JPH05303413A - Method for generating shape data - Google Patents

Abstract

PURPOSE:To automatically find out the shape data of a draft face of a metallic mold so that the metallic mold can easily be extracted and the generation of defects in a product shape molded by the metallic mold is reduced. CONSTITUTION:The shape of the surface SM of a metal mold model and the shape of a reference parting line SCP are stored, a draft angle alpha deg. and a draft length 1 are determined, an optional point P is determined on the SCP, a model shape cutting plane PLn passing a point P vertical to the tangent vector of a prescribed axis Z direction component 0 is found out, and an intersecting line SCS between the PLn and the surface SM of the model is found out. Then a tangent inclined to the SCS by alpha deg. is found out, the contact Q' and a point R' on the tangent which is separated from the contact Q' by the prescribed length 1 are circulated around the SCP and stored, prescribed interpolation curves SCQ', SCR' are respectively found out from the whole sequence of contacts Q' and the whole sequence of points R' and stored, and an interval between the interpolation curve SCQ' and its corresponding interpolation curve SCR' is interpolated by a prescribed interpolation curve to find out and store a draft face SFQ'.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of creating shape data required as NC data for a machine tool with a numerical control (NC) device, and particularly to a draft for facilitating removal of a die when opening the die. The present invention relates to a method of creating shape data for machining attached dies.

[0002]

Molds are typically mounted on machines such as die casting machines or plastic injection molding machines. Then, aluminum or zinc is used in a die-casting machine, and a plastic raw material is injected in a plastic injection-molding machine under pressure to be injected and injected into a cavity inside a mold attached to each machine. Alternatively, the plastic raw material is cooled and solidified for a predetermined time, and then the mold is opened to manufacture a die-cast product or a plastic product having a desired shape according to the shape of the cavity inside the mold. The mold is used for such a purpose. However, if the depth of the mold is deep and the vertical portion is long, there is a problem in that the cooled and solidified die cast product or plastic product is difficult to separate from the mold and the mold is difficult to remove. In addition, there is a problem that burrs are generated due to a defective mold shape during the injection and injection.

In view of the above, experts in the field of manufacturing molds usually make a mold with a draft in order to make it easy to draw the mold and reduce the burr. It is empirically known that it is desirable that the angle of this draft be as large as possible. However, in the prior art, there is no method for automatically and unambiguously creating the shape of a drafted metal mold, and it is empirically inferred by a specialist in the field of manufacturing a metal mold to make a drafted metal mold. The shape of the mold was decided.

[0004]

The shape of the die with a draft thus created is optimal because the shape precision of the die varies depending on the experience and individual differences of experts in the field of producing the die. There is a problem that the mold does not open well because of no draft and that many defects occur in the product shape molded by the mold. Further, even if the optimum shape can be completed, there is a problem that a great amount of time and labor is spent until then.

Therefore, an object of the present invention is to achieve a more optimal shape which does not have the above-mentioned problems, that is, the shape of the product formed by the opening of the mold is less likely to be defective. It is an object of the present invention to provide a shape data creation method for automatically obtaining the shape of a die having a draft without spending time and labor.

[0006]

A method for creating shape data of a die having a draft according to the present invention which achieves the above-mentioned object is S
A computer stores the shape data of M (surface model) and the shape data of a parting line (parting line) of a reference mold, and a predetermined draft angle and a predetermined draft length are calculated from the SM shape data. The draft surface is automatically obtained.

FIG. 1 is a flow chart of the basic processing routine of the method according to the present invention. The shape data creation method of the present invention is a shape data creation method for creating shape data of a draft plane of a mold for manufacturing the model from a surface SM shape of a given model, and Shape data of model surface SM and reference dividing line SCP of the mold
3D Cartesian coordinate system X, in which the shape data of
It is stored as data in Y and Z, and the draft angle α °,
The first step of determining the draft length l and the reference dividing line SCP
A model shape that determines an arbitrary point P on the point P, is perpendicular to the vector direction on the plane XY of the predetermined axis Z direction component 0 in the three-dimensional Cartesian coordinate system X, Y, Z of the tangent vector at the point P and passes through the point P A second step of obtaining and storing the cutting plane PLn;

