JP6756371B2 - Drilling method, resist layer and fiber reinforced plastic - Google Patents

Description

The present disclosure relates to drilling methods, resist layers and fiber reinforced plastics.

Fiber reinforced plastic (FRP) is made of reinforced fibers (glass fiber, carbon fiber, aramid fiber, polyethylene fiber, silon fiber, boron fiber, etc.) and resin (polyester resin, vinyl ester resin, epoxy resin, phenol resin and thermoplastic resin). It is a composite material with improved strength, and is used in a wide range of fields such as daily necessities, sporting goods, automobiles, and aerospace industry applications.

The FRP may be punched or drilled to improve sound absorption. As a method of forming a hole in a work piece made of FRP, a drilling process using a drill and a sandblasting process are used. For example, Patent Document 1 describes that a resist layer having sandblast resistance is arranged on the surface of a work piece, and a region of the work piece that is not covered by the resist layer is removed by sandblasting.

Japanese Unexamined Patent Publication No. 2012-196751

Drilling using a drill is not preferable from the viewpoint of productivity because the machining time becomes long when the number of holes to be drilled is large. Further, in the drilling process using a drill, fluffing may occur around the holes formed in the workpiece, or peeling may occur on the surface of the workpiece.

Further, even when holes are formed in the work piece by sandblasting as in the method described in Patent Document 1, the degree of fluffing or peeling on the work piece is lower than that of drilling using a drill. May occur.

Therefore, it is required to form holes in the fiber reinforced plastic while suppressing the occurrence of fluffing and peeling.

In one aspect of the present disclosure, there is provided a drilling method for forming holes having a desired diameter in a work piece made of fiber reinforced plastic. This method involves arranging a resist layer having an opening having a diameter smaller than a desired diameter on the work piece, and exposing the work piece from the opening while cutting the peripheral edge of the opening of the resist layer. It includes a step of injecting a propellant onto a work piece via a resist layer in order to cut a portion to be cut.

When the jetting material is continuously projected onto the workpiece through the resist layer, the propellant that has passed through the opening of the resist layer may enter below the resist layer, causing peeling on the surface of the workpiece. When such peeling occurs, the reinforcing fibers of the work piece are exposed as fluff on the surface of the work piece. In the method according to the above side surface, the injection material is sprayed onto the workpiece through the resist layer having an opening having a diameter smaller than the desired diameter. In this method, the propellant that collides with the resist layer cuts the peripheral edge of the opening formed in the resist layer, so that the diameter of the opening gradually increases as the processing time elapses. In this way, when holes are formed in the work piece while gradually increasing the diameter of the opening of the resist layer, even if the work piece is peeled off, the peeled portion is removed as the work piece is processed. Will be done. As a result, it is possible to prevent peeling and fluffing from occurring on the surface of the work piece after processing.

In one embodiment, the ratio of the diameter of the opening to the desired diameter may be 0.84 or more and 0.94 or less. By setting the ratio of the diameter of the opening to the desired diameter in this way, it is possible to efficiently process while maintaining the accuracy of the diameter of the hole after processing.

In one embodiment, in the step of injecting the injection material onto the work piece, the injection material is injected from the nozzle toward the work piece, and the angle formed by the surface of the work piece and the injection direction of the injection material from the nozzle. May be 90 ° ± 5 °. By injecting the injection material onto the workpiece at such an angle, it is possible to suppress the occurrence of peeling on the surface layer of the resin, and as a result, it is possible to suppress fluffing.

In one embodiment, the nozzle may be configured to suck the propellant by introducing compressed air into the nozzle and inject it together with the compressed air as a solid air two-phase flow. Fiber reinforced plastics are difficult to cut with respect to blasting, and it takes a considerable amount of time to complete the machining. In this embodiment, since the injection material can be continuously injected from the nozzle, the processing efficiency can be improved.

In one embodiment, the workpiece may be composed of a fiber reinforced plastic in which the cut reinforcing fibers are dispersed in a resin. Since the reinforcing fibers are dispersed in this type of fiber reinforced plastic in a non-directional manner, the surface may be peeled off from the reinforcing fibers as a starting point in the conventional drilling method, and the fiber reinforced plastic may be damaged. On the other hand, according to the drilling method of one embodiment, it is possible to prevent peeling or fluffing from occurring on the surface of the work piece even for such a work piece.

In one embodiment, the workpiece may be composed of a fiber reinforced plastic in which woven reinforcing fibers are infiltrated with a resin. Since this type of fiber reinforced plastic is obtained by alternately laminating reinforced fibers woven in a cloth shape and resin, the fiber reinforced plastic may be damaged by peeling between layers in the conventional drilling method. .. According to the drilling method of one embodiment, it is possible to suppress the occurrence of peeling or fluffing on the surface of the work piece even for such a work piece.

