JP6554437B2 - Robot arm - Google Patents

Description

  The present invention relates to a robot arm.

Conventionally, various industrial robots have been active in industrial product manufacturing sites.
This type of robot is usually provided with a robot hand for performing actual work and a robot arm for guiding the robot hand to a predetermined position.
In addition, as such an industrial robot, for example, as disclosed in Patent Document 1, a robot hand is a simple chuck and a robot arm is a simple swing arm. Various things are known, such as those having a three-dimensional and complicated movement.

Industrial robots of this type are required to reduce the weight of components such as robot arms in order to reduce the power load.
A general robot arm is formed of a metal square pipe or the like.
However, due to the above demand, a robot arm having a structure in which a core formed of a resin foam is covered with a skin formed of a fiber reinforced resin material (FRP) may be used instead of a metal arm. ing.

Japanese Patent Laid-Open No. 2005-161688

If the weight of the robot arm is reduced, not only the energy required for operating the robot can be reduced, but also the speed of movement of the robot hand can be increased, and an improvement in work speed can be expected.
Moreover, the robot arm provided with the outer skin formed of the fiber reinforced resin material is superior in vibration damping properties compared to the metal robot arm.
The vibration controllability of the robot arm is an important factor in increasing the working speed of the industrial robot as well as increasing the speed of the robot arm.
In other words, industrial robots may not have sufficient vibration accuracy of the robot arm because there is a risk that the position accuracy of the robot hand may not be sufficient unless the robot arm vibrations have settled after the robot hand is guided to a predetermined position. It is important to improve the speed.
Therefore, although there is a strong demand for improvement in the damping property also for a robot arm provided with an outer shell formed of a fiber reinforced resin material, such a demand can not be sufficiently satisfied.

That is, the conventional robot arm has a problem that it is difficult to sufficiently satisfy the demands for light weight and vibration control.
An object of the present invention is to solve such a problem, and to provide a robot arm that is excellent in lightness and vibration control.

  The present inventor has intensively studied to solve the above-mentioned problems, and as a result, the core material of the robot arm is formed of an acrylic resin foam and the outer skin is formed of a fiber reinforced resin material containing carbon fiber and resin The inventors have found that the robot arm can exhibit excellent damping performance and lightness, and the present invention has been completed.

  That is, the present invention relating to a robot arm for solving the above problems is a robot arm comprising a core material and an outer skin covering the core material, wherein the outer skin includes a carbon fiber and a resin. The core material is formed of an acrylic resin foam.

The robot arm according to the present invention includes a core material formed of an acrylic resin foam and an outer skin covering the core material, and the outer skin is formed of a fiber reinforced resin material containing carbon fibers and a resin.
Therefore, according to the present invention, it is possible to provide a robot arm that is excellent in lightness and vibration control.

It is a typical top view of a robot arm concerning one embodiment of the present invention. It is a typical front view of the robot arm concerning one embodiment of the present invention. It is the II sectional view taken on the line of FIG. It is a typical partially cutaway sectional view of a robot arm of a 2nd embodiment. It is a typical top view of the robot arm of a 3rd embodiment. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5. It is a typical sectional view of the robot arm of a 4th embodiment. It is a typical sectional view of the robot arm of a 5th embodiment.

  The robot arm according to the first embodiment of the present invention will be described below.

FIG. 1 is a schematic plan view of a robot arm according to the present embodiment.
FIG. 2 is a schematic front view of the robot arm according to the present embodiment.
3 is a cross-sectional view taken along the line II of FIG.

As shown in FIGS. 1 and 2, a robot arm 1 according to the present embodiment is a robot arm that is used by being attached to a rotary shaft of an industrial robot drive device, and has a mounting portion 1 a attached to the rotary shaft as a longitudinal axis. It is provided on one end side in the direction (hereinafter also referred to as “base end side 1 s”).
That is, the robot arm 1 according to the present embodiment is attached to a driving device so as to be rotatable around a rotation center axis at one end portion in the longitudinal direction.
The robot arm 1 includes an arm main body portion 1b extending from the attachment portion 1a, and a robot hand is disposed on the other end side in the longitudinal direction opposite to the attachment portion 1a (hereinafter also referred to as “tip side 1t”). Is further provided with a hand mounting portion 1c.

As shown in FIG. 3, the robot arm 1 includes a core 11 and an outer cover 12 covering the core.
That is, the core material 11 is in contact with the outer skin 12 from the inside to support the outer skin 12 from the inside.

The attachment portion 1a and the hand mounting portion 1c are formed only by a fiber reinforced resin material forming the outer skin 12.
On the other hand, the arm main body 1b includes a core 11 formed of a resin foam inside the outer skin 12 as shown in FIG.

