JP2022045533A5 - - Google Patents

Description

The present invention is a curved surface development program that develops a curved surface into a plane using an arbitrary group of curves on the curved surface as a development reference line, and a tool path of the embroidery machine is calculated for the plane development drawing obtained using the curved surface development program. related to a toolpath calculation program .

Carbon fiber reinforced plastics (CFRP) have superior specific strength and specific modulus compared to steel, and their use is increasing, especially in the automotive and aerospace industries. For example, aircraft structures such as the Boeing 787 and Airbus A350XWB utilize as much as 50% composite materials on a weight basis. In recent years, much attention has been paid to Tailored Fiber Placement (TFP) technology invented by the Leibniz Institute (IPF Dresden) in Dresden, Germany. Using the TFP technique, it is possible to fabricate a preform for CFRP molding by embroidering carbon fiber tows along a predetermined trajectory on a base material such as a glass cloth material. A tow as used herein refers to a bundle of continuous untwisted carbon fiber filaments. A preform refers to a base sheet for CFRP molding embroidered with carbon fiber tows.
Sheet-shaped preforms are stacked along the designed female mold, and CFRP products are molded using vacuum assisted resin transfer molding (VaRTM). By using TFP technology to create a preform with carbon fiber tows arranged in the direction intended by the designer, it is possible to control the flow of fibers inside the molded product. As a result, compared with the conventional molding method using a cloth material, which is a fiber sheet in which carbon fibers are woven in the orthogonal direction, or a unidirectional fabric material, which is a fiber sheet in which carbon fibers are woven in only one direction, Since the degree of freedom in design is increased, there is a great advantage in terms of product functionality enhancement such as weight reduction and strength enhancement.

Here, in Patent Document 1, a target surface curvature line acquisition unit that obtains a plurality of maximum principal curvature lines and a plurality of minimum principal curvature lines on a formation target surface, and a formation target surface with a maximum principal curvature line and a minimum principal curvature line A shape acquisition device is disclosed that includes a planar area acquisition unit that obtains data indicating the shape of the corresponding planar area for each of the divided areas.
Further, in Patent Document 2, a first curvature line and a second curvature line, which are two curvature lines in either one of the maximum principal curvature direction and the minimum principal curvature direction, on a surface to be formed are obtained, and the maximum principal curvature A target surface curvature line for obtaining a plurality of third curvature lines that are curvature lines from the first curvature line to the second curvature line in a direction different from the first curvature line and the second curvature line among the direction and the minimum principal curvature direction an acquisition unit for developing the first curvature lines on a plane, isometriically developing each of the third curvature lines on the plane with a point included in the first curvature lines as a starting point, and developing the second curvature lines on the plane; Based on the deviation between the developed portion developed on the plane so as to pass through one of the end points of the third curvature line developed on the plane and the end points of the second curvature line developed on the plane and one or more third curvature lines, the plane A removal portion setting device is disclosed that includes a removal portion setting unit that obtains a portion to be removed from among.
In addition, in Patent Document 3, a thread made of high-strength fibers is sewn on a base material of a predetermined shape, and at least one surface of the base material is covered with a thread made of high-strength fibers. Threads made of high-strength fibers pierced with a needle on the base material are sewn in a mountain fold on at least one surface of the base material to form a continuous loop shape arranged in many rows, and a continuous loop shape is formed on the surface side. An FRP material is disclosed in which the mountain-folded tip of the loop-shaped thread is configured to be a free end.
Further, Patent Document 4 discloses a multilayer base material in which at least two sets of biaxially stitched base materials are laminated and integrated with an engaging material, wherein the biaxially stitched base material is composed of a large number of reinforcing fiber yarns. A plurality of sheets in which the threads are arranged in parallel are laminated so that the reinforcing fiber threads are oriented in two directions and sewn with a stitch thread, and the melting point Tmc of the engaging material is within the range of 80 to 200 ° C. and the melting point of the stitch yarn is in the range of (Tmc+10) to (Tmc+120)°C.
Further, Patent Document 5 discloses a laminated sheet including at least a portion in which layer A, layer B, and layer C are laminated in this order, wherein layer A is aligned in parallel in a certain direction and formed into a planar shape. The layer B is composed of a heat-fusible film, and the layer C is aligned in parallel in a direction different from the direction in which the filament A group is aligned to form a plane It is composed of a group of filaments C arranged in a shape, and the layers A, B and C are sewn and integrated with a plurality of sewing threads running in the longitudinal direction, and each sewing thread is knitted with a warp knitting structure. Laminated sheets for manufacturing FRP having a heat-fusible film as a matrix are disclosed.
In addition, in Non-Patent Document 1, by logically treating curved surfaces and skin development, geometric deformation (bending and drawing) can be quantified, and the work instruction line for steel processing can be given. A current map development technique is disclosed.
Also, in Non-Patent Document 2, four curves of each patch whose boundary lines are curvature lines while maintaining the correct length are mapped onto a plane, and they are connected as curves that are almost orthogonal to each other. A method for unfolding a curved surface is disclosed.

WO 2017/090749 JP 2016-91477 A JP 2010-280212 A JP 2007-160587 A Japanese Patent Application Laid-Open No. 2004-346175

Kohei Matsuo, et al., “Development of a new skin plate unfolding system that supports manufacturing of curved skin plates for ships”, Transactions of the Japan Society of Mechanical Engineers (C edition), November 2010, Vol. 76, No. 771, p. 51-56 M.Takezawa, 3 others, “Fabrication of freeform objects by principal strips”, 2016, ACM Transactions on Graphics (TOG), 35(6):225:1-225:12

TFP is a technique of embroidering carbon fiber tows on a base material in a two-dimensional plane, and when a complex three-dimensional design shape is targeted, a plan development view of the shape (cut shape of the preform) is required. In addition, the plane developed view needs to be a developed shape with high restoration accuracy in order to suppress the occurrence of wrinkles when laminating the designed shape to the female die.
In addition, since the shape of the non-developable surface cannot be developed on a flat surface without expansion and contraction, a cut line is required in the developed view, but it is desirable that the cut line is along the direction of the fiber to be oriented. This is because when embroidering (arranging) carbon fiber tows on a plan view using TFP technology, if there is no cut line along the flow to be arranged, the flow of the fibers to be arranged will be divided inside. (If you embroider across the score line, the carbon fiber tow will be cut there when you cut it.)
Furthermore, it is necessary to calculate a tool path along the flow suitable for the design purpose on the flat development view. As used herein, toolpath refers to the path along which the embroidery machine will embroider the carbon fiber tow. The requirements for this tool path are that the fiber tows to be laid out must have little variation in density, and the path must be such that the fibers are laid out along the flow desired by the designer in the final product.
From the above, in order to mold a CFRP product with a non-developable surface shape in which the internal fiber direction is controlled, it is necessary to calculate a plan development view with good restoration accuracy in which cuts are made along the direction in which the fibers are to be oriented. It is necessary to calculate a tool path that satisfies the above requirements on the flat development view.

Here, Patent Literature 1-2 and Non-Patent Literature 1-2 generate a plane development view using curvature lines, but isoparameter lines other than curvature lines, principal stretch lines, or principal stress lines It is not intended to generate a plan development view based on an arbitrary curve such as a line. Further, when generating the flat development view, the subsequent steps are not taken into consideration.
Moreover, Patent Documents 3 to 5 do not arrange tool paths based on a plan development view obtained by planar development of a curved surface.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a curved surface development program for generating a plane development drawing based on an arbitrary curve, and a tool path calculation program for arranging a tool path based on the plane development drawing.

A curved surface unfolding program corresponding to claim 1 is a curved surface unfolding program for unfolding a curved surface into a plane using an arbitrary group of curves on the curved surface as the unfolding reference line, the curved surface acquiring input curved surface data into a computer. A data acquisition step, a curve group calculation step of calculating an arbitrary group of curves intersecting the surface data in a net-like manner as a development reference line, and a surface patch acquisition step of acquiring a surface patch of an area surrounded by the arbitrary curve group. a geodesic curvature calculation step for calculating the geodesic curvature of an arbitrary curve group; a plane patch acquisition step for acquiring a plane patch by performing a calculation to expand the surface patch onto a plane using the geodesic curvature; A development plan generation step of arranging plane patches to generate a development plan and a development plan output step of outputting the development plan are executed.
According to the first aspect of the present invention, it is possible to obtain a plane developed view by arranging plane patches obtained by developing surface patches obtained with an arbitrary curve group on a curved surface as a reference.

According to a second aspect of the present invention, in the plane developed view generation step, a plurality of plane developed views are generated by changing the arrangement of the plane patches.
According to the second aspect of the present invention , it is possible to obtain a plurality of plan developed views with high restoration accuracy.

According to a third aspect of the present invention, in the plane development drawing generation step, a plurality of patterns of plane development drawings are generated by changing the arrangement of the plane patches.
According to the third aspect of the present invention, by changing the arrangement of the plane patches, plane developed views with different patterns can be generated, making it possible to develop a molded base material that increases the strength of the composite material product.