Another aspect of the disclosure provides a resist layer used in the drilling process described above. This resist layer is a polymer containing unsaturated polyurethane or rubber to which abrasion resistance is imparted as a main component. By using such a polymer as the material of the resist layer, it is possible to prevent the resist layer from being excessively deformed during the drilling process of the workpiece, so that the dimensional accuracy of the holes formed in the workpiece can be improved. Can be enhanced.

In another aspect of the present disclosure, there is provided a fiber reinforced plastic in which holes are formed by the above-mentioned drilling method. This fiber reinforced plastic has a plate shape having a thickness of 1.0 mm or more and 2.0 mm or less, and an angle formed by a plane orthogonal to the central axis of the hole and a wall surface forming the hole is 80 ° or more and 90 ° or less. When the angle formed by the plane orthogonal to the central axis of the hole and the wall surface forming the hole is 80 ° or more and 90 ° or less, the uniformity of the diameter of the hole is improved in the thickness direction of the fiber reinforced plastic. Can be made to. The plate shape referred to here includes not only a flat plate shape but also a curved plate shape.

In another aspect of the present disclosure, a fiber-reinforced plastic workpiece having a front surface and a back surface is formed with a hole having an opening on the front surface and the back surface and a first opening on the front surface side having a first area. A drilling method is provided. This method is a step of arranging a resist layer having a higher blast resistance than the work piece on the work piece, and the resist layer has a shape corresponding to the shape of the first opening and has a shape corresponding to the shape of the first opening. A second opening having a second area smaller than the first area is formed, and the process and the peripheral portion of the opening of the resist layer are cut and exposed from the second opening of the workpiece. It includes a step of injecting a propellant onto a work piece via a resist layer to cut a portion.

When the jetting material is continuously projected onto the workpiece through the resist layer, the propellant that has passed through the second opening may enter below the resist layer, causing peeling on the surface of the workpiece. When such peeling occurs, the reinforcing fibers of the work piece are exposed as fluff on the surface of the work piece. In the method according to the above side surface, the injection material is sprayed onto the workpiece through the resist layer in which the second opening having the second area smaller than the first area is formed. In this method, the propellant that collides with the resist layer cuts the peripheral edge of the second opening, so that the area of the second opening gradually increases as the processing time elapses. In this way, when holes are formed in the work piece while gradually expanding the area of the second opening, even if peeling occurs in the work piece, the peeled portion is removed as the processing of the work piece progresses. Will be done. As a result, it is possible to prevent peeling and fluffing from occurring on the surface of the work piece after processing.

According to various aspects and embodiments of the present disclosure, holes can be formed in the fiber reinforced plastic while suppressing the occurrence of fluffing and peeling.

It is a front view which shows by breaking a part of the sandblasting machine used in one Embodiment. It is a flowchart which shows the drilling processing method of one Embodiment. It is a figure which shows typically the scanning locus of the work of one Embodiment. It is sectional drawing which shows the work to which the drilling processing method of one Embodiment was applied. It is sectional drawing which shows the work to which the conventional drilling processing method was applied.

Hereinafter, various embodiments will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals, and duplicate description of the same or corresponding parts will be omitted. Moreover, the dimensional ratio of each drawing does not always match the actual dimensional ratio. The left-right, up-down directions in the description refer to the directions in the drawing unless otherwise specified.

FIG. 1 is a front view showing a part of the sandblasting machine 01 according to the embodiment broken. The sandblasting machine 01 is a device that projects a jetting material onto a work W (workpiece) made of fiber reinforced plastic to form holes in the work W. As shown in FIG. 1, the sandblasting machine 01 includes a housing 10, a fixed quantity supply mechanism 20, a separation mechanism 30, a suction mechanism 40, a nozzle 50, and a control device 60.

The housing 10 has a processing chamber R defined inside the housing 10. A door 11 is provided on the front surface of the housing 10, and an operator can access the processing chamber R by opening the door 11. The processing chamber R is provided with a nozzle fixing jig 12, a processing table 13, and a moving mechanism 14.

The nozzle fixing jig 12 is a mechanism for holding the nozzle 50, and the nozzle 50 can be moved along the height direction. Therefore, the nozzle fixing jig 12 is configured so that the distance between the nozzle 50 and the work W can be freely adjusted.

The moving mechanism 14 is provided on a gantry 15 provided at the lower part of the housing 10, and is arranged below the nozzle 50. In one embodiment, the moving mechanism 14 may be a plate-like body having a large number of through holes formed therein. By forming such a through hole in the moving mechanism 14, the injection material injected from the nozzle 50 can be passed toward the bottom of the housing 10.

A processing table 13 is provided on the moving mechanism 14, and supports the work W placed on the processing table 13. The moving mechanism 14 is capable of horizontally transporting the processing table 13 and the work W supported on the processing table 13 by, for example, the driving force of the motor. For example, the moving mechanism 14 is an XY stage that extends the work W in the horizontal direction and moves the work W along the X and Y directions (see FIG. 3) that are orthogonal to each other.