In the robot arm 1 of the present embodiment, the core material 11 is formed of an acrylic resin foam, and the outer skin 12 is formed of a fiber reinforced resin material (CFRP) containing carbon fibers and a resin.
Therefore, the robot arm 1 is excellent in lightness and strength.

In the arm main body 1b, the thickness of the outer skin 12 is substantially constant.
That is, the core material 11 in the present embodiment is one thickness thinner than the arm body 1 b.
The acrylic resin foam forming the core material 11 is usually harder than a polyolefin resin foam or the like.
By using such a relatively hard foam as a core material, the robot arm 1 of the present embodiment exhibits excellent vibration damping properties.
In this regard, first, a vibration generation mechanism will be described.
In the robot arm 1 of the present embodiment, for example, when the robot hand is attached and the robot arm 1 is attached to the drive device and operated, vibration occurs at a time when the rotating state is changed to the stopping state.
For example, when the robot arm 1 is operated to take out the parts stored in the parts tray with the robot hand and assemble them at a predetermined position of the product, the robot arm 1 is generated to stop the robot hand at the predetermined position of the parts tray or the predetermined position of the product. In response to the negative acceleration, a slight bending strain is generated in the robot arm 1 and a vibration is generated as the strain is recovered after stopping.
For this reason, even if the robot arm is lighter and capable of high-speed operation, it must wait for vibrations to settle before removing parts from the tray or assembling parts into the product. In some cases, sufficient effect for improving efficiency may not be exhibited.

As described above, since the acrylic resin foam is hard and has high strength, even if the robot arm 1 of the present embodiment is suddenly stopped from a state of high-speed operation, bending distortion hardly occurs.
In order to reliably exhibit such an effect by the robot arm 1, the acrylic resin foam forming the core material 11 preferably has a bending elastic modulus of 5 MPa or more.
In addition, the bending elastic modulus of an acrylic resin foam can be calculated based on the method described in JIS K7221-1.
Specifically, the flexural modulus can be measured from a core material by cutting out a rectangular parallelepiped test piece having a size of 25 mm long × 130 mm wide × 20 mm thickness and using the test piece.
The bending elastic modulus can be obtained by cutting out a rectangular parallelepiped test piece that is as large as possible and having a shape similar to that of the size if it is impossible to cut out the size of the core material.
The measurement was performed after holding the test piece in an environment of a temperature of 23 ± 2 ° C. and a relative humidity of 50 ± 5% for 16 hours or more and then in an environment of a temperature of 23 ± 2 ° C. and a relative humidity of 50 ± 5%. To implement.
At this time, the distance between supporting points is 100 mm, the test speed is 10 mm / min, and the tip of the test jig is 5R.
For the measurement, a testing machine commercially available from Orientec as a Tensilon universal testing machine (trade name “UCT-10T”) can be used.
As data processing software, for example, one marketed by Soft Brain under the trade name "UTPS-237S" can be used.

The acrylic resin foam may not be isotropic in bending elastic modulus depending on the manufacturing method.
In that case, it is preferable that the acrylic resin foam which forms the said core material 11 exhibits the bending elastic modulus of 5 Mpa or more in at least one direction.
The acrylic resin foam preferably has a flexural modulus of 5 MPa or more in the direction in which the arm main body 1b bends (longitudinal direction of the robot arm 1).
That is, it is preferable that the bending elastic modulus obtained by sampling the test piece so that the lateral direction is the longitudinal direction of the robot arm 1 is 5 MPa or more.
The acrylic resin foam preferably has a flexural modulus of 5 MPa or more in a direction (width direction of the robot arm 1) orthogonal to the direction in which the arm main body 1b bends.
And it is preferable that the acrylic resin foam has a flexural modulus of 5 MPa or more in all directions.
Note that the acrylic resin foam preferably has an upper limit of 200 MPa in bending elastic modulus in order to achieve both lightness and bending elastic modulus.
The flexural modulus of the acrylic resin foam is more preferably 10 MPa or more and 150 MPa or less, and particularly preferably 10 MPa or more and 130 MPa or less.

By forming the core material 11 from the acrylic resin foam having such characteristics, the robot arm 1 of the present embodiment is less likely to vibrate even if it is suddenly stopped from a high-speed operation state.
Further, in the robot arm 1 of the present embodiment, since the core material 11 is formed of an acrylic resin foam, even if vibration occurs, the vibration energy can be quickly absorbed by the core material.
The vibration of the robot arm 1 is mainly caused by strain energy stored in the shell 12 at the time of rapid stop.
In the robot arm 1 of the present embodiment, this vibration is propagated through the core material through the bubble film of the acrylic resin foam.
That is, the strain energy stored in the outer skin 12 vibrates not only the outer skin 12 but also the bubble film of the core material 11.
The robot arm 1 of the present embodiment can diverge vibration energy to the outside as a sound wave by the bubble film, and can convert the vibration energy into heat energy or the like by the viscosity term of the acrylic resin constituting the bubble film.
Moreover, since the core material 11 is formed of a hard acrylic resin foam, the robot arm 1 of this embodiment can quickly propagate the vibration of the outer skin 12 to the entire core material.