The third step of obtaining and storing the line of intersection SCS between the model shape cutting plane PLn and the surface SM of the model, and the line of intersection S
A tangent line having a draft angle α ° is drawn on CS, a contact point Q ′ on the tangent line is obtained, and a point R ′ having a draft angle α ° and a draft length l apart is obtained from the contact point Q ′. 'And point R'
And a single step around the reference dividing line SCP and store as data in the three-dimensional Cartesian coordinate system X, Y, Z, and a predetermined interpolation curve S from all the obtained point series of each contact Q ′.
A predetermined interpolation curve S is obtained from the entire point sequence of each point R ′ for which CQ ′ is obtained.
And a fifth step of obtaining and storing CR ′, and a sixth step of obtaining a draft surface SFQ ′ by interpolating between the interpolation curve SCQ ′ and the corresponding interpolation curve SCR ′ with a predetermined interpolation curve. , Consisting of.

In the shape data creating method according to the present invention, in the fourth step, the intersection line SCS is further transformed from the three-dimensional orthogonal coordinate system X, Y, Z into the plane coordinate system HL-VL, and the plane coordinate system HL. The intersection line SCS ′ obtained by rotating the intersection line SCS around the origin on the −VL clockwise by the draft angle α ° has the maximum value in the predetermined axis HL direction on the plane coordinate system HL-VL. The point Q is obtained, the point R is obtained by subtracting the draft length l from the point Q in the direction of the other axis VL on the plane coordinate system HL-VL, and further the plane coordinate system HL-VL.
The point Q "and the point R" obtained by rotating the intersection line SCS 'around the origin in the counterclockwise direction by the draft angle α ° and returning it are obtained as the point Q "and the point R". It is characterized in that "and point R" are coordinate-converted into a three-dimensional orthogonal coordinate system X, Y, Z to obtain point Q'and point R ', respectively.

The method for creating shape data according to the present invention further includes a method for creating a mold based on the shape data of the draft surface SFQ 'of the mold obtained by the above-described method and the shape data of the dividing surface SFP of the mold given in advance. In the method of creating the shape data of a new dividing line, the tangent line of the intersecting line SCS passing through the points R ″ and Q ″ obtained by the above method and the plane coordinate system HL-V passing through the point P
It is characterized in that an intersection point P ′ of a straight line parallel to the HL axis in L is obtained, and the division line SCP ′ is obtained by making one round around the reference division line SCP to obtain a new division line SCP ′ of the die. ..

In the shape data creating method according to the present invention, further, in a pair of molds including an upper mold and a lower mold, the draft surface of each mold is obtained by the above-mentioned method, and one draft surface SFQ _{1 obtained.} In the method of creating the shape data of the new parting line of the mold from the shape data of 'and the shape data of the other draft surface SFQ ₂ ', the model shape cutting of one mold obtained by the above method Point R ₁ ″ on plane PLn
And the tangent to the intersection line SCS ₁ passing through the point Q ₁ ″ and the tangent to the intersection line SCS ₂ passing through the point R ₂ ″ and the point Q ₂ ″ of the other mold, and the reference dividing line SCP It is characterized in that the dividing line SCP ′ is obtained by making one turn around the line and is set as a new dividing line SCP ′ of the mold.

The shape data creating method according to the present invention further includes a shape data creating method for creating shape data of a mold dividing surface from shape data of a mold dividing line obtained by any one of the above methods. Arbitrary points P'are determined on the lines of the new parting line SCP 'of the mold, and the points R'corresponding to each of the points P'and separated by a predetermined width w in the predetermined normal direction.
Then, a predetermined interpolation curve SCR 'is obtained by continuously connecting the points R'as a series of points, and a predetermined interpolation curve is provided between the new dividing line SCP' and the corresponding interpolation curve SCR '. It is characterized in that the die dividing surface SFP is obtained by interpolation.

[0013]

According to the shape data creating method of the present invention, in the shape data creating method for creating the shape data of the draft surface of the mold, the shape of the surface SM of the model and the shape of the reference dividing line SCP of the mold given in advance. Is stored as data, the draft angle α ° and the draft length l are determined, and the reference dividing line SCP
A model shape that determines an arbitrary point P above and passes through a point P perpendicular to the vector direction on the plane XY of the predetermined axis Z direction component 0 in the three-dimensional Cartesian coordinate system X, Y, Z of the tangent vector at the point P The cutting plane PLn is obtained and stored, the intersection line SCS between the model shape cutting plane PLn and the surface SM of the model is obtained and stored, and a tangent line having a draft angle α ° is drawn on the intersection line SCS and a contact point Q ′ on the tangent line. And a point R ′ having a draft angle α ° and a draft length l away from the contact point Q ′ is a reference dividing line S.
Obtained by making one round around CP, three-dimensional Cartesian coordinate system X, Y,
A predetermined interpolation curve SCQ ′ is obtained from all the point sequences of the obtained contact point Q ′ and a predetermined interpolation curve SCR ′ is obtained and stored from all the point points of the obtained point R ′.
The shape data of the draft surface SFQ 'is obtained by interpolating between Q'and the corresponding interpolation curve SCR' with a predetermined interpolation curve.