A fixed quantity supply mechanism 20 is provided above the processing chamber R. The fixed quantity supply mechanism 20 includes a storage hopper 21 and a transport path 22, and supplies the injection material in the storage hopper 21 to the nozzle 50 in a fixed quantity via the transport path 22. The structure of the fixed quantity supply mechanism 20 is not limited as long as a constant amount of injection material can be supplied to the nozzle 50. For example, as the fixed quantity supply mechanism 20, a screw feeder, a vibration feeder, or a table feeder can be used. In the embodiment shown in FIG. 1, a screw feeder is used as the fixed quantity supply mechanism 20.

A separation mechanism 30 is provided above the storage hopper 21 of the fixed quantity supply mechanism 20. The separation mechanism 30 is connected to the storage hopper 21 of the fixed quantity supply mechanism 20. The separation mechanism 30 has a substantially inverted pyramid shape, collects used propellant, and classifies it into reusable propellant and dust. One end of the first transport pipe P1 is connected to the separation mechanism 30. The other end of the first transport pipe P1 is connected to the bottom of the housing 10. Therefore, the space in the processing chamber R and the space in the fixed quantity supply mechanism 20 are continuous via the first transport pipe P1. In the embodiment shown in FIG. 1, a cyclone type classifier is used as the separation mechanism 30, but any other classifier such as a wind power type classifier or a screen type classifier may be used as the separation mechanism 30. Can be done.

Further, one end of the second transport pipe P2 is connected to the separation mechanism 30. The other end of the second transport pipe P2 is connected to the suction mechanism 40. The suction mechanism 40 is a mechanism for making the processing chamber R a negative pressure so that the injection material does not leak to the outside of the processing chamber R and sucking the particles including the injected injection material. The suction mechanism 40 is a light particle classified by a separation mechanism 30 (cyclone type classifier) via a second transport pipe P2 (injection material having a size unsuitable for reuse, work W, and cutting powder of the sheet 70). ) Is collected. Further, the suction mechanism 40 has a function of creating a negative pressure in the internal space of the separation mechanism 30 and transferring the used injection material collected at the bottom of the housing 10 to the separation mechanism 30.

The nozzle 50 is a mechanism for injecting an injection material onto the work W, and has a nozzle holder 51, an air nozzle 52, and an injection nozzle 53. The nozzle holder 51 is connected to the fixed quantity supply mechanism 20 via the injection material hose H2. A compressor C is connected to the air nozzle 52 via an air hose H1. In one embodiment, a solenoid valve VL1 and a valve VL2 may be provided between the air nozzle 52 and the compressor C. When the compressor C is operated, compressed air is injected from the air nozzle 52, and the inside of the nozzle holder 51 becomes negative pressure. As a result, the injection material stored in the storage hopper 21 is sucked into the nozzle holder 51 via the transport path 22 and the injection material hose H2, and is mixed with the compressed air inside the injection material to form a solid air two-phase flow. It is injected from the injection port of 53 toward the work W. Since the nozzle 50 having such a configuration can continuously inject the injection material, the work W can be continuously processed for a long time.

A so-called direct pressure type nozzle may be used as another type of nozzle. The direct pressure type nozzle is superior in cutting ability to the nozzle 50 of the present embodiment, but it is difficult to continuously process for a long time.

The propellant injected from the nozzle includes metal or non-metal shots, grids, cut wires, ceramic particles (alumina, silicon carbide, zircon, etc.), natural stone particles (emery, silica stone, diamond, etc.). ), Plant-based particles (walnut shell, peach seed, apricot seed, etc.), resin-based particles (nylon, melamine, yulia, etc.) and the like are exemplified. Since fiber reinforced plastic is a material that is difficult to cut, if a relatively hard material is selected as the injection material, the work W can be cut efficiently.

The control device 60 is a computer including a processor, a storage unit, an input device, a display device, and the like, and controls each unit of the sandblasting machine 01. In one embodiment, the control device 60 sends a control signal to the moving mechanism 14, the fixed quantity supply mechanism 20, the suction mechanism 40, and the solenoid valve VL1, and the positions of the moving mechanism 14 in the X and Y directions and the fixed quantity supply mechanism 20. It controls the operation, the operation of the suction mechanism 40, the opening and closing of the solenoid valve VL1, and the like. As the control device, various arithmetic units such as a personal computer, a motion controller such as a programmable logic controller (PLC) and a digital signal processor (DSP), a high-performance mobile terminal, a high-performance mobile phone, and the like can be used.