The robot arm 1 normally vibrates more sharply at the distal end side 1t than at the proximal end side 1s.
For this reason, the apparent density of the core material is higher on the distal end side than on the proximal end side in rapidly oscillating the vibration from the extreme distal end side to the proximal end side to quickly converge the shaking of the robot hand. It is preferable.
Further, the core material 11 preferably has a higher apparent density at the portion closer to the interface with the outer skin 12 than at the center portion in order to quickly propagate the vibration of the outer skin 12 to the inside.
Further, the core material 11 preferably has an average bubble diameter smaller than that of the central portion in the vicinity of the interface with the outer skin 12 in order to quickly propagate the vibration of the outer skin 12 to the inside.

Specifically, in order to reduce the weight of the robot arm, the core material 11 preferably has a low apparent density as an overall average, and the apparent density is preferably less than 0.35 g / cm ^3. More preferably, it is less than 25 g / cm ³ .
On the other hand, in order to increase the strength of the robot arm, the apparent density of the entire core material is preferably more than 0.04 g / cm ³ .

The apparent density of the core material 11 can be measured by the following method.
That is, the apparent density is as follows. The core material is cut so that the bubble shape is not changed as much as possible, and a test piece is cut out. The test piece is in a state of JIS K7100: 1999 symbol 23/50, in a second grade environment for 16 hours. After the adjustment, the size and mass of the test piece can be measured and determined by the following formula.
In addition, "DIGIMATIC" CD-15 type | mold by Mitutoyo Corporation is used for the dimension measurement of a test piece.

Apparent density (g / cm ³ ) = 10 ³ × mass of specimen (g) / volume of specimen (mm ³ )

The ratio (E / D) of the flexural modulus (E: MPa) to the apparent density (D: g / cm ³ ) is treated as an index indicating that the core material 11 has excellent strength while being lightweight. be able to.
In the following, the index is also referred to as “specific strength” or the like.
The specific strength of the core material 11 is preferably 200 or more, more preferably 250 or more, and particularly preferably 350 or more.
In addition, although it is preferable that the core material 11 is excellent in specific strength, it is not necessary to have an excessively high specific strength.
Moreover, when trying to obtain the core material 11 that is particularly excellent in specific strength, there is a possibility that a special monomer may be used as a starting material or a special production facility may be used when producing an acrylic resin foam. .
Therefore, in order to make the core material 11 easy to manufacture, the specific strength of the core material 11 is preferably 2000 or less, more preferably 1500 or less, and particularly preferably 1200 or less.

The acrylic resin foam forming the core material 11 has a smaller average cell diameter and is in a dense foamed state, which is advantageous for exerting excellent strength in the arm main body 1b.
Specifically, the average cell diameter of the core material 11 is preferably less than 1.5 mm, and more preferably less than 1.0 mm.

The average cell diameter of the core material 11 can be calculated as follows.
That is, the acrylic resin foam is cut as much as possible so that the bubble shape is not changed, and a rectangular parallelepiped specimen is cut out, and one corner is randomly selected from the eight corners of the rectangular specimen. The average cell diameter of the acrylic resin foam can be determined by calculating the average cell diameter of the three surfaces constituting the corner and arithmetically averaging the average cell diameters of the three surfaces.
The average bubble diameter on each surface can be determined as follows.
First, the central portion of each surface is photographed at a magnification of 18 times using a scanning electron microscope (“S-3000N” manufactured by Hitachi, Ltd.), and an image of the photographed cut surface is printed on A4 paper.
Next, an arbitrary line segment (length: 60 mm) is drawn at six locations for each sheet, and the average chord length for each line segment is calculated from the number of bubbles overlapping the line segment by the following equation.
However, the line segment is drawn as much as possible so that the bubbles do not come into contact with only the contact point, and if the bubble comes into contact with only the contact point, it is included in the number of bubbles.

Average chord length (t) = length of line segment / (number of bubbles x photo magnification)

And bubble diameter _DL is computed by following Formula.

D _L = t / 0.616

And the arithmetic average value of the bubble diameter (D _L ) calculated | required for every line segment is calculated | required, and let this arithmetic average value be the average bubble diameter of each surface.

The average bubble diameter of the core material 11 at a portion close to the interface with the outer skin 12 is a pair of test pieces that are cut out in a cube shape having a side of about 10 mm from the vicinity of the interface and facing each other in the cube. The test piece can be cut out so that one of the faces (two faces) is substantially parallel to the interface, and the measurement can be performed.
However, one of the three surfaces to be measured is the surface closest to the interface substantially parallel to the interface.