In the shape data generating method according to the present invention, the intersection line SCS is further converted from the three-dimensional Cartesian coordinate system X, Y, Z into the plane coordinate system HL-VL, and the plane coordinate system HL-VL.
The point Q having the maximum value in the predetermined axis HL direction on the plane coordinate system HL-VL on the intersection line SCS ′ obtained by rotating the intersection line SCS clockwise around the origin by the draft angle α °. The point R obtained by subtracting the draft length l from the point Q in the direction of the other axis VL on the plane coordinate system HL-VL is obtained, and the intersection line S around the origin in the plane coordinate system HL-VL is obtained.
The respective points Q and R obtained by rotating CS 'counterclockwise by the draft angle α ° and returning it are obtained as points Q ″ and R ″, and points Q ″ and R ″ are 3 Dimensional Cartesian coordinate system X, Y,
The coordinates are converted into Z to obtain points Q ′ and R ′.

[0015]

FIG. 2 is a flow chart of a processing routine of a method for obtaining a draft surface of a mold from SM shape data. An embodiment of a method for obtaining a draft surface of a mold according to the present invention will be described below with reference to FIG. 2 and other drawings. The numbers following S in the figure indicate step numbers.

FIG. 3 is a partially cutaway perspective view of a model whose surface is composed of a plurality of surface patches. The shape of each surface patch in FIG. 3 is generally represented by a predetermined interpolation curve such as a three-dimensional Bezier curve or a spline curve. In the embodiment of the present invention, the function f based on the u and v parameters converted into the three-dimensional coordinate systems X, Y and Z orthogonal to each other.
Expressed as (u, v). In addition, the model surface will be referred to as SM
It is simply expressed as (surface model).

In the first stage, for example, the SM shown in FIG.
The shape data and the shape data of the reference dividing line SCP are stored, and a draft angle α ° and a draft length 1 described later are set (step S1). That is, (1) For the SM shape composed of a plurality of surface patches,
The three-dimensional orthogonal coordinate system X, Y, Z of each surface patch is stored as data by a function of u and v parameters (memory of such a shape is called modeling). (2) The shape data of the reference dividing line SCP interpolated by a predetermined interpolation curve is stored as data of the three-dimensional orthogonal coordinate system X, Y, Z. (3) Set each data of the draft angle α to the SM of the die and the draft length l.

FIG. 4 is a diagram showing a plane cut at a point on the reference dividing line, and FIG. 5 is a diagram showing the diagram shown in FIG. 4 projected on the XY plane. In the second stage, an arbitrary point P is determined on the reference dividing line SCP shown in FIGS. 4 and 5 (step S2), and 3 of the tangent vector Vi (x, y, z) of the reference dividing line SCP at the point P is determined. Vector Viz0 on the XY plane (shown in FIG. 5) of the predetermined axis Z direction component 0 in the dimensional orthogonal coordinate system X, Y, Z, that is, the tangent vector Vi (x,
A model shape cutting plane PLn passing through a point P perpendicular to the direction of the vector in which the Z component of (y, z) is 0 is obtained and stored (step S3). The model shape cutting plane PLn is parallel to the Z axis.

In the third stage, the model shape cutting plane P
The line of intersection SCS between Ln and the surface SM of the model is determined and stored (step S4). That is, the intersection line SCS is obtained by cutting the surface patch of the shape model SM with the model shape cutting plane PLn.