Hereinafter, a drilling method using the sandblasting machine 01 of one embodiment will be described with reference to FIG. In this way, holes H having a desired diameter d ₁ to the fiber reinforced plastic of the work W is formed. This work W has a flat plate shape and has an upper surface (front surface) 82 and a lower surface (back surface) 84 facing each other (see FIG. 4). The hole H to be formed in the work W is a through hole extending from the upper surface 82 to the lower surface 84, and is open to the upper surface 82 and the lower surface 84. The top surface 82 side of the hole H opening (first opening) 86 has a desired diameter _{d 1.} In other words, the hole H to be formed on the workpiece W is a through hole having an opening 86 of the area corresponding to the desired diameter d ₁ to the upper surface 82 side (the first area). In the following, an example in which the work W is made of glass fiber reinforced plastic (GFRP), which is a kind of fiber reinforced plastic, will be described.

The desired diameter d ₁ of the opening 86 indicates the length of the widest portion of the diameter of the opening 86. For example, the longest among straight lines the ellipse major axis desired diameter d _1, and the opening 86 connecting any two corners of the polygon when a polygonal shape when the opening 86 forms an elliptical shape the length of the straight line becomes a desired diameter d _1. Hereinafter, an embodiment in which the opening 86 is circular will be described. In this embodiment, the diameter of the aperture 86 has a desired diameter d _1.

<S1: Preparation of resist layer>
In the drilling method according to the embodiment, step S1 is first performed. In step S1, a sheet 70 that functions as a resist layer is prepared. The sheet 70 is softer than the injection material and is made of a material capable of absorbing the impact force of the injection material. Therefore, the sheet 70 has higher blast resistance than the work W made of fiber reinforced plastic.

The sheet 70 is formed with one or more openings (second openings) 71 (see FIG. 4). The opening 71 has a shape corresponding to the shape of the opening 86 of the hole H. For example, the opening 71 has a planar shape such as a circle, an ellipse, or a polygon, depending on the shape of the opening 86. In one embodiment, the opening 71 of the sheet 70 has the same shape as the opening 86 of the work W. However, the diameter d _{2 of the} opening 71 is formed to be smaller than the desired diameter d ₁ . In other words, the opening 71 has an area (second area) smaller than the area of the opening 86. The ratio (d ₂ / d ₁ ) of the diameter d ₂ of the opening 71 to the desired diameter d ₁ is set within the range of 0.84 or more and 0.94 or less, particularly 0.90 or more and 0.94 or less. You may. As will be described later, if this ratio is too small, the chances of the work W colliding with the injection material are too small, and the drilling time becomes long. On the contrary, if this ratio is too large, the surface layer of the work W is likely to be peeled off. Here, the diameter d ₂ of the opening 71 indicates the largest diameter among the diameters defined by the opening 71. For example, any two corners of the polygon when the major axis diameter d ₂ next to the opening 71, the planar shape of the opening 71 forms a polygonal shape of the elliptical shape in the case where the planar shape of the opening 71 forms an elliptical shape The length of the longest straight line connecting the _two is the diameter d ₂ . Hereinafter, an embodiment in which the planar shape of the opening 71 is circular will be described. In this embodiment, the diameter of the opening 71 is the diameter d ₂ .

As the material of the sheet 70, for example, various rubbers, nylon, polyethylene (PE), polypropylene (PP), polyurethane, acrylic and other thermoplastic resins are used. For example, as the material of the sheet 70, wear-resistant rubber can be used. The wear resistance of rubber can be easily adjusted by changing the blending ratio of a filling reinforcing material such as calcium carbonate to natural rubber or synthetic rubber as a main raw material. Therefore, by using wear-resistant rubber as the material of the sheet 70, it is possible to easily obtain a resist material having wear resistance suitable for drilling. In one embodiment, a wear-resistant rubber in which a reinforcing filler is blended in a ratio of 60 wt% or more and 70 wt% or less in natural rubber or synthetic rubber may be used as the material of the sheet 70.

Further, since polyurethane is generally excellent in elasticity, thermal deformation temperature and impact strength, the accuracy of the diameter of the hole H formed in the work W can be improved by using polyurethane as the material of the sheet 70. Can be done. Further, it is possible to easily form an opening 71 having a small diameter (for example, φ2 mm or less) in the polyurethane sheet 70. As will be described later, in the method of one embodiment, the peripheral portion 72 of the opening 71 of the sheet 70 is cut by the injection material, and the portion of the work W exposed from the opening 71 is cut. At this time, if the peripheral edge portion 72 of the sheet 70 is cut more than necessary, fluffing or peeling may occur on the surface of the work W, or the dimensional accuracy may be lowered. Therefore, the material of the sheet 70 is selected in consideration of elasticity, thermal deformation temperature and impact resistance. For example, since unsaturated polyurethane is generally excellent in elasticity, thermal deformation temperature, and Charby impact strength, the sheet 70 may be composed of a polymer containing unsaturated polyurethane as a main component. The content of unsaturated polyurethane may be 50 wt% or more, or 50 wt% or more and 70 wt% or less.