It is preferable that the acrylic resin foam which comprises the said core material 11 has high closed cell property from an intensity | strength surface.
The open cell ratio of the acrylic resin foam is preferably less than 50%, more preferably less than 25%, and particularly preferably less than 15%.

  The open cell rate of the acrylic resin foam can be measured by a 1-1 / 2-1 atmospheric pressure method in accordance with ASTM D-2856-87.

It is preferable that the acrylic resin forming the core material 11 has a loss coefficient (tan δ) of a certain value or more in order for the robot arm 1 to exhibit high vibration damping properties.
Specifically, in the acrylic resin, tan δ measured at 25 ° C. is preferably 0.05 or more, and more preferably 0.1 or more.
Note that the upper limit of tan δ of the acrylic resin is usually about 0.3.

The acrylic resin has a loss factor of 25 mm in length and 10 mm in width taken from the non-foamed sheet having a thickness of about 0.5 mm by, for example, hot pressing the acrylic resin foam forming the core material 11. It can be determined by strip-shaped samples.
Specifically, the strip sample is set on a viscoelastic spectrometer (for example, EXSTAR DMS6100, manufactured by SII Nanotechnology), frequency 1 Hz, chuck interval 10 mm, strain amplitude 5 μm, minimum tension / compression force. The dynamic viscoelasticity measurement is performed under the conditions of 50 mN, tension / compression gain 1.8, and force amplitude initial value 50 mN, and the storage elastic modulus (E ′) and loss elastic modulus (E ″) are obtained. Tan δ can be calculated from “/ E ′).

The acrylic resin forming the acrylic resin foam is a copolymer of an acrylic monomer and an aromatic vinyl monomer in that it is easy to impart the above-described preferable properties to the acrylic resin foam. Is preferred.
Examples of the acrylic monomer include (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, lauryl (meth) acrylate, and (meth) acrylic acid 2- Ethylhexyl, cyclohexyl (meth) acrylate, (meth) acrylamide, benzyl (meth) acrylate, maleic anhydride, maleic acid, fumaric acid, itaconic acid, itaconic anhydride, crotonic acid, maleic amide, maleic imide, etc. Can be mentioned.
Examples of the aromatic vinyl monomer include styrene and methylstyrene.

Among them, the acrylic resin contains methyl methacrylate, (meth) acrylic acid, and styrene as monomer units, and optionally contains one or both of maleic anhydride and methacrylamide as the monomer units, and It is preferable to contain monomer units in the following proportions.

(A) Methyl methacrylate: 35 to 70% by mass
(B) (Meth) acrylic acid: 14 to 45% by mass
(C) Styrene: 10 to 20% by mass
(D) Maleic anhydride: 0 to 10% by mass
(E) Methacrylamide: 0 to 10% by mass

The acrylic resin foam can be obtained, for example, by foaming a polymer obtained by polymerizing a polymerizable solution containing the monomers in the proportion as described above with a polymerization initiator with a foaming agent.
In this specification, the term “(meth) acryl” is used to mean both “acryl” and “methacryl”.
Therefore, the above “(meth) acrylic acid: 14 to 45% by mass” means “when both the acrylic acid and methacrylic acid are included and the total content thereof is 14 to 45% by mass”, “methacrylic acid”. In the case where the content of acrylic acid is 14 to 45% by mass, and the case where the content of acrylic acid is not 14% to 45% by mass is included. It is.

Examples of the polymerization initiator include redox polymerization initiators such as t-butyl hydroperoxide.
As said foaming agent, thermal decomposition type foaming agents, such as urea, are mentioned, for example.
Moreover, for the formation of the acrylic resin foam, a plasticizer, a dehydrating agent, a reducing agent and the like can be appropriately contained in the polymerizable solution.

On the other hand, the outer skin 12 is formed of a sheet-like fiber reinforced resin material, and includes a resin and a fiber (reinforced fiber) having a higher tensile breaking strength than the resin.
The fiber-reinforced resin material forming the outer cover 12 may include reinforcing fibers in the form of short fibers, but it is preferable to include reinforcing fibers as a sheet in which continuous fibers are woven.
The sheet made of the reinforcing fibers can be, for example, a plain woven fabric, a twill woven fabric, a satin woven fabric, or the like made of the continuous fibers.
Further, the sheet may be called a carbon UD (Uni Directional) or the like in which fibers are aligned in one direction.