The present invention according to claim 4 is characterized in that the curves of the arbitrary curve group are any of isoparametric curves, principal stretch lines, or principal stress lines on the parametric curved surface.
According to the fourth aspect of the present invention, it is possible to generate a highly accurate plan developed view based on isoparameter curves other than curvature lines, principal stretch lines, or principal stress lines.

According to a fifth aspect of the present invention, the curved surface data is NURBS curved surface data.
According to the fifth aspect of the present invention, CAD, CAE, and CAM technologies, which share the same geometric representation as curved surface data, can be used in conjunction with each other.

A tool path calculation program corresponding to claim 6 is a program for calculating a tool path of an embroidery machine with respect to a plane development, wherein the computer obtains the plane development using a curved plane development program. a step to obtain a plan development view, a toolpath placement step to place the toolpath only inside the plan development view, a toolpath calculation step to calculate the toolpath inside the plan development view, and the calculated toolpath It is characterized by executing a tool path output step to output.
According to the sixth aspect of the present invention, the calculated tool path of the embroidery machine can be arranged on the plan view obtained by the curved surface development program. It is possible to calculate the tool path of the fiber tow that is arranged so that the unevenness of the fiber density is reduced while following the .

According to a seventh aspect of the present invention, in the tool path arrangement step, the types of boundary curves of the plan development are arranged and classified into development reference lines and boundary lines of the plan development.
According to the seventh aspect of the present invention, the tool path can be arranged in consideration of the development reference line and the boundary line.

According to the eighth aspect of the present invention, in the tool path placement step, the auxiliary line for reducing the deviation of the tool path is drawn inside the plan development drawing in consideration of the development reference line.
According to the eighth aspect of the present invention, it is possible to reduce the deviation of the tool path by using the auxiliary line at the time of arrangement, and to improve the accuracy of the tool path.

According to a ninth aspect of the present invention, in the tool path arrangement step, the boundary line of the flat development view is extended to avoid the influence of the boundary line to facilitate the arrangement of the tool path along the development reference line. do.
According to the ninth aspect of the present invention, in the later offset work, it is possible to avoid the influence of the boundary line and facilitate the planning of the offset path along the flow of the development reference line.

According to the tenth aspect of the present invention, in the toolpath calculation step, the toolpath is offset to the inner side of the plan development in consideration of the width of the object to be embroidered, and the offset paths are sequentially planned.
According to the tenth aspect of the present invention, it is possible to plan a tool path in consideration of the width of an embroidery object such as a fiber tow to be placed.

The present invention according to claim 11 is characterized in that, in the toolpath calculation step, the offset paths are sequentially planned in consideration of the auxiliary lines.
According to the eleventh aspect of the present invention, the auxiliary line can be utilized as a guideline for the boundary line of the offset route, and the offset route can be accurately planned.

According to the present invention, in the tool path calculation step, after the tool path is planned, an outside offset curve is drawn outside the plan development view considering the width of the object to be embroidered, and unnecessary curves are trimmed. characterized by
According to the twelfth aspect of the present invention, it is possible to prevent a tool path from being generated that includes an unnecessary path in consideration of the width of the object to be embroidered.

According to the thirteenth aspect of the present invention, in the tool path calculation step, a path crossing the island part is added as an additional path to the isolated island part of the offset path in the plan development view, and the offset path and the additional path are used to It is characterized by planning toolpaths.
According to the thirteenth aspect of the present invention, the additional path that traverses the island portion enables the whole to be written in one stroke.

The present invention according to claim 14 is characterized in that, in the toolpath calculation step, the toolpath is calculated so as to be unicursal.
According to the fourteenth aspect of the present invention, it is possible to prevent the fiber tow of the object to be embroidered from being split inside the strip, thereby improving the strength.

According to the fifteenth aspect of the present invention, unicursal writing includes an end point designation step of designating an end point of a tool path as a starting point, a moving step of moving to the opposite end point, and a step of determining whether an unconnected end point remains. and a connection step of connecting to the nearest endpoint from the current endpoint if unconnected endpoints remain.
According to the fifteenth aspect of the present invention, it is possible to accurately and quickly convert a tool path into a single stroke.

The present invention according to claim 16 is characterized in that the calculation of the tool path is performed based on the NURBS curve.
According to the sixteenth aspect of the present invention, CAD software can use standard NURBS curves to calculate the tool path, which facilitates linkage with subsequent manufacturing (CAM) .

According to the surface development program of the present invention, a plane development view can be obtained by arranging plane patches obtained by developing surface patches obtained based on an arbitrary curve group on a curved surface.

Further, in the plane development drawing generation step, when a plurality of plane development drawings are generated by changing the arrangement of plane patches , it is possible to obtain a plurality of plane development drawings with high restoration accuracy.

In addition, in the plan development drawing generation step, when a plurality of patterns of plan development drawings are generated by changing the arrangement of the plane patches, the plan development drawings with different patterns can be generated by changing the arrangement of the plane patches, and the composite material product It is possible to develop into a molding base material that increases the strength of

In addition, if the curve of an arbitrary curve group is either an isoparametric curve, a principal stretch line, or a principal stress line on a parametric surface, an isoparametric curve other than the curvature line, the principal stretch line, or the principal stress line A highly accurate plan development view can be generated based on the lines.

Further, when the curved surface data is NURBS curved surface data, it becomes easier to use CAD, CAE, and CAM technologies in cooperation with each other, which share the same geometric expression as the curved surface data.

According to the tool path calculation program of the present invention, the calculated tool path of the embroidery machine can be arranged on the plane development obtained by the curved surface development program, and the plane development can be, for example, in a desired direction. It is possible to calculate the tool path of the fiber tows arranged so as to reduce the unevenness of the density of the fibers while keeping them along.

In addition, in the tool path placement step, when sorting out the types of boundary curves of the plan development view and classifying them into the development reference line and the boundary line of the plan development view, the tool path is arranged considering the development reference line and the boundary line. can be placed.

Also, in the toolpath placement step, when drawing auxiliary lines to reduce toolpath misalignment inside the flat development drawing in consideration of the development base line, use the auxiliary lines when arranging the toolpath. Misalignment can be reduced and toolpath accuracy can be improved.

In addition, in the toolpath placement step, if you want to extend the boundary line of the flat development drawing to avoid the influence of the boundary line and make it easier to place the toolpath along the development reference line, in the later offset operation, the boundary Line effects can be avoided to facilitate planning of offset paths along the flow of the deployment reference line.

Also, in the toolpath calculation step, if the width of the object to be embroidered is taken into consideration when planning an offset path in which the toolpath is offset to the inside of the flattened view, Width-aware toolpaths can be planned.

Also, in the tool path calculation step, when the offset paths are sequentially planned in consideration of the auxiliary lines, the auxiliary lines can be utilized as guidelines for the boundary lines of the offset paths, and the offset paths can be accurately planned.

Also, in the toolpath calculation step, after planning the toolpath, draw an outside offset curve that is offset to the outside of the plan view considering the width of the embroidery object, and trim unnecessary curves. Considering the width of the object, it is possible to prevent the generation of toolpaths containing unnecessary paths.

In addition, in the tool path calculation step, when planning the tool path using the offset path and the additional path, adding a path that crosses the island part as an additional path to the isolated island part of the offset path in the plan development view allows the whole to be unicursal with additional paths across the islands.

In addition, in the toolpath calculation step, when the toolpath is calculated so as to be drawn in a single stroke, the fiber tow of the embroidery object can be prevented from being split inside the strip, and the strength can be improved.

In addition, unicursal writing includes an end point designation step that designates the end point of the tool path that will be the starting point, a movement step that moves to the opposite end point, and an unconnected determination step that determines whether unconnected end points remain. , and connecting to the nearest endpoint from the current endpoint if there are remaining unconnected endpoints, unicursal scribing of the toolpath can be performed accurately and quickly.

In addition, when the toolpath calculation is based on the NURBS curve, the toolpath can be calculated using the standard NURBS curve in CAD software, and it is easy to link with subsequent manufacturing (CAM). Become .