In one embodiment, the sheet 70 may be formed from a photosensitive resin molded into a film. When forming the sheet 70 from the photosensitive resin, first, a transparent pattern mask on which the opening pattern is printed is placed on the sheet 70, and the sheet is passed through the pattern mask from an ultraviolet light emitting source provided above the sheet 70. The 70 is irradiated with ultraviolet rays. The region of the sheet 70 that does not overlap the print pattern is cured by this irradiation with ultraviolet rays, but the portion that overlaps the printed opening pattern becomes a shadow and is not cured. Next, the uncured region of the sheet 70 is removed by washing away the sheet 70 after irradiation with ultraviolet rays using a developing solution. From such a series of steps, a plurality of openings 71 can be formed in the sheet 70.

Further, in step S1, the prepared sheet 70 is arranged on the work W. In one embodiment, the sheet 70 may be sticky. In this case, after the sheet 70 is attached to the upper surface of the work W, the sheet 70 can be brought into close contact with the work W by reducing the pressure in the vacuum chamber. Further, by subsequently heating the work W at a temperature of 60 ° C. or higher and 90 ° C. or lower, the work W and the sheet 70 can be firmly adhered to each other.

<S2: Preparation of sandblasting machine>
Next, in the drilling method according to the embodiment, step S2 is performed. In this step S2, the sandblasting machine 01 is prepared. In step S2, the suction mechanism 40 is first activated to suck the processing chamber R. Next, the door 11 is unlocked, the door 11 is opened, and, for example, a predetermined amount of injection material is thrown into the processing chamber R by an operator. Next, the suction force of the suction mechanism 40 transfers the injection material to the storage hopper 21 of the fixed quantity supply mechanism 20 via the first transport pipe P1 and the separation mechanism 30. After that, the door 11 is closed and locked. Since the inside of the processing chamber R becomes a negative pressure due to the suction of the suction mechanism 40, outside air flows into the processing chamber R from a suction hole (not shown) provided so as to communicate with the outside.

In step S2, for example, the control device 60 of the sandblasting machine 01 is operated, the solenoid valve VL1 provided in the path for supplying compressed air to the nozzle 50 is set to “open”, and the fixed quantity supply mechanism 20 is set to “ON”. Will be done. With such a setting, the injection material is supplied to the nozzle 50 and is injected from the nozzle 50. When the injection material is injected from the nozzle 50, the opening degree of the valve VL2 that adjusts the supply pressure of the compressed air is adjusted, and the injection speed of the injection material is adjusted.

Next, the control device 60 of the sandblasting machine 01 is operated, the solenoid valve VL1 is set to "closed", and the fixed quantity supply mechanism 20 is set to "OFF". With such a setting, the injection of the injection material from the nozzle 50 is stopped. After that, the door 11 is opened, and the work W is placed and fixed on the processing table 13. Next, the distance and angle between the nozzle 50 and the work W are adjusted by operating the nozzle fixing jig 12. When these operations are completed, the door 11 is closed and locked. The work W placed on the processing table 13 may be a plate-like body having a thickness of 1.0 or more and 2.0 mm or less.

Next, in step S2, processing conditions such as the movement locus of the movement mechanism 14 (distances in the X and Y directions in FIG. 3), the movement speed, and the number of scans are input to the control device 60.

<S3: Drilling process>
Then, step S3 is performed. In step S3, as will be described later, in order to cut a portion of the work W exposed from the opening 71 while cutting the peripheral edge portion 72 of the opening 71 of the sheet 70, the injection material is directed toward the work W via the sheet 70. Is injected. Hereinafter, an example of step S3 will be described in detail.

In step S3, first, the control device 60 is operated, the solenoid valve VL1 is set to “open”, and the fixed quantity supply mechanism 20 is set to “ON”. As a result, the injection material is injected from the nozzle 50. Next, the moving mechanism 14 is set to "ON", and the moving mechanism 14 operates so that the work W moves in the horizontal direction. For example, as shown in FIG. 3, the moving mechanism 14 moves the work W in the + X direction by a predetermined distance, then shifts the position of the work W in the + Y direction at a predetermined pitch, and then moves the work W in the −X direction. By repeating the movement, the work W is scanned in a comb-teeth shape with respect to the injection region A of the injection material. By moving the work W along such a scanning locus T, the moving mechanism 14 causes the injection material to collide with the entire surface of the work W substantially uniformly. In one embodiment, holes H may be formed in the work W by performing such scanning a plurality of times. The injection port of the nozzle 50 may have a rectangular flat shape. Since the injection port of the nozzle 50 has a rectangular planar shape and its long sides are arranged so as to coincide with the Y direction, the injection materials collide when the work W is scanned in the X direction. The area can be increased, and as a result, the processing efficiency of the work W can be improved.