Here, the shell 12 may be formed of a plurality of fiber-reinforced resin materials, but in that case, at least one or more of the fiber-reinforced resin materials have carbon fibers as the reinforcing fibers and the strength excellent for the robot arm 1 And it is important in exerting lightness and it is preferable that all reinforcing fibers are carbon fibers.
The fiber reinforced resin material may contain a plurality of types of reinforcing fibers.
When a plurality of fiber reinforced resin materials are overlapped to form the outer skin 12 in a laminated structure, a fiber reinforced resin material containing carbon fibers as reinforcing fibers and the reinforcing fibers are fibers other than carbon fibers. You may overlap a fiber reinforced resin material.
Examples of fibers other than the carbon fibers include glass fibers, aramid fibers, polyvinyl alcohol fibers, vinyl chloride fibers, acrylic fibers, polyester fibers, polyurethane fibers, polyethylene fibers, polypropylene fibers, polystyrene fibers, acetate fibers, and the like.

The resin (matrix resin) to be impregnated into the reinforcing fiber may be either a thermoplastic resin or a thermosetting resin.
Examples of the thermoplastic resin include thermoplastic resins such as polyethylene resin, polypropylene resin, polystyrene resin, polybutadiene resin, styrene butadiene resin, polyacetal resin, polyamide resin, and polycarbonate resin.
In the case of a thermosetting resin, an unsaturated polyester resin, an acrylic resin, a vinyl ester resin, an epoxy resin, a urethane resin, a phenol resin, a silicon resin, and the like can be given.

From the viewpoint of efficiently transmitting vibration to the core material 11, the outer skin 12 is preferably adhered to the core material 11 by its own matrix resin rather than being adhered to the core material 11 by an adhesive or the like.
In addition, in order to exhibit excellent adhesiveness between the outer skin 12 and the core material 11, the core material 11 is produced by cutting an acrylic resin foam larger than the core material 11. It is preferable.
The acrylic resin foam is normally in a state where the entire surface is covered with a cell membrane in a state of being produced by in-mold molding.
On the other hand, when such an acrylic resin foam is cut, a large number of air bubbles are opened on the cut surface.
The core material 11 exhibits an excellent anchoring effect when the core material 11 is bonded to the outer skin 12 by opening bubbles on the surface thereof.
That is, when the core material 11 is bonded to the outer skin 12 by using the adhesive force of the matrix resin of the fiber reinforced resin material forming the outer skin 12, for example, The adhesiveness between the outer skin 12 and the outer skin 12 can be exhibited.
The expression of such an anchor effect can also be exhibited when the core material 11 and the outer skin 12 are bonded with an adhesive without using the matrix resin of the fiber reinforced resin material.

Next, a method for manufacturing such a robot arm 1 will be described.
In this embodiment, prior to the manufacture of the robot arm 1, an acrylic resin foam that is a material for forming the core material 11 is prepared.
Here, first, a polymerizable solution containing an acrylic monomer, a polymerization initiator, a foaming agent (urea), a reducing agent, and the like is prepared.
More specifically, it contains methyl methacrylate, (meth) acrylic acid, and styrene, and optionally contains one or both of maleic anhydride and methacrylamide, and the proportion of each monomer in all monomers The following (A) to (E) are prepared, and a polymerizable solution containing substantially no polymerizable monomer other than the following (A) to (E) (for example, less than 1% by mass) is prepared.

(A) Methyl methacrylate: 35 to 70% by mass
(B) (Meth) acrylic acid: 14 to 45% by mass
(C) Styrene: 10-20 mass (D) Maleic anhydride: 0-10 mass%
(E) Methacrylamide: 0 to 10% by mass

The polymerizable solution is then heated at a temperature below the thermal decomposition temperature of urea to polymerize the monomers to obtain a polymer.
The polymer is heated to a temperature equal to or higher than the thermal decomposition temperature of urea and foamed to prepare an acrylic resin foam.
The acrylic resin for molding this acrylic resin foam does not substantially contain anything other than (A) to (E) in the monomer units contained, and (A) to (E) in the above ratio Since it contains, it becomes the thing excellent in intensity.
In producing an acrylic resin foam excellent in strength, the content of monomer units other than (A) to (E) in the acrylic resin is preferably 10% by mass or less, and is preferably 5% by mass or less. More preferably, the content is 1% by mass or less.
And the said core material 11 can cut and produce this acrylic resin foam.

Thereafter, in order to produce a robot arm using the cut foam, a pair of molds is prepared in which an internal space corresponding to the shape of the robot arm is formed when the mold is closed.
First, a liquid or gel-like coating material is applied to the molding surfaces of a pair of molding dies, and stretched with a roller so that air does not enter the molding surfaces.
Next, the outer skin is formed on the mold on one side.
In the present embodiment, as an example, the outer skin is molded by a hand lay-up molding method.
Specifically, in order to form a fiber-reinforced resin material constituting an outer shell, a reinforcing fiber sheet is disposed in a mold, and the reinforcing fiber sheet is impregnated with a thermosetting resin to be a matrix resin.
Furthermore, the process of arrange | positioning a fiber sheet and impregnating a thermosetting resin similarly is repeated 4 times, and the laminated structure by a some fiber reinforced resin material is formed in the thickness direction of an outer_layer | skin.