1 is a diagram showing the configuration of a curved surface manufacturing system using a composite material according to an embodiment of the present invention; FIG. Processing flow of the surface expansion program Diagram showing the same coordinate system Diagram showing expansion of isosurface patch Diagram showing deployment and reconstruction of the same apple model Diagram showing a knitted model using equivalent parameter curves Diagram showing an orthogonal network of curves on the bonnet surface of the same car Diagram showing the end of the calculation of the same curve Processing flow of the same tool path calculation program A diagram showing an example of classification of boundary curves in the same plane development view A diagram showing an example of expanding the area of the development view of the same plane Diagram showing an example of the same offset Diagram showing an example of the same trim A diagram showing an example of classifying the same island and adding a toolpath A diagram showing an example of unicursal toolpath conversion on the inner offset curve that forms the same island. Diagram showing an example of unicursal writing of the entire toolpath Image of embroidering the object along the tool path created in the same way A diagram showing the processing procedure when the same offset curve deviates from the actual curve Diagram showing measurement results when applying a tool path calculation program to the hood of the same car A diagram showing the process of manufacturing a curved surface using the same composite material Conceptual diagram showing the flow from generation of same-plane development to product manufacturing Schematic diagram of the same CFRP manufacturing method Diagram showing the VaRTM and L-RTM devices under production A diagram showing the unicursal toolpath of a TFP embroidery machine applied to produce a molding substrate for the bonnet model of the same car. Diagram showing a molded substrate manufactured by the same TFP embroidery machine A diagram showing a CFRP automobile hood manufactured by the same VaRTM equipment A diagram showing the development process of the marine propeller blade curved surface along the curve A diagram showing the tool path of the molding substrate for the propeller blade model for the same ship. Diagram showing a molded substrate manufactured with the same TFP embroidery machine Diagram showing a CFRP ship propeller blade manufactured by the same L-RTM equipment

A curved surface development program, a tool path calculation program, a curved surface manufacturing method using a composite material, and a curved surface manufacturing system using a composite material according to embodiments of the present invention will be described.

FIG. 1 is a diagram showing the configuration of a curved surface manufacturing system using a composite material.
A curved surface manufacturing system using composite materials includes a computer 10 that executes a curved surface development program and a tool path calculation program, a cutter 20 that cuts a base material based on a plan development view, and an embroidery object that is embroidered on the base material. an embroidery machine 30, a manufacturing computer 40 that controls at least the cutting machine 20 and the embroidery machine 30, a resin molding means 60 that injects resin into a molding die 50 to obtain a composite material curved surface, and a CAD system that designs the curved surface data. 70. By using this curved surface manufacturing system, it is possible to manufacture composite material products having curved surfaces based on highly accurate molded substrates.
The computer 10 can be provided separately from the manufacturing system, but by incorporating it into the manufacturing system, the computer 10 can generate a plane developed view by the curved surface development program and calculate the tool path by the tool path calculation program in the manufacturing system. 10 can be used.
CAD system 70 is also linked to computer 10 via communication network 80 . This makes it easier for the computer 10 to acquire the curved surface data created by the CAD system 70 and to coordinate the designing of the curved surface and the manufacturing of the curved surface using the composite material.

Computer 10 and manufacturing computer 40 are remotely located and linked to each other. As a result, the computer 10 can generate the plan development view and calculate the tool path, and the manufacturing computer 40 can link and perform curved surface manufacturing using composite materials at separate locations. It should be noted that it is also possible to perform the generation of the flat development view and the calculation of the tool path in separate computers 10 after linking them.
In FIG. 1, business establishments A, B, and C have a manufacturing computer (A), a manufacturing computer (B), and a manufacturing computer (C) as manufacturing computers 40, respectively.
For example, office A is an office that consistently performs cutting, embroidery, and resin molding, and the CAD system 70 is linked to one installed at another location. A manufacturing computer (A) 40 at the office A controls the cutting machine 20 and the embroidery machine 30 . Business office B is a business office that performs curved surface design, cutting, and embroidery at the same location, and resin molding is entrusted to another business office. The business office C is a business office that only performs embroidery, and the design of curved surfaces and the generation of flat development drawings by the CAD system 70, as well as the cutting and resin molding, are performed at another business office.
In this way, the business forms from design to manufacture of embroidered molding substrates and manufacture of resin molded products can be realized in arbitrary combinations. The manufacturing computer 40 can also be controlled by separate manufacturing computers 40 for the cutting machine 20 and for the embroidery machine 30 .
At this time, it is preferable that the computer 10 and the manufacturing computer 40 are linked via the communication network 80 regardless of the form of the manufacturing computer 40 . In this case, the communication network 80 enhances the connectivity between the computer 10 and the manufacturing computer 40, thereby speeding up and facilitating manufacturing.
CAD system 70 and computer 10 are also preferably linked via communications network 80 .
However, these linkages are not essential, and it is also possible to exchange design information, calculation results, etc. using part of the information storage medium.
The molding die 50 is manufactured based on the curved surface data designed by the CAD system 70, and based on the same curved surface data, the computer 10 performs the planar development of the curved surface and the calculation of the tool path, under the control of the manufacturing computer 40. The manufactured molding substrate is placed on the molding die 50 .

FIG. 2 is a processing flow of the curved surface development program.
The curved surface development program is a program that develops a curved surface into a plane using an arbitrary group of curves on the curved surface as a development reference line, and is installed in the computer 10 .
The curved surface development program that started processing receives input of curved surface data and acquires the input curved surface data (curved surface data acquisition step S1). A user such as a designer inputs curved surface data using an interface such as a keyboard or a touch panel. Further, the curved surface data may be received and acquired from an external CAD (computer-aided design) system or the like.
The curved surface data acquired in the curved surface data acquisition step S1 is Bezier curved surface data (the first "e" in Bezier is a double), B-spline curved surface data, or T-spline (T -spline) surface data, but preferably NURBS surface data. By using NURBS surface data, it becomes easier to coordinate and utilize CAD (computer-aided design), CAE (computer aided engineering), and CAM (computer aided manufacturing) technologies that share the same geometric representation as surface data. .

After the curved surface data acquisition step S1, an arbitrary curve group that intersects the curved surface data in a net-like manner (net-like) as a development reference line is calculated (curve group calculation step S2).
In the curve group calculation step S2, a curve group along the flow on which the user wants to arrange the fibers is calculated with respect to the design curved surface. The family of curves is computed either over the surface in 3D space or over the surface's two-dimensional parameter space.
The curves of any family of curves to be calculated can be curvature lines, but are preferably either isoparametric curves, principal stretch lines, or principal stress lines on parametric surfaces. It should be noted that it is also possible to develop a curve group arbitrarily drawn on a curved surface by the user. An arbitrary curve group on a curved surface may be directly drawn on the curved surface according to the purpose, or a curve group drawn in the parameter space of the curved surface may be mapped as a curve group on the curved surface.
Besides curvature lines, the use of arbitrary curves based on the principal directions of the tensor quantities is conceivable. For example, curves along any direction with any angle to the axis made by the principal direction, and principal stretch lines and principal stress lines based on the stress tensor/stretch tensor, which are physical quantities. . A curve for a purpose is basically calculated based on the tensor quantity defined on the curved surface. By calculating the eigenvector from the eigenvalue analysis of the tensor on the curved surface and tracing based on it, it is possible to draw a group of curves possessed by the tensor quantity.
In addition, even for tensor quantities defined in three-dimensional space such as stretch and stress, under the assumption that the wall is thin, one of the main directions is modeled so that it matches the normal direction of the surface, so that It becomes possible to define orthogonal families of curves. On the other hand, in the present invention, one principal direction does not necessarily have to coincide with the normal line, since orthogonality is not a necessary condition.
In addition, it is possible to generate a flattened view with an orientation angle with respect to the target direction to which reinforcement is desired, instead of the curve along the main direction.
Furthermore, when a group of curves drawn in the parameter space of a curved surface is mapped as a group of curves on the curved surface, they are generally not orthogonal, but a curve group that does not contain singular points like isoparameter lines can be generated. It is easy to generate a generalized principal patch that is all rectangular.
Accordingly, it is possible to generate a highly accurate planar developed view based on isoparameter curves other than curvature lines, principal stretch lines, or principal stresses. Also, as described above, the arbitrary curve group may be a curve group arbitrarily drawn on the curved surface by the user.

After the curve group calculation step S2, surface patches, which are areas surrounded by arbitrary curve groups, are acquired (surface patch acquisition step S3).
A region (generally a rectangle) surrounded by curvature lines is called a “principal patch”. The curved surface development program of the present invention generalizes the curve group that serves as the development reference line, not limited to the curvature line, and generates a plane development diagram with an arbitrary curve group such as a parameter curve, a principal stretch line, or a principal stress line. do. Therefore, a surface patch, which is an area surrounded by arbitrary curve groups, can be expressed as a "Generalized principal patch".
A surface patch can be obtained by drawing an arbitrary group of curves on the surface.

After the surface patch acquisition step S3, the geodesic curvature of an arbitrary curve group is calculated (geodesic curvature calculation step S4). The geodesic curvature of a curve can be determined using differential geometry. A method for calculating the geodesic curvature will be described below.

