a result, a pair of mounting interface portions 3 that are engaged with the two ends of the main body 2 can be fixed to the main body 2 in a state that restricts the relative movement of the main body 2 in the axial and circumferential directions, that is, in a state that locks the relative movement of the main body 2 in the direction of the long axis and around the long axis.

[0051] In other words, the main body 2 and the mounting interface 3 are engaged to lock the main body 2 in the long axis direction and in a state of relative movement around the long axis by fitting the protrusion 10 formed when the mounting interface 3 is formed with the through hole (recess) 8 of the main body 2.

[0052] Compared to the case where only adhesive is used to fix the main body 2 and the mounting interface 3, the joint strength in the shear direction can be improved by the fitting of the through hole 8 and the protrusion 10.

[0053] Furthermore, since the main body 2 and the mounting interface 3 are not integrally molded from resin, the mold 100 can be constructed more easily. In particular, since the elongated main body 2 is constructed as a metal tube, it has the following advantages: when molding the mounting interface 3, it is not necessary to place a core along the entire length of the main body 2, which makes it easy to manufacture.

[0054] Furthermore, since the second movable mold 130, which has a fitting protrusion 131 that fits into the inner hole 2a of the main body 2, closes the through hole 8 of the main body 2 from the inside, it is possible to prevent the molten resin P from leaking out of the main body 2.

[0055] In addition, a first movable mold 125 and a second movable mold 130 are provided that move relative to the upper mold 110 and lower mold 120, which open and close in the vertical direction. As a result, an opening 11 for operation, which communicates with the inner hollow part 4, can be formed in the mounting interface part 3 located in the path of the first movable mold 125 and the second movable mold 130.

[0056] Furthermore, according to this embodiment, since the mounting interface portion 3 is made of the same carbon fiber reinforced resin as the resin constituting the main body portion 2, the bonding strength can be improved by fusing the resins of the main body portion 2 and the mounting interface portion 3 together.

[0057] Furthermore, by oriented at least a portion of the reinforcing fibers 30 in a direction perpendicular to the shear direction of the through hole 8 and the protrusion 10, the strength relative to the shear force acting on the protrusion 10 along the axial or circumferential direction of the main body 2 can be significantly improved.

[0058] Furthermore, in this embodiment, the case of molding the mounting interface part 3 using the RTM (resin transfer molding) method is described as an example, but it is not limited to this.

[0059] For example, the mounting interface 3 can also be formed by using a compressive heating method, which involves heating, pressurizing, and vacuuming a sheet-like intermediate material called a preform material impregnated with resin in reinforcing fiber 30, to cure the resin.

[0060] Alternatively, the following VaRTM (vacuum-assisted resin transfer molding) method can be used: instead of using the upper mold 110, only the lower mold 120 is used, the upper surface is covered with a thin film seal, and the resin is impregnated by vacuum force instead of pressure.

[0061] Alternatively, the following pressure forming method can be used: the upper mold 110 and the lower mold 120 are closed, thereby applying pressure while simultaneously curing the preform and the SMC (sheet molding compound) matrix material. SMC (sheet molding compound), as a type of pressure forming, is a forming method in which overlapping sheet-like SMC matrix material is placed within the mold 100 and pressurized to flow; this forming method can also be used.

[0062] In either case, as long as the portion that becomes the protrusion 10 by molding is configured and formed with continuous reinforcing fibers 30 in a direction perpendicular to the shear direction applied to the protrusion 10, it is acceptable.

[0063] In this embodiment, the main body 2 is made of carbon fiber reinforced resin, but it is not limited to this. Metals such as aluminum alloy and magnesium alloy can also be used as the material for the main body 2. Alternatively, the main body 2 can be made of resin that does not contain the reinforcing fibers 30. Furthermore, the mounting interface 3 can be made of metal such as aluminum alloy or magnesium alloy and fixed to the mold 100 as a metal insert, while the main body 2 is molded from carbon fiber resin.

[0064] Furthermore, while a circular cross-section is used as an example for the through hole 8 provided in the main body 2, any cross-sectional shape can be used instead. The size of the cross-sectional shape is also arbitrary. To avoid stress concentration, a shape without sharp edges is preferred for both the through hole 8 and the protrusion 10.

[0065] Furthermore, it is sufficient to provide one or more through holes 8 in the main body 2. It is desirable to provide the main body 2 with a sufficient number of through holes to ensure that the fitting portion 9 will not detach or rotate even if the protrusion 10 or concave portion 12 is sheared. To ensure higher strength, multiple through holes 8 may also be evenly distributed on the circumference of the main body 2.

[0066] Furthermore, in this embodiment, the recess provided in the main body 2 is made into a through hole 8, but it is not limited to this, such as... Figure 8 As shown, a non-penetrating recess 12 extending radially inward from the outer periphery of the main body 2 can also be used. According to this structure, it is not necessary to use the second movable mold 130 to close the through hole 8, and the mold 100 can be made into a simpler structure.

[0067] The recess 12 can be recessed radially inward from the outer peripheral surface of the main body 2, or it can be recessed radially outward from the inner peripheral surface of the main body 2. When the recess 12 is provided on the inner peripheral surface, as... Figure 9 As shown, the fitting part 9 of the mounting interface part 3 can be formed into a cylindrical shape that fits into the inner circumferential surface of the main body part 2.