FIG. 6 is an explanatory diagram of how to find points on the model that characterize the draft surface and their corresponding points. In the fourth stage, the contact point Q ′ on the surface SM of the model having the draft angle α ° from the intersection line SCS and the point R ′ having the draft angle α ° and the draft length l apart from the contact point Q ′ are divided into the reference divisions. Line SC
One round is made around P, and the data is stored as data in the three-dimensional rectangular coordinate system X, Y, Z. Specifically, as shown in FIG. 6, the intersection line SCS on the model shape cutting plane PLn is H
Expressed in the L-VL coordinate system, (1) The intersection line SCS is transformed into the HL-VL coordinate system, and H
The intersection line SCS is rotated around the origin of the L-VL coordinate axis by a draft angle α ° to obtain the intersection line SCS ′ (step S
5). (2) The point Q having the maximum value of the HL (X) coordinates on the intersection line SCS 'is obtained (step S6). (3) The point R is obtained by subtracting the VL (Y) coordinate of the point Q by the draft length l (step S7). (4) The obtained Q and R are returned by rotating the intersection line SCS ′ around the origin of the HL-VL coordinate axis by a draft angle α °.
Q "and R" are obtained in the HL-VL coordinate system, and the obtained Q ",
R ′ is transformed into a three-dimensional Cartesian coordinate system X, Y, Z and Q ′,
R'is obtained and stored (step S8).

The point P is moved to another point P on the reference dividing line SCP (step S9), and it is determined whether or not one round has been completed around the reference dividing line SCP (step S10). When the determined result is NO, the process returns to step S2, and from step S2 to step S10 until the determined result becomes YES.
Is repeatedly executed, and when the determined result is YES, the process proceeds to step S11.

FIG. 7 is a diagram showing a process of creating a draft surface from the characteristic points of the draft surface. In the fifth stage,
As shown in FIG. 7, a contact curve SCQ ′, which is a predetermined interpolation curve, is obtained and stored from all the obtained point sequences of each contact Q ′ (step S11), and a predetermined point sequence is obtained from all obtained point sequences of each point R ′. A contact extension corresponding curve SCR 'which is an interpolation curve is obtained and stored (step S12).

In the sixth step, the contact curve SCQ '
The contact extension corresponding curve SCR ′ corresponding to the above is interpolated by a predetermined interpolation curve to obtain a draft surface SFQ ′ (step S
13), the obtained draft surface SFQ 'is stored as the final draft surface (shown in FIG. 7) (step S1).
4).

In the embodiment of the present invention described above, the shape data of the draft surface of the mold is set on the basis of the mold dividing line (reference dividing line SCP) which is a characteristic line conforming to the shape of the mold model. As a method of creating other shape data of the present invention, the draft surface S obtained by the above-described method is used.
FQ 'and a division plane S obtained by a predetermined method
Find the line of intersection with the FP, and divide that line into the mold parting line SCP '
Then, an arbitrary point P'is determined on the dividing line SCP ', each point R'which is separated by a predetermined width w in the predetermined normal direction in correspondence with each of the points P'is obtained, and each point A predetermined interpolation curve SCR 'is continuously connected as a point sequence of R', and a predetermined interpolation curve is provided between the dividing line SCP 'and the corresponding interpolation curve SCR' to divide the mold. There is a method of obtaining the surface SFP and creating shape data to be used as the divided surface of the mold.

FIG. 8 is a flow chart of a processing routine of a method for obtaining a divided surface continuous with the draft surface. Hereinafter, a method of obtaining a divided surface continuous with the draft surface will be described with reference to FIG. 8 and other drawings. The numbers following S in the figure indicate step numbers. The SM shape data and the shape data of the reference dividing line SCP are stored, and the draft angle α
And the width w (offset width) of a predetermined division surface are set (step S21). That is, (1) For the SM shape composed of a plurality of surface patches,
The three-dimensional orthogonal coordinate system X, Y, Z of each surface patch is stored as data by a function of u and v parameters. (2) The shape data of the reference dividing line SCP interpolated by a predetermined interpolation curve is stored as data of the three-dimensional orthogonal coordinate system X, Y, Z. (3) Set the data of the draft angle α ° to the SM of the die. (4) Set the data of the width w of a predetermined divided surface.

Next, a data table of points Q'on the tangent line having a draft angle α ° to the SM of the mold and corresponding division points R '(described later) is initialized (step S22). next,
An arbitrary point P is determined on the reference dividing line SCP (step S
23), the HL-VL plane that passes through the point P and is perpendicular to the XY projection curve of the reference division line SCP (the point P in the X, Y, Z coordinate system
A plane passing through a point P perpendicular to the vector with the Z component of the tangent vector at 0), ie, the model shape cutting plane P
Ln is obtained (step S24). Next, the line of intersection SCS between the model shape cutting plane PLn and the surface SM of the model is determined and stored (step S25). That is, the intersecting line SCS is the surface patch of the shape model SM, and the model shape cutting plane PLn
It is obtained by cutting with.