FIG. 3 shows the coordinate system, FIG. 3(a) showing the Freneselle frame and the Darboux frame, and FIG. 3(b) showing the contact Darboux vector.
It is known that a curve on a developable surface (developable surface) can be developed on a plane by using the geodesic curvature of the curve on the surface. For example, in Non-Patent Document 3 (Shyuichi Izumiya and Saki Otani, Flat approximations of surfaces along curves, Demonstratio Mathematica, 48(2):217-241, 2015.), , introducing a so-called osculating developable surface. The direction, called the osculating Darboux vector, in the Darboux frame at each point of the surface reference line is the generator of the developable surface.
When developing an arbitrary curve on a surface into a plane using the geodesic curvature of the curve on the surface, first define a 3D Cartesian reference coordinate system o-xyz. Consider a planar curve r(t)=(u(t),v(t)) in the parameter space of a parametric surface R(u,v). Also, c(t)=R(u(t), v(t)) is a parametric curve. As shown in FIG. 3(a), the vectors of the unit tangent t, normal n, and binormal b are orthogonal frames moving along a path c(t) called the Frenet-Serret frame. Define Here, the unit tangent line t, the normal line n, and the binormal line b are calculated as in the following formula (1).
“·” (upper dot) represents differentiation with respect to parameter t. The Frenet-Serre formula is given by the following equation (2).
Λ=|c| (dotted above), κ(t) and τ(t) are the parameters velocity, curvature and torsion of curve c(t), respectively.

As shown in FIG. 3(a), the Darboux frame (t, N, B) is a similar orthogonal frame, containing curved geometry and evaluated by equation (3) below.
The subscripts u, v used represent partial derivatives with respect to the indicated variables. The movement of the Darboux frame is given by equation (4) below.
κg(t), κn(t), and τg(t) are the geodesic curvature, normal curvature, and geodesic torsion, respectively.

Here, the unit contact Darboux vector is defined by the following equation (5).
This is shown in FIG. 3(b). From equation (4) and B·N=0 and t·N=0, τg and κn can be derived from equation (6) below.
Now assume that Λ≠0. Substituting equation (6) into the numerator of equation (5) yields the following equation (7).
"'" represents the derivative with respect to the arc length parameter s. The results show that the contact Darboux vector coincides with the linear vector direction of the developable surface defined as the tangential plane envelope along c(t).

Let c(t) be the reference line and let do(t) be the generator of the ruled surface D(t, μ) as in equation (8) below.
It is easy to show that t, d0, and d0 (with upper dots) are all on the tB plane, and the following equation (9) is obtained.
As a result, D(t, μ) is a developable curved surface, which is called an osculating developable surface. The curved surface normal of the contact developable surface is represented by the following formula (10).
δ(t) in equation (10) is expressed by the following equation (11).
Reducing No along D(t, 0)=c(t) results in the following equation (12).

Here we assume that κn(t)=0 occurs only at isolated points, where c(t) is locally planar and can be defined as No=n×t. Therefore, since the unit normal vector N(u,v) of the curved surface R(u,v) along c(t) coincides with the unit normal vector of D(t,0), The geodesic curvatures κg along c(t) are identical. Therefore, based on the curve (D(t, μ)) on the isometric surface, c(t) can be developed on the plane with the geodesic curvature as the curvature of the plane curve.
The geodesic curvature κg can be calculated as in the following equation (13).
E, F, and G in Equation (13) are the first elementary form metrics, and Christoffel symbols Γijk (i, j, k=1, 2) are defined as in Equation (14) below.
The first derivatives u (with upper dot), v (with upper dot), and the second derivatives u (with ¨) and v (with ¨) of the surface parameters can be obtained from predesigned curves, isoparametric curves, curvature It is obtained by differentiating a curve (u(t), v(t)) representing a preimage of a curve on a curved surface such as a line, principal stretch line, principal stress line.

Returning to FIG. 2, after the geodesic curvature calculation step S4, a calculation is performed to expand the surface patch onto a plane using the geodesic curvature, and a plane patch is acquired (plane patch acquisition step S5). Each curved surface patch is developed on a plane.

After the plane patch acquisition step S5, the acquired plane patches are arranged to generate a plane developed view of a shape in consideration of subsequent processes (plane developed view generation step S6).
Here, "considering the subsequent processes" means, for example, considering the embroidery process, which is one of the processes performed after the plan development drawing generation step S6, to prevent the work of the embroidery machine 30 from being hindered. It refers to generating multiple plane developed views by dividing into multiple strips of uniform size (collecting them together corresponds to the entire curved surface).
In the plane developed view generation step S6, it is preferable to generate a plurality of plane developed views by changing the arrangement of the plane patches. In this case, for example, a plurality of strips are generated by rearranging the planar patches in the direction of the maximum principal curvature line. By generating a plurality of plane developed views by changing the arrangement of plane patches, it is possible to obtain a plurality of plane developed views with high restoration accuracy for later processes.
In addition, in the plane developed view generation step S6, it is preferable to generate a plurality of patterns of plane developed views by changing the arrangement of the plane patches. In this case, for example, by rearranging the developed patches on the plane by rearranging them in the direction of the line of maximum principal curvature and the direction of the line of minimum principal curvature to create respective strips, two patterns of plane developed views are generated. can be done. By changing the arrangement of the plane patches and generating a plurality of patterns of plan development, it is possible to generate plan development with different patterns, and to develop a molding substrate that increases the strength of the composite material product.

Here, the development of surface patches (generalized principal patches) when the surface data acquired in the surface data acquisition step S1 is NURBS surface data will be described in detail.
A NURBS surface of order (p, q) is defined as in the following equation (15).

As described above, a principal patch is a patch whose constituent curves are curvature lines. In Non-Patent Document 2, the present inventors mapped the four curves of each principal patch onto a plane while maintaining the correct length, and connected them as curves that are nearly orthogonal to each other, thereby creating a free-form surface. Introduced an expansion method. The resulting quadrilateral planar patch is called the principal quad. The algorithm developed in [2] can also process patches bounded by N curvature lines to consider the singular points of the orthogonal network of principal curves, ie navel points.
According to the present invention, curvature lines can be generalized principal patches to arbitrary curve groups on a curved surface. It can be expressed as "curve A (generalized principal curves A)" and "curve B (generalized principal curves B)".

4A and 4B show the expansion of the surface patch, FIG. 4A shows the four curves of the surface patch, FIG. 4B shows the expansion of the four curves, and FIG. , which shows a quadrilateral planar patch obtained as .
A curve on the curved surface c(t) is developed into a plane by integrating equation (16) under the first equation of the Fresnet-Serre formula shown in equation (2).
Here κ is replaced by the geodesic curvature κg of c(t) based on the fact that the geodesic curvature along the curve c(t) is the same as the curvature of the unfolded curve.
As shown in FIG. 4, each surface patch is obtained by connecting four sides such that the correct length is maintained and the angle between each two adjacent sides is closest to the connection angle in the surface patch. to the plane.

Figure 5 shows the deployment and reconstruction of the apple model. Figure 5(a) shows the apple model represented by a NURBS surface (curved surface) in the upper figure, and the curve predesigned in the uv parameter space in the lower figure. 5(b) shows the development plane patch, FIG. 5(c) shows the main strip A (generalized A principal strip) in the upper figure, the main strip B (generalized B principal strip) in the lower figure, and FIG. d) shows the reconstructed model.
As shown in Fig. 5(a), ten 45° lines and ten A −45° line is drawn in the uv parameter space.
Each flat quadrangle in FIG. 5(b) is a planar patch (generalized principal quad). A distinguishing feature of this method is that the unfolding process can be reduced to a problem solved using a single-variable Newton's method for each patch. Patches consisting of three curves often occur near surface boundary curves, and the flattened three curves form a unique triangle, thus eliminating the need for optimization calculations. warn.

Once all the generalized principal patches are laid out on the plane, we connect each of the planar patches one by one by aligning adjacent edges that are of equal length using translation and rotation. If the connection is made along the B-side curve, the resulting strip is the main strip A and vice versa. FIG. 5(c) shows the main strip A and main strip B calculated from the pre-designed line shown in FIG. 5(a). These strips can be assembled into their original 3D shape in two ways. The pair of layers form a two-layer structure, one layer comprising the main strip A and the other layer comprising the main strip B. FIG. Each corresponding generalized planar patch is placed overlapping at the same location to reconstruct the 3D shape, one for main strip A and one for main strip B.

FIG. 6 shows a knitted model using isoparametric curves, FIG. 6(a) shows a curved surface model including isoparametric curves, FIG. 6(b) shows an unfolded planar patch, and FIG. c) shows main strip A (top) and main strip B (bottom) aligned unfolded planar patches, and FIG. 6(d) shows the knitted main strip.
The knitting model shown in FIG. 6 is developed along isoparametric curves as shown in FIGS. 6(a) to (c). The paper craft model shown in FIG. 6(d) shows a case where the main strip A and the main strip B are woven together to form a 3D curved surface model. Braided models cannot be used for TFP, but can be used for a variety of applications such as paper craft, sheet metal craft, and architectural design.