As described above, the moving mechanism 14 conveys the work W in the X and Y directions, so that the hole H is formed in the region of the work W that is not covered by the opening 71 of the sheet 70. Here, as shown in FIG. 4, the injection material is projected from the nozzle 50 toward the region including the opening 71 and the peripheral edge portion 72 of the opening 71. Therefore, in step S3, as shown in FIG. 4, the peripheral portion 72 of the opening 71 is cut while the region of the work W exposed from the opening 71 is cut. Since the sheet 70 has higher blast resistance than the fiber reinforced plastic constituting the work W, the peripheral edge portion 72 of the sheet 70 is cut more slowly than the work W. Therefore, in step S3, while the diameter (area) of the opening 71 of the sheet 70 is gradually expanded, the region of the work W exposed through the opening 71 is cut so that the cutting area of the work W does not become excessive. .. As a result, the work W is prevented from peeling off on the surface layer. In step S3, the projection of the injection material until the diameter of the hole H formed in the workpiece W has a desired diameter d ₁ is continued.

FIG. 5 shows the shape of the hole H formed in the work W when the diameter d ₂ of the opening 71 and the desired diameter d ₁ are set to be the same. That is, FIG. 5, without cutting the peripheral edge portion 72 of the seat 70 shows a conventional method of forming a direct desired diameter d ₁ of the holes H in workpiece W. In the case where the fiber reinforced plastic constituting the work W has a structure in which the cut reinforcing fibers are dispersed in the resin, when the propellant is projected onto the work W, the reinforcing fibers dispersed in the non-directional direction are the starting point of destruction. As a result, peeling occurs on the surface of the work W. Further, in the case where the reinforcing fibers woven with the fiber reinforced plastic constituting the work W are infiltrated into the resin, the cloth-like reinforcing fibers serve as the starting point of fracture and peeling occurs on the surface of the work W. To do. After these peeling occurs, further continuing the cutting diameter of the hole H formed in the workpiece W, and finally becomes greater than the desired diameter d _1, a surface portion not circular, the further holes H Fluffing of reinforcing fibers occurs on the wall surface (see the circled part in the figure).

When the injection flow of the injection material is captured microscopically, if the injection flow flows along the surface of the work W, the surface layer of the work W is likely to peel off due to the characteristics of the fiber reinforced plastic. When peeling occurs on the surface layer of the work W, the reinforcing fibers are exposed on the surface layer and fluffing occurs. On the other hand, when the jet flow flows in the direction along the wall surface of the opening of the sheet 70 (that is, the direction perpendicular to the X direction and the Y direction), peeling of the work W on the surface layer can be suppressed, and as a result, the reinforcing fibers Fluffing can be suppressed. In the case where the fiber reinforced plastic constituting the work W has a structure in which the woven reinforcing fibers are infiltrated into the resin, the propellant collides with the work W from the direction of cutting the reinforcing fibers of the work W, so that the work W is reinforced. The fluffing of fibers can be further suppressed. Further, when the injection flow is greatly inclined with respect to the surface of the work W, the collision energy of the injection material becomes insufficient, the holes H cannot be formed in the work W, and the reinforcing fibers can be cut. The reinforcing fibers may be exposed as fluff on the outer peripheral surface of the hole H. Therefore, in one embodiment, the nozzle 50 may be arranged so as to be 85 ° or more and 95 ° or less (that is, in the range of 90 ° ± 5 °) with respect to the surface of the work W. In other words, the nozzle 50 is arranged so that the angle formed by the surface of the work W and the injection direction of the injection material is 85 ° or more and 95 ° or less.

Processing so that the angle of the wall surface of the hole H formed in the work W is appropriate is advantageous in terms of performance. For example, when the hole H formed in the work W is for joining, the higher the verticality of the wall surface forming the hole H, the thicker the gap between the joining member such as a bolt and the wall surface of the hole H. It becomes even in the vertical direction, and as a result, rattling after joining can be suppressed. Further, when the hole H formed in the work W is intended to improve the sound absorption property, the higher the verticality of the wall surface forming the hole H, the more the sound reflection by the wall surface of the hole H can be prevented. As in these examples, the angle formed by the wall surface with respect to the plane orthogonal to the central axis AX of the hole H is preferably close to 90 ° in terms of performance, but the closer to 90 °, the lower the productivity. Therefore, from the viewpoint of productivity and performance, the angle of the wall surface defining the hole H with respect to the plane orthogonal to the central axis AX of the hole H may be 80 ° or more and 90 ° or less, and 80 or more and 85 ° or less. You may.

The particles containing the propellant projected onto the work W in step S3 are collected at the bottom of the housing 10 and transferred to the separation mechanism 30 via the first transport pipe P1 by the suction force of the suction mechanism 40. The particles transferred to the separation mechanism 30 are separated into reusable propellant and dust in the separation mechanism 30. The reusable propellant is stored in the storage hopper 21, and light dust is sucked by the suction mechanism 40 and collected by a collection filter provided inside the suction mechanism 40. The reusable injection material stored in the storage hopper 21 is transferred to the nozzle 50 in a constant amount and injected again toward the work W.