FIG. 9 is an explanatory diagram of a method for obtaining a new dividing line from the draft surface. As shown in the figure, the contact point Q ′ on the surface SM of the model having the draft angle α ° from the intersection line SCS
Is calculated (step S26). Then, an intersection point P ′ between a straight line passing through the point P and parallel to the HL axis and a tangent line from the contact point Q ′ to the intersection line SCS having the draft angle α ° is obtained (step S27). This point P'becomes a division point forming a new division line SCP '. Next, all points P on the reference dividing line SCP
It is determined whether or not one round has been made (step S28),
When the determined result is NO, the process returns to step S23,
Steps S23 to S are performed until the determined result is YES.
28 is repeatedly executed, and when the determined result is YES, the process proceeds to step S29.

FIG. 10 is a view showing a division surface continuous with the draft surface. The figure shows the draft curve SCQ ', the dividing line S
CP ', division corresponding curve SCR', draft surface SFQ ',
The division plane SFP is shown. After step S28, a draft curve SCQ 'which is a predetermined interpolation curve is obtained from all the obtained point sequences of each contact point Q'and stored (step S29), and a predetermined point is obtained from all the obtained point sequences of each point P'. An interpolation curve SCP ', that is, a new dividing line is obtained and stored (step S30).
The draft line SFQ 'is obtained by interpolating between the draft curve SCQ' and the corresponding new dividing line SCP 'with a predetermined interpolation curve (step S31).
P'is offset by XY by a predetermined length w, and the division corresponding curve S
CR 'is obtained (step S32), and the corresponding point XY offset by the predetermined length w of the intersection P'is R'. The predetermined length w corresponds to the divided surface width. New dividing line S
CP ', division corresponding curve SCR', and new division plane SF
P is calculated (step S33), and the draft surface SFQ 'and the division surface SFP are stored (step S34).

As another method for creating shape data of the present invention, the draft slope surfaces SFQ ₁ ′ and SFQ ₂ ′ of each die in a pair of dies including an upper die and a lower die are formed by the above-mentioned method according to the present invention. Two draft planes SF obtained by
Q ₁ 'and SFQ _2' seek line of intersection, the intersection line a new dividing line SCP mold 'and, dividing line SCP of the obtained mold'
, An arbitrary point P ′ is determined on the line, and each point R ′ is obtained corresponding to each point P ′ and separated by a predetermined width w in the predetermined normal direction, and is continuously formed as a point sequence of the respective points R ′. To obtain a predetermined interpolation curve SCR ′, and to interpolate between the division line SCP ′ and the corresponding interpolation curve SCR ′ with a predetermined interpolation curve to obtain a die dividing surface SFP to obtain a die There is a method of creating shape data for a new division plane.

FIG. 11 is a flow chart of a processing routine of a method for obtaining a divided surface continuous with the draft surface of a pair of molds. Hereinafter, a method for obtaining a divided surface continuous with the draft surface of the pair of molds will be described with reference to FIG. 11 and other drawings. The numbers following S in the figure indicate step numbers. The SM shape data and the shape data of the reference dividing line SCP are stored, and the upper draft angle α ₁ °, the lower draft angle α ₂ °, and the width w (offset width) of a predetermined dividing surface.
Is set (step S41). That is, (1) For the SM shape composed of a plurality of surface patches,
The three-dimensional orthogonal coordinate system X, Y, Z of each surface patch is stored as data by a function of u and v parameters. (2) The shape data of the reference dividing line SCP interpolated by a predetermined interpolation curve is stored as data of the three-dimensional orthogonal coordinate system X, Y, Z. (3) Set each data of the upper draft angle α ₁ ° and the lower draft angle α ₂ ° to the SM of the mold. (4) Set the data of the width w of a predetermined divided surface.

Next, the upper draft angle α _{1 of the} die to the SM
A data table of a point Q ₁ 'on a tangent line having °, a point Q ₂ ' on a tangent line having a lower draft angle α ₂ ° and a division corresponding point R '(described later) is initialized (step S4).
2). Next, an arbitrary point P is determined on the reference dividing line SCP (step S43), and passes through the point P, and X of the reference dividing line SCP is determined.
The HL-VL plane perpendicular to the Y projection curve (the plane passing through the point P perpendicular to the vector with the Z component of the tangent vector at the point P in the X, Y, Z coordinate system being 0), that is, the model shape cutting plane PLn is obtained. (Step S44). next,
An intersection line SCS between the model shape cutting plane PLn and the surface SM of the model is obtained and stored (step S45). That is,
The intersection line SCS is obtained by cutting the surface patch of the shape model SM along the model shape cutting plane PLn.