There are three well-known orthogonal networks of curves on free-form surfaces: curvature lines, principal stretch lines, and principal stress lines. A curve on a surface whose tangent to each point coincides with the principal direction of curvature at that point is called a line of curvature. Curvature lines indicate the maximum or minimum normal curvature direction flow across the curved surface. At non-umbilical points, there are two principal directions that are orthogonal, so the lines of curvature form an orthogonal network. The details of the method of drawing curvature lines by integrating the initial value problem of nonlinear simultaneous ordinary differential equations are described in Non-Patent Document 4 (T. Maekawa, F. E. Wolter, and N. M. Patrikalakis. Umbilics and lines of curvature for shape interrogation. Computer Aided Geometric Design, 13(2):133-161, 1996.). An umbilical point is a point on a curved surface with equal normal curvature in all directions, so the principal directions are indeterminate. Therefore, the orthogonal network of curvature lines is singular at the navel point, and therefore the surface patch, which is the area bounded by the curvature lines, is a patch bounded by N curvature lines instead of four. The expansion algorithm of Non-Patent Document 2 can handle such N patches. Calculation of the principal stretch lines and principal stress lines on the 3D freeform shell structure can be done in a similar way to the curvature lines.

In solid mechanics, a thin shell is expected to undergo large displacements and rotations because of its geometric dimensions, but has only small strains for bending-dominated deformations. Therefore, the Saint Venant-Kirchhoff constitutive model, which assumes a linear strain-stress relationship but accounts for nonlinear kinematics, is often used for shell geometry. It employs the classic Kirchhoff-Love shell theory. This assumes that the continuum of three-dimensional shells can be represented by the midplane and its normal vector field. So in theory, we need C1 continuity in the shell representation. The kinematics of the shell can be described by the first and second basic form factors of the midplane. Similar to the navel point, the point where the two principal stresses are equal is called the isotropic point. The state of stress at such a point is that of uniform radial compression or tension in all directions.

Since the geometric representation of the free-form surface is NURBS, we employ IGA (Isogeometric analysis) in which the NURBS surface is exactly transformed into NURBS elements without approximation to calculate the deformation of the thin shell structure. Furthermore, using the C1 continuous isogeometric discretization fits the Kirchhoff-Rabschell model. The knotspan of a NURBS surface subdivides the domain into elements, and the fields of interest (eg, displacement, velocity, temperature, etc.) are represented by the same basis functions as the NURBS surface.
Here, FIG. 7 is a diagram showing an orthogonal network of curves of the bonnet surface of an automobile, FIG. 7(a) showing the loads and boundary conditions of the IGA, FIG. (c) shows the principal stress lines.

8A and 8B are diagrams showing the end of the curve calculation, FIG. 8A showing the occurrence of narrow regions, and FIG. 8B showing the state where the curve calculation is finished because the distance between the curves is short. there is
A dense family of curvature lines, principal stretch lines, and principal stress lines tends to occur in high curvature, high deformation, and high stress regions, while a sparse family of curves is low curvature, low deformation, and low stress. displayed in the area. [2] introduces a graphical user interface (GUI) that allows the user to adjust the density of the orthogonal network of curves by applying functions that allow the user to 'add' and 'remove'. When the user selects one of the curves, a new curve is added by clicking on seed points on the surface where the curve is sparse and integrating in both directions. The "delete" function deletes an existing curve by clicking any point on the curve that the user wants to delete.

However, as shown in FIG. 8(a), the strip may be too narrow (too thin) to be manufactured.
In such a case, as shown in FIG. 8(b), when the curve is within a predetermined distance from other existing curves, the integral calculation for the curve is terminated.
The GUI is then used to interactively adjust the density of the curves, as shown in FIG. 8(c). Nevertheless, it is possible that the curve is inside the patch due to termination, as shown in FIG. 8(c). Such curves are deleted (trimmed) at patch boundaries, as shown in FIG. 8(d). Aligning adjacent edges of equal length using translation and rotation under the assumption that the curve starts and ends at the boundary of the input surface, as shown in FIGS. , it is straightforward to connect the planar patches one by one. However, in the case above, this assumption no longer holds. Therefore, as shown in FIG. 8(e), we divide the planar patches into groups according to the main curve passing through the surface from boundary to boundary. In FIG. 8(e), the upper diagram shows that the curved surface is divided into three regions according to the lines of minimum principal curvature, and the lower diagram shows that the curved surface is divided into seven regions according to the lines of maximum principal curvature. there is

Returning to FIG. 2, after the plan development drawing generation step S6, the plan development drawing is output (plan development drawing output step S7).
The output here includes output as image data and file data, as well as data transmission to other devices such as the manufacturing computer 40 that are linked with the computer 10 .

As described above, the surface development program provides the computer 10 with a surface data acquisition step S1 for acquiring input surface data, and a curve group for calculating an arbitrary curve group that intersects the surface data in a net-like manner as a development reference line. a calculation step S2; a surface patch acquisition step S3 for acquiring a surface patch of an area surrounded by an arbitrary curve group; a geodesic curvature calculation step S4 for calculating the geodesic curvature of an arbitrary curve group; Plane patch acquisition step S5 for acquiring a plane patch by performing calculations to develop the curved surface patch onto a plane using the surface patch, and plane development diagram generation for generating a plane development diagram of a shape in consideration of subsequent processes by arranging the acquired plane patches. A step S6 and a plane developed view output step S7 for outputting a plane developed view are executed. As a result, it is possible to arrange the plane patches obtained by developing the surface patches obtained based on an arbitrary curve group on the curved surface, and to obtain a plane development drawing in consideration of subsequent processes. In addition, since it is possible to calculate a plan development with good restoration accuracy in which cuts are made along the desired direction of the fiber orientation, it is possible to consider the fiber direction as a design parameter, which was conventionally considered difficult to control. , the degree of freedom in product design is improved. In addition, by controlling the fiber direction, it is possible to increase the strength, reduce the weight, add functionality, etc. of composite material products such as CFRP. In addition to carbon fiber, fibers such as aromatic polyamide resin fiber and ultra-high molecular weight polyethylene fiber can be used as the fiber depending on the use of the molded product.

FIG. 9 is a processing flow of the tool path calculation program.
The tool path calculation program is installed in the computer 10 to calculate the tool path of the embroidery machine 30 with respect to the plan view. The toolpath calculation program will be described with the example of a typical main strip, where the boundary curve consists of two development reference lines and two curved surface boundary curves.
The tool path calculation program that has started the process acquires a plan development view obtained using the curved surface development program (plan development view acquisition step S11).

After the plan development drawing acquisition step S11, the tool paths are arranged only inside the plan development plan (tool path arrangement step S12).
Here, FIG. 10 is a diagram showing an example of classification of boundary curves in a plan development view.
As shown in FIG. 10, each boundary curve for a part of a plan development drawing on which a tool path is drawn is defined as a development reference line 1 (e.g., isoparameter curve, principal stretch line, principal stress line, or curvature line) or a boundary of a curved surface. It is classified into two types, Line 2. In this way, in the tool path placement step S12, the types of boundary curves in the plan development are arranged and classified into development reference line 1 and boundary line 2 in the plan development, so that the development reference line 1 and the boundary line 2 The tool path can be placed in consideration of

Here, FIG. 11 is a diagram showing an example of area enlargement of the plan development view.
In the plan development view, the development reference line 1 of the boundary curve is extended to sufficiently widen the area of the plan development view. As a result, in the later-described offset operation, the influence of the boundary line 2 of the curved surface is avoided, and a tool path along the flow of the development reference line 1 is created. In FIG. 11, it extends straight from the end of the deployment reference line 1 in the tangential direction.
In this way, in the tool path arrangement step S12, the boundary line 2 of the plan development view is extended to avoid the influence of the boundary line 2 and facilitate the arrangement of the tool path along the development reference line 1. In the offset work, it is possible to avoid the influence of the boundary line 2 and to facilitate the planning of the offset path along the flow of the development reference line 1 .

Returning to FIG. 9, after the toolpath placement step S12, the toolpath inside the plan development view is calculated (toolpath calculation step S13).
Here, FIG. 12 is a diagram showing an example of offset.
In the toolpath calculation step S13, it is preferable to sequentially plan an offset path in which the toolpath is offset to the inside of the flattened view in consideration of the width of the object to be embroidered. This makes it possible to plan a toolpath that takes into account the width of an embroidery object such as a textile tow to be placed. The embroidery object is, for example, a carbon fiber bundle (tow).
FIG. 12 shows a state in which a plurality of inner offset curves 4 are drawn by offsetting inwards with respect to the boundary curve obtained by extending the development reference line and enlarging the area. Only the offset width between the boundary line 2 and the first inner offset curve 4 is 0.5 times the width of the object to be embroidered, and the subsequent inner offset curves 4 are offset by the same width as the width of the object to be embroidered.
Also, the toolpath calculations are based on NURBS curves. This allows CAD software to use standard NURBS curves to perform toolpath calculations, making it easier to work with later manufacturing (CAM).