The same operation is performed for the mold on the other side.
At this time, when a fiber reinforced resin material using a thermosetting resin or a thermoplastic resin is used as the matrix resin, the mold may be appropriately heated.
In the case of using a reaction-hardening resin of a type that cures at room temperature as the matrix resin, heating of the mold is not particularly required.
In this embodiment, the outer skin is impregnated with a thermosetting resin every time the reinforcing fiber sheet is laid one layer at a time. However, if air hardly remains in the reinforcing fiber sheet, a plurality of reinforcing fibers are used. After laminating the fiber sheet, the thermosetting resin may be impregnated at a time.

In addition, after the forming material of the outer shell is accommodated in the forming die, if necessary, the forming material placed in the forming die may be pressurized in the thickness direction to form the outer shell.
In that case, excess resin can be eliminated by pressurization, and the outer skin can be made high in strength.
When forming an outer shell having excellent strength by applying the pressure, for example, another mold having a convex portion corresponding to the concave shape of the molding die is fitted into the molding die containing the forming material, and two molds are fitted. What is necessary is just to pressurize the material between them.
Moreover, the said pressurization can also be implemented by the autoclave method, without using another type | mold.
Examples of the autoclave method include the following methods.

(Method of producing outer skin by autoclave method)
A fiber reinforced resin material provided with a plain weave carbon fiber sheet is disposed so as to be in contact with the molding surface of the mold, and a plurality of (for example, five layers) fiber reinforced resin materials having a carbon UD supporting the resin are laminated, The laminate is made on the molding surface.
Here, such a laminate is used as an outer skin forming material.
A release film having a through hole (for example, product name “WL5200B-P” manufactured by AIRTECH) and a breather cloth (for example, product name “AIRWEAVE N4” manufactured by AIRTECH) so as to cover the entire mold. Are sequentially stacked.
The release film is formed of, for example, a tetrafluoroethylene-ethylene copolymer film, and has a large number of through-holes that can penetrate between both surfaces and allow the resin that exudes from the skin forming material to pass therethrough. Can be used.
The breather cloth can be formed of, for example, a nonwoven fabric made of polyester resin fibers and can be impregnated with the resin.
Cover the breather cloth with a bagging film (for example, product name “WL7400”, manufactured by AIRTECH), and sealant tape (for example, AIRTECH) with a sealing material between the outer peripheral edge of the bagging film and the mold facing the bagging film. The outer shell forming material is sealed with a bagging film by airtight bonding using a product name “GS43MR”).
As the bagging film, for example, one made of a polyamide resin film can be used.
The bagging film may be a part of which a back valve (for example, product name “VAC VALVE 402A” manufactured by AIRTECH) is arranged.

Next, the mold is fed into an autoclave, the back valve is connected to a vacuum line, and the pressure is reduced to, for example, 0.10 MPa.
This depressurization is continued after that.
Thereafter, while the air present in the skin forming material is sucked and removed, the inside of the autoclave is heated to 90 ° C., for example, at a temperature rising rate of 4 ° C./min. It heated over 90 minutes so that it might become (degreeC) (preheating process).

Thereafter, the inside of the autoclave is pressurized to, for example, a gauge pressure of 0.1 MPa to apply a pressing force to the outer skin forming material, and the temperature inside the autoclave is increased to, for example, 130 ° C. at a rate of temperature increase of 4 ° C./min. Then, heating is performed for 60 minutes so that the skin forming material becomes 130 ° C.
Thereafter, the inside of the autoclave is cooled. For example, when the inside of the autoclave reaches 60 ° C., the pressure inside the autoclave is released to return to atmospheric pressure, the outer skin is taken out, and cooled to room temperature.
By such an operation, an outer skin having a shape obtained by dividing the robot arm in half can be obtained.
The other half can be produced in the same manner, and the two obtained can be combined to form the outer skin of the robot arm.

(Production of robot arm)
Place the hardened robot arm skin on the mold and place the adhesive after placing the foam.
After pasting the adhesive to the outer shell of the other mold, the two molds are closed and adhered.
At this time, unsaturated polyester resin or the like can be used as an adhesive for bonding the skin and the core material.
When producing a robot arm having excellent strength, the unsaturated polyester resin is preferably used in a state where it is impregnated into a fiber sheet. For example, a glass chopped mat having a basis weight of 380 g / m ² is impregnated into an outer skin and a core. It can be used for adhesion to materials.
Thereby, the robot arm 1 as shown in FIG. 1 can be produced.