FIG. 12 is an explanatory diagram of a method of obtaining a new dividing line from the draft surface of a pair of molds. As shown in the figure,
The contact point Q ₁ 'on the surface SM of the model having the upper draft angle α ₁ ° is obtained from the intersection line SCS (step S46).
The contact point Q ₂ 'on the surface SM of the model having the lower draft angle α ₂ ° is obtained from the intersection line SCS (step S47).
The tangent line from the contact point Q ₁ 'to the intersection line SCS having the upper draft angle α ₁ ° and the lower draft angle α from the contact point Q ₂ '
An intersection point P ′ with a tangent to the intersection line SCS having ₂ ° is obtained (step S48). This point P'is the new dividing line SC
It becomes a division point forming P ′. Next, it is determined whether or not one round has been made around all the points P on the reference dividing line SCP (step S49). If the determined result is NO, step S4
Return to step 3, until the determined result is YES, step S
43 to S49 are repeatedly executed, and the determined result is YE.
When the result is S, the process proceeds to step S50.

FIG. 13 is a view showing a division surface continuous with the draft surface of the pair of molds. The figure shows the upper draft curve S
CQ ₁ ′, lower draft curve SCQ ₂ ′, new dividing line SCP ′, dividing corresponding curve SCR ′, upper draft surface SF
Q ₁ ′, lower draft surface SFQ ₂ ′, and division surface SFP are shown. The next step S49, the upper vent from the entire sequence of points of each contact Q ₁ 'which Motoma' a predetermined interpolation curve slope curve SCQ
₁ 'asking stored (step S50), Motoma' were each contact Q _2' stores seeking lower draft curve SCQ ₂ 'is a predetermined interpolation curves from all points sequence of (step S51), Motoma' were each point A predetermined interpolation curve SCP ', that is, a new dividing line is obtained from all the point sequences of P'and stored (step S5).
2). An upper draft surface SFQ ₁ ′ is obtained by interpolating between the upper draft curve SCQ ₁ ′ and the corresponding new dividing line SCP ′ by a predetermined interpolation curve (step S 5
3) Obtain a lower draft surface SFQ ₂ ′ by interpolating between the lower draft curve SCQ ₂ ′ and the corresponding new dividing line SCP ′ with a predetermined interpolation curve (step S5).
4) The new dividing line SCP 'is XY offset by a predetermined length w to obtain a dividing correspondence curve SCR' (step S5).
5). Here, the corresponding point which is XY offset by the predetermined length w of the intersection point P ′ is R ′. New dividing line SCP 'a division corresponding curve SCR' than seeking new division surface SFP (step S56), the upper draft surface SFQ ₁ ', the lower draft surface SFQ _2' stores and dividing plane SFP (step S57).

[0034]

As described above, according to the shape data generating method of the present invention, the shape data of the draft surface of the mold can be obtained without depending on the experience and individual differences of the experts in the field of manufacturing the mold. Since it can be automatically generated, it is possible to easily remove the mold and reduce the occurrence of defects in the shape of the product molded by the mold. Furthermore, according to the shape data creation method of the present invention,
Even if the model has any shape including a vertical surface, the shape data of the draft surface of the mold can be uniquely automatically generated. Furthermore, according to the shape data creation method of the present invention, since the shape data of the draft surface of the mold is created based on the parting line of the mold, which is a characteristic line conforming to the shape of the model of the mold, A draft surface matching the shape of the model can be obtained.

[Brief description of drawings]

1 is a flow chart of a basic processing routine of a method according to the present invention.

FIG. 2 is a flowchart of a processing routine of a method for obtaining a draft surface of a die from SM shape data.

FIG. 3 is a partially cutaway perspective view of a model whose surface is composed of a plurality of surface patches.

FIG. 4 is a diagram showing a plane cut at a point on a reference dividing line.

FIG. 5 is a diagram obtained by projecting the diagram shown in FIG. 4 on an XY plane.

FIG. 6 is an explanatory diagram of how to find points on a model that characterize a draft surface and their corresponding points.