FIG. 13 is a diagram showing an example of trimming.
In the toolpath calculation step S13, after the toolpath is planned, an outside offset curve 5 offset in consideration of the width of the object to be embroidered is drawn on the outside of the plan view, and unnecessary curves are trimmed. This prevents the generation of toolpaths that include unnecessary paths, taking into consideration the width of the object to be embroidered.
FIG. 13 shows a state in which an outer offset curve 5 is drawn outside the development reference line 1, and the boundary curve of the expansion area and the inner offset curve 4 outside the outer offset curve 5 are cut off as unnecessary curves. .

FIG. 14 is a diagram showing an example of island part classification and tool path addition.
After trimming the unnecessary curves, as shown in FIG. It is formed. The annular inner offset curve 4 without endpoints is a continuous closed contour and cannot be connected with other curves. The region formed by this annular inner offset curve 4 is classified as an island portion 6 which is an island-like region isolated from the inner offset curve 4 having an end point.
In the tool path calculation step S13, a path crossing the island part 6 is added as an additional path 7 to the isolated island part 6 of the offset path of the plan development view, and the tool path is calculated using the offset path and the additional path 7. To plan. By providing an additional path 7 which is a single smooth curve through all the inner offset curves 4 forming the island 6, the additional path 7 across the island 6 allows the whole to be unicursal. . As shown in FIG. 14, the length of the additional path 7 is aligned with the length of the inner offset curve 4 with endpoints. In this way, the additional path 7 is a path added to make the island portion 6 into a single stroke, and the added line is used as it is as a path when making a single stroke.

FIG. 15 is a diagram showing an example of unicursal conversion of the toolpath on the inner offset curve forming the island portion, and FIG. 16 is a diagram showing an example of unicursal conversion of the entire toolpath.
In the tool path calculation step S13, it is preferable to calculate so that the tool path can be drawn in one stroke. It should be noted that unicursal writing refers to connecting each independent curve so that it can be drawn with a single stroke (one stroke) to form a single curve that generates one tool path. By making the tool path in each strip unicursal, the fiber tow of the object to be embroidered can be prevented from breaking inside the strip, and strength can be improved.
In unicursal writing, first, as shown in FIG. 15, by merging the circular inner offset curve 4 forming the island portion 6 and the curve of the additional path 7, the offset of the island portion 6 is Write down the route. As a result, the outline of the island portion 6 can be drawn with a single stroke.
Next, as shown in FIG. 16, all the curves forming the toolpath are drawn in a single stroke by continuously connecting them with semicircles. Here, as shown in FIG. 9, end point specification step S13-1, movement step S13-2, disconnection determination step S13-3, and connection step S13-4 are executed.

In the end point designation step S13-1, the end point of the tool path to be the starting point is designated.
In the moving step S13-2, the end point, which is the starting point specified in the end point specifying step S13-1, is moved to the opposite end point.
In the unconnected determination step S13-3, it is determined whether an unconnected end point remains inside the strip based on the result of the movement step S13-2.
If it is determined in the unconnected determination step S13-3 that an unconnected end point remains inside the strip, the process proceeds to the connection step S13-4. In the connection step S13-4, a connection is made to an endpoint closest to the current endpoint, which has not yet been connected. After the connecting step S13-4, the process returns to the moving step S13-2.
On the other hand, if it is determined in the unconnected determination step S13-3 that unconnected end points remain inside the strip, the unicursal writing processing ends.
This allows accurate and rapid unicursal conversion of toolpaths. FIG. 17 is an image diagram of an embroidery object embroidered along the created tool path.

After completing the unicursal processing, an embroidery object such as a toe is placed along the unicursal tool path, and the gap area is checked.
18A and 18B are diagrams showing the processing procedure when the offset curve deviates from the actual curve, FIG. 18A shows the state where the auxiliary line is added, and FIG. Fig. 18(c) shows a state in which all the curves that make up the toolpath are continuously connected with semicircles to form a single stroke, and Fig. 18(d) shows a state in which all the curves forming the tool path are drawn in a single stroke. This shows a state in which an embroidery object such as a tow is placed along the drawn tool path and the gap area is checked.
If the distance between the two curves is large, the offset curve can deviate from the actual curve. In such a case, as shown in FIG. 18, an auxiliary line 3 is mapped to the center of the strip, the strip is divided into two strips, and the above toolpath placement step S12 and toolpath calculation step S13 are applied to each strip. Apply. In the toolpath placement step S12, the auxiliary line 3 that reduces the deviation of the toolpath is drawn inside the plan development drawing in consideration of the development reference line 1, so that the toolpath can be arranged using the auxiliary line 3 at the time of placement. It can reduce the deviation of the tool path and improve the accuracy of the tool path.
In the toolpath calculation step S13, the width of the object to be embroidered is taken into consideration, and the offset paths are sequentially planned by offsetting the toolpath to the inside of the flattened view. Width-aware toolpaths can be planned.
The auxiliary line 3 is, so to speak, a guideline of the boundary line of the offset curve (reference line for starting the offset) for improving the accuracy of the offset, and the line itself does not serve as a path.

Returning to FIG. 9, after the tool path calculation step S13, the calculated tool path is output (tool path output step S14). In this embodiment, the calculated toolpath is transmitted from computer 10 to manufacturing computer 40 via communications network 80 .
In this way, the toolpath calculation program can place the calculated toolpath of the embroidery machine 30 on the plan view obtained by the curved surface development program, and for example, in a desired direction with respect to the plan view. It is possible to calculate the tool path of the fiber tows arranged so as to reduce the unevenness of the density of the fibers while keeping them along.

Here, a measurement method for evaluating the algorithm of the tool path calculation program from the three viewpoints of orientation angle of fibers (embroidery object), overlap between fibers, and gaps between fibers will be described.
FIG. 19 is a diagram showing the measurement results when the tool path calculation program is applied to the developed view of the bonnet of the automobile, which is developed based on the curvature line. The angle of fiber orientation along the offset from the unfolded curves A and B was calculated at the point of intersection and evaluated for the difference from the perpendicular, FIG. and the ratio of dark pixels (with overlap) and light pixels (without overlap) on the image, and for the fiber gap area, colored pixels (with fibers) and white pixels (with fibers) inside the development view. none).
The first way to evaluate the results of the algorithm of the toolpath calculation program is the fiber orientation along the offset at the intersection of developed curve A and developed curve B, as shown in FIG. 19(a). It evaluates the deviation from the design angle for the angle between.
A second evaluation method evaluates the amount of overlap between embroidery objects (toes). A semi-transparent shading mode is used to place a 2D surface along the path with a width equal to the width of the toe, as shown in FIG. 19(b). Overlapping regions (overlapping regions) appear darker than non-overlapping regions and can be detected, so the ratio of dark pixels to bright pixels is evaluated.
A third evaluation method evaluates the amount of gap between embroidery objects (toes). As shown in FIG. 19(b), the ratio of interior white pixels to colored pixels is evaluated.

FIG. 20 is a diagram showing steps of a curved surface manufacturing method using a composite material.
In the method of manufacturing a curved surface using a composite material, first, a substrate obtained by cutting an original substrate with a cutting machine 20 based on a plane development obtained by using a curved surface development program, and an embroidery object to be embroidered on the substrate. is prepared (material preparation step S21). The base material is a glass cloth material or the like. Moreover, the cut base material includes a cut base material. By cutting only the base material, not the object to be embroidered, it is possible to prevent deterioration of the strength of the part.
If there are a plurality of planar developed views of a shape in consideration of subsequent steps, an identification code is given to the substrate (first identification code giving step S21-1). As a result, it is possible to prevent the base material from being mixed up, and to facilitate identification of the order in embroidering.

After the material preparation step S21, an embroidery object such as a carbon fiber tow is placed on the base material based on the tool path obtained using the tool path calculation program (material placement step S22). At this time, drawing a curve based on the tool path on the base material makes it easier to place the embroidery object.
Preferably, the embroidery object is a carbon fiber tow. This makes it possible to produce CFRP products that are superior in specific strength and specific modulus compared to steel.

After the material arrangement step S22, the embroidery object is embroidered on the base material according to the tool path by the embroidery machine 30 to obtain a molded base material (embroidery step S23). Molded base material (preform) can be cut based on a flat development drawing with good restoration accuracy, and embroidery objects such as fiber tow can be placed on the base material and embroidered based on the calculated tool path. Therefore, a highly accurate molded base material can be manufactured with less labor.

After the embroidering step S23, if there are a plurality of plane developed views of the shape in consideration of the subsequent steps, an identification code is given to the forming base material (second identification code giving step S24). As a result, it is possible to prevent the molding substrate from being mixed up, and to facilitate identification of the order in which the substrates are placed on the molding die 50 .

After the second identification code assigning step S24, when there are a plurality of plan developed views of a shape in consideration of subsequent steps, the plurality of forming substrates are connected (connecting step S25). By connecting a plurality of molding substrates to form a single piece, it is possible to reduce the labor involved in placing the molding substrate on the mold 50 .