<S4: Recovery process>
After forming the hole H in the work W in the step S3, the step S4 is performed. In step S4, the control device 60 is operated, the moving mechanism 14 is set to “OFF”, the solenoid valve VL1 is set to “closed”, and the fixed quantity supply mechanism 20 is set to “OFF”. After that, the door 11 is unlocked, the door 11 is opened, and the work W is collected from the processing chamber R. Next, after the sheet 70 attached to the work W is peeled off, the propellant and dust adhering to the work W are removed by using an air blow, an ultrasonic cleaner, or the like, and a series of drilling operations is completed.

Next, an experimental example in which FRP drilling is performed using the drilling method of one embodiment will be described. In the experimental example, 100 substantially circular holes (10) having a diameter of φ2.0 mm (work surface side) were formed on a plate-shaped (200 mm × 200 mm × t1.0 mm) work W of glass fiber tempered glass (GFRP). (Piece x 10 pieces) was formed.

As the resist layer, a sheet (thickness 0.5 mm) containing unsaturated polyurethane or acrylic resin as a main component and having openings having a shape corresponding to the holes to be processed was used.
Resist A: Main component of unsaturated polyurethane (containing 53 wt%)
Resist B: Main component of unsaturated polyurethane (containing 73 wt%)
Resist C: Acrylic resin is the main component (containing 60 wt%)

Other main processing conditions are as shown in Table 1.

After drilling the work W, any 10 holes were selected from the 100 holes formed, and the work W was observed and evaluated using an electron microscope. The evaluation criteria are as follows.
<Progress of processing>
◯ ... All the holes penetrate, and the angle of the wall surface of all the holes is 80 ° or more and 90 ° or less.
Δ: All the holes penetrate, and the angle of the wall surface of all the holes is 60 ° or more and 80 ° or less.
X: There is a hole that does not penetrate, or there is a hole whose wall surface angle is 59 ° or less.
<Diameter of hole>
◯: All diameters on the work surface side are less than ± 7% of the target size (φ2.0 mm).
Δ: All diameters on the work surface side are ± 8% or more and 15% or less of the target dimension (φ2.0 mm).
X: There is a hole whose diameter on the work surface side is ± 16% or more of the target dimension (φ2.0 mm).
<Presence / absence of peeling>
◯ ・ ・ ・ All holes are circular.
Δ: There is a hole in the vicinity of the outer circumference where traces of surface layer peeling are observed, but it is less than 1 mm from the outer circumference of the circle.
X ... There is a hole in the vicinity of the outer circumference where traces of surface layer peeling can be observed, and the size is 1 mm or more from the outer circumference of the circle.
<Presence or absence of fluff>
○ ・ ・ ・ No fluffing can be confirmed in all holes.
Δ: There are holes where some fluffing is confirmed, but the exposed glass fiber is less than 0.1 mm.
X ... There are holes where fluffing is confirmed, and the exposed glass fiber is 0.1 mm or more.

Table 2 shows the processing conditions and evaluation results of various examples and comparative examples. In Table 2, "processing" represents the evaluation result regarding "progress of processing", "peeling" represents the evaluation result regarding "presence or absence of peeling", and "fluffing" represents the evaluation result regarding "presence or absence of fluffing". Represents. Further, the “nozzle angle” in Table 2 represents the angle of the injection flow of the injection material with respect to the surface of the work W, and 0 ° indicates that the injection flow faces the scanning direction side of the work W in the longitudinal direction at the start of scanning. It is the angle at which it is ejected horizontally. That is, the state in which the injection flow is flowing in the + X direction shown in FIG. 3 is set to 0 °.

(1) Effect of d ₂ / d _{1 In} Examples 1 to 6, all the evaluation items were evaluated as ○, and it was confirmed that the drilling process was performed well. Although the qualitative evaluations were the same, the diameters of the holes after processing tended to be closer to the target dimensions in Examples 2 and 3 than in Example 1.
In Comparative Example _{1 in} which d ₂ / d ₁ was smaller than 0.84, "progress of processing" was evaluated as x. It is presumed that this is because the injection material has too few opportunities to come into contact with the work W. In Comparative Example 2 in which d ₂ / d ₁ was larger than 0.94, the evaluations of "hole diameter", "presence or absence of surface layer peeling", and "presence or absence of fluffing" were all evaluated as Δ. ΔEvaluation was a deterioration in quality to the extent that there was no problem in practical use, but a deterioration in quality was observed as compared with Examples 1 to 5. Further, in Comparative Example 3 in which d ₂ / d ₁ exceeds 1 (that is, d ₂ > d ₁ ), the evaluations of “hole diameter”, “presence or absence of surface layer peeling”, and “presence or absence of fluffing” are evaluated as ×. It was. As d ₂ / d ₁ increases, the effect of suppressing the processed area by opening the resist layer decreases, so it is presumed that the surface layer of the work W has peeled off.