[0068] In addition, such as Figure 10 As shown, instead of the recess 12, a protrusion 13 extending radially along the outer or inner circumferential surface of the main body 2 can also be used. In this case, as... Figure 10 As shown, a recess 14 with a shape complementary to the protrusion 13 and accommodating the protrusion 13 is formed in the mounting interface portion 3.

[0069] In addition, such as Figure 11 As shown, the fitting portion 9 of the mounting interface portion 3 can also be a fitting portion having the following two shapes: an inner fitting portion 15, which fits into the inner peripheral surface of the main body portion 2; and an outer fitting portion 16, which fits into the outer peripheral surface. In this case, the protrusion 10 formed in the through hole 8 of the main body portion 2 is formed into a column shape connecting the inner fitting portion 15 and the outer fitting portion 16. As a result, the mounting interface portion 3 and the main body portion 2 can be joined more firmly.

[0070] In addition, such as Figure 12 As shown, other components (metal, fiber-reinforced resin, etc.) 20 that are different from the main body 2 and the mounting interface 3 can also be used as embedded components and fixed together with the main body 2 to the mold 100 to form the mounting interface 3.

[0071] Alternatively, although not shown in the figure, it can also be made into the following structure: on the inside of the main body 2, a reinforcing member with a through hole made of metal or fiber-reinforced resin is made into an embedded member together with the main body 2.

[0072] Furthermore, in this embodiment, an arm-shaped structure 1 with mounting interface portions 3 at both ends of the main body 2 is illustrated as an example. However, an arm-shaped structure with a mounting interface portion 3 at only one end can also be used. Additionally, a case with a flange portion 5 parallel to the long axis of the arm-shaped structure 1 is illustrated as an example. However, a case with a flange portion 5 extending in a direction intersecting the long axis of the arm-shaped structure 1 can also be applied. Furthermore, a robot arm is illustrated as the arm-shaped structure 1, but any other arm-shaped structure can also be applied.

[0073] Alternatively, the mounting interface portion 3 at both ends can be pre-formed in other processes, fixed to the injection molding mold on the side of the main body portion 2, and then the main body portion 2 and the mounting interface portion 3 can be integrated by injection molding.

[0074] In addition, the main body 2 is not limited to a straight cylindrical shape; it can be a shape in which the diameter increases towards both ends, or it can be a square tube shape.

[0075] Alternatively, the main body 2 or the mounting interface 3 formed of carbon fiber reinforced resin may contain a resin portion that does not contain the reinforcing fiber 30.

[0076] Furthermore, while carbon fiber reinforced resin has been used as an example, the reinforcing fiber 30 can be made not only of carbon fiber, but also of any material such as glass fiber or aramid fiber. Additionally, the base material resin can be either thermoplastic resin or thermosetting resin.

[0077] Furthermore, the mechanical strength of the connection formed by the fitting of the through hole 8 and the protrusion 10 is essentially determined by the shear strength. If a gap is generated between the through hole 8 and the protrusion 10, they will move relative to each other during use, deteriorating the positioning accuracy of the robot arm. Therefore, an adhesive can be used to fill the gap between the through hole 8 and the protrusion 10. Alternatively, an adhesive that completely fills the gap after being melted by heating can also be used.

[0078] The embodiments of the present invention have been described above, but those skilled in the art will understand that various modifications and alterations can be made without departing from the scope of the following claims. Furthermore, appropriate combinations of the embodiments described above, and implementations based on undescribed manufacturing methods, are also included within the scope of the present invention.

[0079] Explanation of reference numerals in the attached figures:

[0080] 1: Arm-shaped structure

[0081] 2: Main body

[0082] 2a: Inner hole

[0083] 3: Install the interface section

[0084] 8: Through hole (recess)

[0085] 9: Chimeric part

[0086] 10: convex part

[0087] 12: concave part

[0088] 13: convex part

[0089] 14: concave part

[0090] 15: Inner fitting part

[0091] 16: Outer fitting part

[0092] 30: Reinforcing Fibers

[0093] 100: Mold

[0094] 125: First movable mold (inner mold)

[0095] 130: Second movable mold (inner mold)

[0096] 140: Cavity

Claims

1. An arm-shaped structure, characterized in that, have: The tubular main body; and The mounting interface engages with at least one end of the main body and can be fixed to other components. At least a portion of the main body and the mounting interface are made of resin containing continuous reinforcing fibers. The main body and the mounting interface are engaged by the fitting of a recess on one side and a protrusion on the other side, thereby locking the main body in a state that prevents relative movement along its long axis and around that long axis. The area surrounding the recess and at least one of the protrusions are made of resin containing the reinforcing fibers. The fibers of at least a portion of the reinforcing fibers are oriented along the central axis of the inner surface of the recess and along the central axis of the outer peripheral surface of the protrusion.

2. The arm-shaped structure according to claim 1, characterized in that, At least a portion of the mounting interface is made of resin.

3. The arm-shaped structure according to claim 1, characterized in that, At least a portion of the main body is made of resin.

4. The arm-shaped structure according to any one of claims 1 to 3, characterized in that, The main body is embedded as an embedded component into the mounting interface portion.

5. A robot, characterized in that, The robot has at least one arm-like structure as described in any one of claims 1 to 4.

Images