Further, a molding die preparation step S26 for preparing a curved molding die 50, a molding substrate placement step S27 for placing the molding substrate obtained in the embroidery step S23 on the molding die 50, and a molding substrate placement step S27. It has a resin molding step S28 of injecting resin into the molded mold 50 for molding, and a curved surface completion step S29 of curing the resin to obtain a curved surface composed of the composite material integrated with the molding substrate. As a result, it is possible to manufacture a resin-molded curved surface using a composite material such as a CFRP product having a curved surface along a group of curves in which the arrangement of fiber tows or the like is calculated. As the resin, thermosetting resin such as epoxy and phenol, and thermoplastic resin such as polyolefin and polyamide can be used depending on the application of the molded product.
In addition, general molding methods such as the vacuum impregnation method (VaRTM) can be applied to the molding of CFRP.
Further, when the curved surface data acquired in the curved surface data acquisition step S1 is NURBS curved surface data and the tool path is calculated based on the NURBS curved surface, the curved molding die 50 is based on the NURBS curved surface, and the cutting machine The cutting of the substrate by 20 and the embroidery according to the toolpath by the embroidery machine 30 are based on NURBS curves. This allows CAD, CAE, and CAM techniques, which share the same geometric representation, to work together to manufacture surfaces made of composite materials using NURBS surfaces and NURBS curves. If the curved surface data acquired in the curved surface data acquisition step S1 is Bezier curved surface data, B-spline curved surface data, or T-spline curved surface data, and the tool path is calculated based on each curve, the curved surface molding die 50 is based on each curved surface, and the cutting of the substrate by the cutter 20 and the embroidery according to the tool path by the embroidery machine 30 are based on each curve.

In the forming base material placing step S27, it is preferable to stack and place a plurality of forming base materials. Thereby, the strength of the product using the composite material can be increased.
Moreover, it is preferable that the plurality of molding substrates are a combination of a plurality of patterns of molding substrates. Thereby, the strength of the product using the composite material can be further increased.
Moreover, it is preferable that the plurality of patterns of the molding substrate be a combination of patterns in which the carbon fibers of the carbon fiber tow are orthogonal. This makes it possible to obtain a CFRP product with increased strength. It is also possible to partially adjust the strength by locally changing the orientation of the carbon fibers.

FIG. 21 is a conceptual diagram showing the flow from generation of a flat development view to product manufacturing.
As described above, first, as shown in FIG. 21(a), the structured quadrilateral surface patches of the input surface are tessellated in the two-dimensional parameter space or the three-dimensional space of the input surface.
Next, as shown in FIG. 21(b), these surface patches are expanded to obtain plane patches.
Next, as shown in FIG. 21(c), the flattened planar patches are rearranged and aligned in two ways to generate a flattened view.
Next, as shown in FIG. 21(d), a tool path is generated.
Next, as shown in FIG. 21(e), an embroidery machine 30 is used to place an embroidery object on the developed patch to produce a molded base material (preform).
Finally, as shown in FIG. 21(f), a product such as a CFRP product having a curved surface made of composite material is formed.

Next, as manufacturing examples to which the present invention is applied, an automobile hood model and a marine propeller blade model will be described.
FIG. 22 is a schematic diagram of the CFRP manufacturing method, FIG. 22(a) showing VaRTM and FIG. 22(b) showing L-RTM. FIG. 23 is a diagram showing VaRTM equipment and L-RTM equipment during manufacturing, FIGS. ) shows the molding process of a marine propeller by the L-RTM equipment.
Using Tajima TCWM-101 (manufactured by Tajima Kogyo Co., Ltd.) as the embroidery machine 30, a carbon fiber tow was placed on the base material to produce a molded base material (preform). Toho Tenax HTS40 F22 12K 800TEXS (manufactured by Teijin Limited) was used as the carbon fiber tow, and MARINETEX 0.2A (manufactured by NICHIAS Corporation) with a thickness of 0.18 mm was used as the glass cloth substrate.
VaRTM and L-RTM equipment were used to fabricate CRFP shell structures. VaRTM processing is a low-cost composite manufacturing technology. As shown in FIG. 22(a), the dried molded substrate is placed over the open mold and covered with a vacuum film to inject the resin into the molded substrate under vacuum pressure and cured in an oven. On the other hand, L-RTM is a manufacturing process of composite materials using a closed mold. Both sides of the parts produced by the L-RTM machine are mirror-finished, whereas the parts produced by the VaRTM machine are mirror-finished only on the mold side.

FIG. 24 shows the unicursal toolpath of a TFP embroidery machine applied to produce a molded substrate for an automobile bonnet model, where symbol S indicates the starting point position and symbol E indicates the position of the starting point. Indicates the position of the end point of the unicursal toolpath. 24(a) is the path along the line of maximum principal curvature, and FIG. 24(b) is the path along the line of minimum principal curvature. 24(c) and (d) are enlarged views of the areas surrounded by squares in FIGS. 24(a) and (b), respectively.
A unicursal tool path (stroke path) is applied to produce the molded substrate of the car bonnet model shown in FIG. The paths along the lines of maximum and minimum principal curvature are shown in FIGS. 24(a) and (b), respectively. In addition, only the base material is cut, and the fiber directions in FIGS.

FIG. 25 is a diagram showing a shaped substrate produced by a TFP embroidery machine, and FIGS. 25(a) and (b) are respectively shaped substrates produced by a TFP embroidery machine based on the corresponding paths shown in FIG. 25(c) and (d) are enlarged views of carbon fiber tows corresponding to FIGS. 25(a) and (b), respectively. In addition, FIG. 26 is a diagram showing a CFRP automobile bonnet manufactured by the VaRTM equipment, FIG. 26(a) is a diagram showing the mirror-finished mold side, and FIG. be.
The molded substrates shown in FIG. 25 are stacked in a mold and a VaRTM machine is used to manufacture a CFRP automobile bonnet model.

FIG. 27 is a diagram showing the development process of the marine propeller blade curved surface along the curve, FIG. 27(a) shows the marine propeller blade, FIG. 27(b) shows the curvature line on the suction side of the blade, Figure 27(c) shows the curvature lines on the pressure side of the blade, Figure 27(d) shows a pre-image of the curvature lines, and Figure 27(e) shows the developed strips.
In addition, FIG. 28 is a diagram showing the tool path of the forming substrate of the marine propeller blade model, FIG. 28(a) shows the path along the line of maximum principal curvature, and FIG. shows the route along the Propeller blades are composed of multiple strips, and numbers (1-1 to 1-15) in FIG. 28(a) and numbers (2-1 to 2-8) in FIG. 28(b) are It is an identification code. 28(c) and (d) are enlarged views of the areas surrounded by squares in FIGS. 28(a) and (b), respectively.
The unicursal toolpath is applied to produce a molded substrate of a marine propeller blade model as shown in FIG. In addition, only the base material is cut, and the fiber directions in FIGS.

Figure 29 shows a shaped substrate produced with a TFP embroidery machine. FIG. 30 shows a CFRP marine propeller blade manufactured by the L-RTM equipment, where FIG. 30(a) shows the mirror-finished suction side and FIG. 30(b) shows the mirror-finished pressure side. is.
As shown in FIG. 29, molded substrates are produced on a TFP embroidery machine corresponding to paths with the same identification numbers as in FIG.

Finally, the following remarks are further disclosed with respect to the above description.

[Appendix 1]
A method for manufacturing a curved surface using a composite material, comprising:
A base material cut by a cutting machine based on a plane developed view obtained by using the curved surface development program according to any one of claims 1 to 5, and an embroidery object to be embroidered on the base material. A material preparation step to be prepared;
a material placement step of placing the embroidery object on the base material based on the tool path obtained using the tool path calculation program according to any one of claims 6 to 16;
an embroidering step of embroidering the object to be embroidered on the base material according to the tool path by means of an embroidery machine to obtain a shaped base material;
A method for manufacturing a curved surface using a composite material, characterized by comprising:
According to this configuration, the molding base material is cut based on a plan development view with good restoration accuracy, and an embroidery object such as a fiber tow is arranged and embroidered on the base material based on the calculated tool path. Therefore, a highly accurate molded base material can be manufactured with less labor.

[Appendix 2]
A supplementary note characterized by further comprising an identification code assigning step of assigning an identification code to each of the base material and/or the molding base material when there are a plurality of the plane development views of the shape in consideration of the subsequent process. 2. A method for manufacturing a curved surface using the composite material according to 1.
According to this configuration, it is possible to prevent the base material and the forming base material from being mixed up, and to facilitate identification of the order of embroidering or placing on the mold.

[Appendix 3]
The composite material according to Supplementary Note 1 or Supplementary Note 2, further comprising a connecting step of connecting a plurality of the molding substrates when there are a plurality of the plane development views of the shape in consideration of the subsequent steps. method of manufacturing the curved surface used.
According to this configuration, by connecting a plurality of molding substrates to form a single piece, it is possible to reduce the labor involved in placing the molding substrate on the mold.