(2) Effect of nozzle angle All of Examples 1 to 6 were evaluated as ◯, and it was confirmed that the drilling process was performed well. In Comparative Example 4 and Comparative Example 5 in which the angle deviated from 90 ° ± 5 °, deterioration in quality was observed in the evaluation of “progress of processing” and “presence or absence of fluffing”. Regarding the "progress of machining", it is presumed that the quality deteriorated because the inclination angle of the jet flow with respect to the work W was large and the machining capacity was lowered. The Δ evaluation was a deterioration in quality to the extent that there was no problem in practical use, but in Comparative Example 5 in which the nozzle angle was larger, the evaluation was ×. Further, regarding "presence or absence of fluffing", it is presumed that fluffing occurred because the jet flow flowed along the surface of the work W.

(3) Effect of resist layer material In Example 1, Example 6 and Comparative Example 6, the processing conditions are the same except for the material of the resist layer. In Examples 1 and 6 in which the main component of the resist layer was unsaturated polyurethane, all the evaluation items were evaluated as ◯, and it was confirmed that the drilling process was performed well. Although the evaluation was the same in the qualitative evaluation, the diameter of the pores after processing was higher in Example 1 in which the content of unsaturated polyethylene was in the range of 50% or more and 70% or less as compared with Example 6. There was a tendency to be closer to the desired dimensions.

On the other hand, in Comparative Example 6 in which the main component of the resist layer was an acrylic resin, the evaluation items of the pore diameter, peeling, and fluffing were evaluated as Δ. ΔEvaluation was a deterioration in quality to the extent that there was no problem in practical use, but it was confirmed that the processing accuracy was lower than when a resist layer containing unsaturated polyurethane as a main component was used.

Although the embodiments have been described above, various modifications can be configured without being limited to the above-described embodiments. For example, in the drilling method according to the above embodiment, in step S1, the sheet 70 having an opening formed in advance is arranged on the work W, but in one embodiment, the sheet 70 having no opening 71 is formed. The opening 71 may be formed in the sheet 70 after the is arranged on the work W.

In the above embodiment, the drilling process for the work W made of glass fiber reinforced plastic (GFRP) has been described, but the drilling process method according to the above embodiment is carbon fiber reinforced plastic (CFRP) or aramid fiber reinforced plastic (Aramid fiber reinforced plastic). It can be applied to drilling of work W composed of all fiber reinforced plastics such as AFRP), Dyneema fiber reinforced plastic (DFRP), Zylon fiber reinforced plastic, and boron fiber reinforced plastic (BFRP).

01 ... Sandblasting machine, 10 ... Housing, 11 ... Door, 12 ... Nozzle fixing jig, 13 ... Processing table, 14 ... Moving mechanism, 15 ... Stand, 20 ... Fixed quantity supply mechanism, 30 ... Separation mechanism, 40 ... Suction mechanism , 50 ... Nozzle, 51 ... Nozzle holder, 52 ... Air nozzle, 53 ... Injection nozzle, 60 ... Control device, 70 ... Sheet, 71 ... Opening, 72 ... Peripheral part, A ... Injection area, H1 ... Air hose, H2 ... Injection material Hose, R ... processing room, T ... scanning locus, W ... work.

Claims (6)

A drilling method for forming holes having a desired diameter in a work piece made of fiber reinforced plastic.
A step of arranging a resist layer having an opening having a diameter smaller than the desired diameter on the workpiece.
A step of injecting a jet material onto the work piece via the resist layer in order to cut a portion of the work piece exposed from the opening while cutting the peripheral edge of the opening of the resist layer. only including,
A drilling method in which the ratio of the diameter of the opening to the desired diameter is 0.84 or more and 0.94 or less . In the step of injecting the injection material onto the work piece, the injection material is injected from the nozzle toward the work piece.
The drilling method according to claim 1, wherein the angle between the surface of the workpiece and the injection direction of the injection material from the nozzle is 90 ° ± 5 °. The drilling according to claim 2 , wherein the nozzle is configured to suck the injection material by introducing compressed air into the nozzle and inject it together with the compressed air as a solid air two-phase flow. Processing method. The drilling method according to any one of claims 1 to 3 , wherein the workpiece is composed of the fiber reinforced plastic in which the cut reinforcing fibers are dispersed in a resin. The drilling method according to any one of claims 1 to 3 , wherein the workpiece is composed of the fiber-reinforced plastic in which woven reinforcing fibers are infiltrated with resin. Before Symbol resist layer is a polymer comprising as a main component rubber unsaturated polyurethane or abrasion resistance is imparted, drilling method according to any one of claims 1 to 5.