As described above, the embodiment of the present invention has been described in detail. However, the specific configuration is not limited to this embodiment and examples, and there is a design change within a range not departing from the gist of the present invention. However, they are included in the present invention.
For example, the robot arm of the present invention can employ two types of foams as the core material, and an embodiment (second embodiment) as shown in FIG.
In addition, the robot arm of the present invention can be formed as an embodiment (third embodiment) as shown in FIGS. 5 and 6 by forming a groove for wiring an electric wire.
Furthermore, when forming the groove | channel for wiring an electric wire, the robot arm of this invention can also be made into embodiment (4th Embodiment) as shown in FIG.

Second Embodiment
As shown in FIG. 4, the robot arm 1 according to the second embodiment has a flat plate shape bent in a “<” shape like the robot arm 1 according to the first embodiment described above.
FIG. 4 is a partially cutaway cross-sectional view showing a state in which one side is halved in the central portion of the robot arm in the thickness direction (depth direction in FIG. 4) with the virtual line BL shown in the figure as a boundary. .
The robot arm 1 shown in FIG. 4 is used by being attached to the rotary shaft of an industrial robot drive device in the same manner as the robot arm shown in FIG. 1, and the mounting portion 1a attached to the rotary shaft is provided. It is provided on one end side in the longitudinal direction (base end side 1s).
The robot arm 1 includes an arm main body 1b extending from the mounting portion 1a, and a hand mounting portion 1c on which a robot hand is mounted on the other longitudinal end side (tip side 1t) opposite to the mounting portion 1a. Is also provided in common with the robot arm 1 according to the first embodiment.

The robot arm 1 has a through hole 1 h which penetrates the robot arm in the thickness direction in the mounting portion 1 a.
The through hole 1 h is provided in such a manner as to form a flat cylindrical hollow portion in the robot arm 1, and is provided so as to penetrate the outer skin 12 and the core material 11.
The robot arm 1 is provided with a cylindrical metal ring 13 having an outer diameter corresponding to the diameter of the through hole 1 h and having a height corresponding to the thickness of the robot arm, the metal ring 13 is fitted in the through hole 1h.
That is, the metal ring 13 is flush with the upper surface 1x and the lower surface 1y of the robot arm 1 and is fitted into the through hole 1h.
The metal ring 13 has a hollow portion 13a that penetrates the robot arm 1 up and down, and is used so that the rotation shaft of the driving device is inserted through the hollow portion.
Further, the outer peripheral surface 13 b of the metal ring 13 is bonded to the outer skin 12 and the core material 11 and integrated therewith.
The metal ring 13 is for fixing the robot arm 1 to the rotation shaft of the drive device, and the axis passing through the center C thereof is the rotation center axis CX of the robot arm 1.

  The core material is formed of a first foam 11a, which is the acrylic resin foam, and a second foam 11b having a higher flexural modulus than the first foam, and the first foam 11a is It extends from the other end side (distal end side 1t) to the one end side (proximal end side 1s) and is bonded to the metal ring via the second foam 11b.

The second foam 11b preferably has a flexural modulus that is twice or more that of the first foam 11a, more preferably has a flexural modulus of 20 MPa to 200 MPa, and a flexural modulus of 40 MPa to 150 MPa. It is further preferable to have
The bending elastic modulus of the second foam 11b can be obtained by the same method as the bending elastic modulus of the acrylic resin foam.

In the present embodiment, since the second foam 11b is interposed between the metal ring 13 and the acrylic resin foam, a high shear stress is generated between the metal ring and the core material when the robot arm is driven. Also in the outer peripheral surface of the metal ring, the core material can be inhibited from cohesive failure or interfacial peeling.
In order to exhibit such an effect more remarkably, it is preferable to roughen the outer peripheral surface of the metal ring before bonding to the core material or the outer skin.

Third Embodiment
When causing the robot hand to exhibit a power driving mechanism and a sensing function, it is preferable that the robot arm 1 can route electric wires for power transmission and signal transmission from the base end side 1s to the tip end side 1t.
In such a case, the robot arm 1 illustrated in FIGS. 5 and 6 can be preferably used.
The robot arm 1 illustrated in FIG. 5 has a wiring path 20 extending from the proximal side 1s to the distal side 1t.
The wiring path 20 in the present embodiment is a groove formed in the core material 11.
The robot arm 1 illustrated in FIG. 5 is provided with a mounting portion 1a attached to the rotating shaft on the proximal end side 1s and a hand mounting portion 1c on which the robot hand is attached on the distal end side 1t. This is the same as the robot arm 1 exemplified so far.