[Appendix 4]
A forming mold preparing step of preparing the forming mold having the curved surface; a forming base placing step of placing the forming base obtained in the embroidery step on the forming mold; The method further comprises a resin molding step of injecting a resin into a mold for molding, and a curved surface completing step of curing the resin to obtain the curved surface made of the composite material integrated with the molding substrate. A method for manufacturing a curved surface using the composite material according to any one of appendices 1 to 3.
According to this configuration, it is possible to manufacture a resin-molded curved surface using a composite material such as a CFRP product, which has a curved surface along a curve group in which the arrangement of fiber tows or the like is calculated.

[Appendix 5]
5. The method for manufacturing a curved surface using a composite material according to appendix 4, wherein in the forming base material placing step, a plurality of the forming base materials are stacked and placed.
According to this configuration, the strength of the product using the composite material can be increased.

[Appendix 6]
6. The method for manufacturing a curved surface using a composite material according to appendix 5, wherein the plurality of molding substrates are a combination of a plurality of patterns of the molding substrates.
According to this configuration, it is possible to further increase the strength of the product using the composite material.

[Appendix 7]
7. The method of manufacturing a curved surface using a composite material according to any one of appendices 1 to 6, wherein the embroidery object is a carbon fiber tow.
According to this configuration, it is possible to manufacture a CFRP product that is superior in specific strength and specific modulus to steel.

[Appendix 8]
The method for manufacturing a curved surface using a composite material according to Appendix 7, which is a reference to Appendix 6, wherein the plurality of patterns of the molding substrate is a combination of patterns in which the carbon fibers of the carbon fiber tow are orthogonal. .
According to this configuration, a CFRP product with increased strength can be obtained.

[Appendix 9]
The mold for the curved surface is based on the NURBS curved surface, and the cutting of the base material by the cutter and the embroidery according to the tool path by the embroidery machine are based on the NURBS curve. A method for manufacturing a curved surface using the composite material according to any one of appendices 1 to 8.
According to this configuration, CAD, CAE, and CAM techniques, which share the same geometric representation, can be linked to manufacture curved surfaces made of composite materials using NURBS curved surfaces and NURBS curves.

[Appendix 10]
A curved surface manufacturing system using a composite material,
a cutting machine that cuts the base material based on the plan view;
an embroidery machine for embroidering an object to be embroidered on the base material;
a manufacturing computer that controls at least the cutting machine and the embroidery machine;
and a resin molding means for injecting resin into the molding die,
A system for manufacturing a curved surface using a composite material, characterized by carrying out the method for manufacturing a curved surface using a composite material according to any one of appendices 1 to 9.
According to this configuration, it is possible to manufacture a composite material product having a curved surface based on a highly accurate molding substrate.

[Appendix 11]
Further comprising a computer that executes the curved surface development program according to any one of claims 1 to 5 and the tool path calculation program according to any one of claims 6 to 16. A curved surface manufacturing system using the composite material according to appendix 10.
According to this configuration, it is possible to use a computer in a manufacturing system to generate a plane developed view by a curved surface development program and to calculate a tool path by a tool path calculation program.

[Appendix 12]
12. The system for manufacturing a curved surface using a composite material according to claim 11, wherein the computer and the manufacturing computer are remotely located and linked.
According to this configuration, the generation of the flat development view and the calculation of the tool path by the computer, and the manufacturing of the curved surface using the composite material by the manufacturing computer can be linked and performed at separate locations.

[Appendix 13]
13. A curved surface manufacturing system using a composite material according to appendix 12, wherein the computer and the manufacturing computer are linked via a communication network.
According to this configuration, it is possible to improve the linkage between the computer and the manufacturing computer by means of the communication network, thereby speeding up and facilitating manufacturing.

[Appendix 14]
14. A curved surface manufacturing system using a composite material according to any one of appendices 11 to 13, characterized in that the computer and a CAD system for designing the curved surface data are further linked.
According to this configuration, curved surface data created by a CAD system is acquired, and it becomes easier to coordinate from the design of the curved surface to the manufacturing of the curved surface using the composite material.

The present invention can be applied to general composite material products such as CFRP products in addition to the above-described automobile hoods and ship propellers.

1 development reference line 2 boundary line 3 auxiliary line 4 inner offset curve 5 outer offset curve 6 island portion 7 additional path 10 computer 20 cutting machine 30 embroidery machine 40 manufacturing computer 50 molding die 60 resin molding means 70 CAD system 80 communication network S1 Curved surface data acquisition step S2 Curve group calculation step S3 Curved surface patch acquisition step S4 Geodesic curvature calculation step S5 Plane patch acquisition step S6 Plane development view generation step S7 Plane development view output step S11 Plane development view acquisition step S12 Tool path arrangement step S13 Tools Path calculation step S13-1 End point designation step S13-2 Movement step S13-3 Disconnection determination step S13-4 Connection step S14 Tool path output step S21 Material preparation steps S21, S24 Identification code addition step S22 Material placement step S23 Embroidery step S25 Connection step S26 Forming mold preparation step S27 Forming substrate placement step S28 Resin molding step S29 Curved surface completion step

Claims (16)

A curved surface unfolding program for unfolding a curved surface onto a plane using an arbitrary curve group on the curved surface as an unfolding reference line,
to the computer,
a curved surface data acquisition step for acquiring input curved surface data;
a curve group calculation step of calculating an arbitrary curve group that intersects the surface data in a net-like manner as the development reference line;
a surface patch acquiring step of acquiring a surface patch of an area surrounded by the arbitrary curve group;
a geodesic curvature calculation step of calculating the geodesic curvature of the arbitrary curve group;
a plane patch obtaining step of obtaining a plane patch by performing a calculation to develop the surface patch into a plane using the geodesic curvature;
a plan development drawing generation step of arranging the acquired plane patches to generate a plan development plan;
and a plan development view output step of outputting the plan development view. 2. The curved surface development program according to claim 1, wherein, in said plane development drawing generation step, a plurality of said plane development drawings are generated by changing the arrangement of said plane patches. 3. The curved surface development program according to claim 1, wherein, in said plane development drawing generation step, a plurality of patterns of said plane development drawings are generated by changing the arrangement of said plane patches. 4. The curve according to any one of claims 1 to 3, wherein the curves of the arbitrary curve group are either isoparametric curves, principal stretch lines, or principal stress lines on a parametric surface. surface unfolding program. 5. The surface unfolding program according to claim 1, wherein said surface data is NURBS surface data. 1. A program for calculating an embroidery machine toolpath for a plan view, comprising:
to the computer,
A plane development view acquisition step of acquiring the plane development view obtained by using the curved surface development program according to any one of claims 1 to 5;
a toolpath placement step of placing the toolpath only inside the plan development view;
a tool path calculation step of calculating the tool path inside the plan development;
and a toolpath output step of outputting the calculated toolpath. 7. The toolpath calculation program according to claim 6, wherein, in said toolpath arrangement step, the types of boundary curves of said plan development are organized and classified into development reference lines and boundary lines of said plan development. . 8. The tool path calculation program according to claim 7, wherein in said tool path placement step, an auxiliary line for reducing deviation of said tool path is drawn inside said plane development drawing in consideration of said development reference line. . 3. The tool path placement step includes extending the boundary line of the plan development view to avoid the influence of the boundary line to facilitate placement of the tool path along the development reference line. The tool path calculation program according to claim 7 or claim 8. 10. The method according to any one of claims 6 to 9, wherein in the tool path calculation step, offset paths are sequentially planned by offsetting the tool paths to the inner side of the plan development in consideration of the width of the object to be embroidered. The tool path calculation program according to any one of items 1 and 2. Claim 10 quoting claim 8, or claim 10 quoting claim 8 and claim 9, characterized in that, in the tool path calculation step, the offset path is planned in order in consideration of the auxiliary line. The toolpath calculator program described in . In the toolpath calculation step, after planning the toolpath, an outer offset curve is drawn on the outside of the flat unfolded view considering the width of the object to be embroidered, and unnecessary curves are trimmed. 12. The tool path calculation program according to claim 9, or claim 10 or claim 11 quoting claim 9. In the tool path calculation step, a path crossing the island portion is added as an additional path to an isolated island portion of the offset path in the plan development view, and the tool path is calculated using the offset path and the additional path. 10. The tool path calculation program according to claim 10, or claim 11 or claim 12 quoting claim 10, wherein the program is designed to plan 14. The toolpath calculation program according to any one of claims 6 to 13, wherein in the toolpath calculation step, the toolpath is calculated so as to be unicursal. The unicursal writing includes an end point designation step of designating an end point of the tool path as a starting point, a moving step of moving to the end point on the opposite side, and a non-connection judgment of judging whether the unconnected end point remains. 15. The tool path calculation program according to claim 14, wherein the step of connecting to the closest end point from the current end point when the unconnected end point remains. 16. The toolpath calculation program according to any one of claims 6 to 15, wherein the toolpath calculation is performed based on a NURBS curve.