On the other hand, the robot arm 1 illustrated in FIG. 5 is different from the robot arm 1 illustrated so far in that the skin 12 covering the core member 11 has two openings.
All the openings of the outer skin 12 are opened on the upper surface 1x of the robot arm 1.
One of the two openings is for inserting an electric wire into the robot arm on the base end side 1 s of the robot arm 1, and the other is an electric wire inserted into the robot arm 1 t on the distal end side 1 t of the robot arm 1. In order to pull out the robot arm.
That is, the robot arm 1 of the present embodiment includes a wire insertion port 21 on the proximal end side 1s and a wire outlet 22 on the distal end side 1t.
Further, as shown in FIG. 6, the robot arm 1 of the present embodiment has an electric wire wiring groove 23 extending from the electric wire insertion port 21 to the electric wire outlet 22.
That is, the robot arm 1 of the present embodiment includes a wiring path 20 that extends from the wire insertion port 21 to the wire outlet 22 via the wire wiring groove 23.
The robot arm 1 of this embodiment is formed so that the electric wire CB can be wired along the wiring path 20.

The groove 23 in the present embodiment is formed by separating the core material 11 and the outer skin 12. Specifically, the core material 11 is recessed along the wiring path 20. Is formed by.
In the robot arm 1 of this embodiment, since the electric wire CB is protected by the outer skin 12, the electric wire CB collides with surrounding devices when the robot arm 1 is driven, or the electric wire coating is damaged. This can suppress the possibility of electric leakage.

Fourth Embodiment
In the third embodiment, the core 11 is recessed with respect to the outer skin 12 to form the groove 23 for receiving the electric wire CB. From the viewpoint of protecting the electric wire CB with the outer skin 12, FIG. As shown in FIG. 5, the outer skin 12 may be recessed with respect to the boundary surface with the core member 11 to form the groove 23, and the electric wire CB may be accommodated in the groove 23.
Further, the groove 23 may be formed by recessing both the core material 11 and the outer skin 12 in directions away from each other, if necessary.

Fifth Embodiment
In the third and fourth embodiments, the wiring path 20 is provided by forming a groove between the outer skin 12 and the core material 11. However, the wiring path 20 has a wire insertion port 21 as shown in FIG. The through passage 24 may be provided between the wire and the wire outlet 22.
That is, when the electric wire CB is routed inside, it may pass between the core material 11 and the outer skin 12 or may pass through the inside of the core material 11.
The through-passage 24 may be formed by embedding a metal pipe such as aluminum or a resin pipe such as polyvinyl chloride in the core material, or simply having a cavity formed in the core material. May be.

  In addition to the above examples, the present invention can be further modified by adopting conventionally known technical matters relating to a robot arm, a fiber reinforced resin material, and an acrylic resin foam. Needless to say, it is a matter of course.

1: Robot arm, 1a: Mounting portion, 1b: Arm body portion, 1c: Hand mounting portion, 11: Core material, 12: Outer shell

Claims (4)

A robot arm comprising a core and an outer skin covering the core;
The outer skin is formed of a fiber reinforced resin material containing carbon fiber and resin;
The core material is formed of an acrylic resin foam,
A mounting portion to be attached to the rotation shaft is provided on one end side in the longitudinal direction, and a hand mounting portion to which the robot hand is attached is provided on the other end side in the longitudinal direction.
The one end side is provided with a through hole penetrating the outer skin and the core material, and a metal ring fitted to the through hole;
The metal ring is bonded to the outer skin and the core material;
The core material is formed of a first foam that is the acrylic resin foam and a second foam having a higher flexural modulus than the first foam,
The first foam is a robot arm that extends from the other end to the one end and is bonded to the metal ring via the second foam .   The robot arm according to claim 1, wherein the acrylic resin foam forming the core material has a bending elastic modulus of 5 MPa or more. The monomer unit of the acrylic resin forming the acrylic resin foam is
Including methyl methacrylate, (meth) acrylic acid, and styrene as essential components,
Contains maleic anhydride and methacrylamide as optional ingredients,
And the robot arm of Claim 1 or 2 which contains the said monomer unit in the ratio shown to following (A)-(E).
(A) Methyl methacrylate: 35 to 70% by mass
(B) (Meth) acrylic acid: 14 to 45% by mass
(C) Styrene: 10 to 20% by mass
(D) Maleic anhydride: 0 to 10% by mass
(E) Methacrylamide: 0 to 10% by mass Provided with wiring paths for the previous SL one end arranging the electric wire toward the other end,
The outer cover includes a wire insertion port at the one end side, and a wire outlet at the other end side,
The robot arm according to any one of claims 1 to 3 , wherein an electric wire wiring groove is provided between the electric wire insertion port and the electric wire drawing outlet. The electric wire wiring groove is formed by separating the core material and the outer skin. .

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