FIG. 7 is a diagram showing a process of creating a draft surface from feature points of the draft surface.

FIG. 8 is a flow chart of a processing routine of a method for obtaining a division surface that is continuous with a draft surface.

FIG. 9 is an explanatory diagram of a method of obtaining a new dividing line from a draft surface.

FIG. 10 is a view showing a division surface continuous with a draft surface.

FIG. 11 is a flow chart of a processing routine of a method for obtaining a divided surface that is continuous with a draft surface of a pair of molds.

FIG. 12 is an explanatory diagram of a method of obtaining a new dividing line from a draft surface of a pair of molds.

FIG. 13 is a diagram showing a division surface that is continuous with a draft surface of a pair of molds.

[Explanation of symbols]

 SCP ... Standard division line SCP '... New division line PLn ... Model shape cutting plane SCS ... Intersection line SCQ' ... Contact curve SCR '... Contact extension corresponding curve SFQ' ... Draft surface SM ... Model surface shape (surface model) SFP ... Dividing surface l ... Draft length w ... Dividing surface width α ... Draft

Claims (5)

[Claims] 1. A shape data creating method for creating shape data of a draft surface of a mold for producing a model from a given model shape, comprising: shape data of the model surface SM and the metal given in advance. A first step of storing shape data of a mold reference dividing line SCP as data in a three-dimensional orthogonal coordinate system X, Y, Z orthogonal to each other and determining a draft angle α and a draft length l; An arbitrary point P is determined on the line SCP, and the point P
In the three-dimensional Cartesian coordinate system X, Y,
A model shape cutting plane PLn perpendicular to the vector direction on the plane of the predetermined axis Z direction component 0 in Z and passing through the point P
And a third step of obtaining and storing a line of intersection SCS between the model shape cutting plane PLn and the surface SM of the model, and a tangent line having the draft angle α on the line of intersection SCS. The contact point Q'on the tangent line is obtained, the point R'having the draft angle α and separated from the contact point Q'by the draft length l is found, and the contact point Q'and the point R'are respectively obtained. A fourth step of making one turn around the reference dividing line SCP and storing as data in the three-dimensional Cartesian coordinate system X, Y, Z, and a predetermined interpolation curve SCQ 'from all points of each contact point Q'.
Is a predetermined interpolation curve SCR ′ from all points of each point R ′.
A fifth step of respectively obtaining and storing the above, and the interpolation curve SCR ′ corresponding to the interpolation curve SCQ ′.
And a draft surface SFQ '
And a sixth step of memorizing and storing the shape data. 2. In the fourth step, the intersection line SCS is converted from the three-dimensional Cartesian coordinate system X, Y, Z into a plane coordinate system HL-VL.
At the intersection line SCS ′ obtained by rotating the intersection line SCS clockwise around the origin on the plane coordinate system HL-VL by the draft angle α. A point Q having the maximum value in the direction of the predetermined axis HL on VL is obtained, and a point R obtained by subtracting the draft length 1 from the point Q in the direction of another axis VL on the plane coordinate system HL-VL is obtained. Respective points Q and R obtained by rotating the intersection line SCS ′ counterclockwise around the origin in the plane coordinate system HL-VL by the draft angle α and returning the points R to Q are the points Q. "And point R", respectively, the points Q "and R" are coordinate-converted into the three-dimensional Cartesian coordinate system X, Y, Z to obtain points Q'and R ', respectively, and the points Q'
2. The shape data creation method according to claim 1, wherein the point R ′ and the point R ′ are obtained by making one turn around the reference dividing line SCP and stored as data in the three-dimensional orthogonal coordinate system X, Y, Z. 3. The shape of a new parting line of the mold from the shape data of the draft surface SFQ ′ of the mold obtained by the method of claim 2 and the shape data of the parting surface SFP of the mold which is given in advance. In a method of creating data, an intersection point P ′ of a tangent line of the intersection line SCS passing through the point R ″ and the point Q ″ and a straight line passing through the point P and parallel to the HL axis in the plane coordinate system HL-VL. Then, the shape data creating method is characterized in that the dividing line SCP ′ is obtained by making one round around the reference dividing line SCP to obtain a new dividing line SCP ′ of the mold. 4. A draft surface of each die of a pair of dies consisting of an upper die and a lower die is obtained by the method according to claim 2, and the shape data of one of the obtained draft surfaces SFQ ₁ 'is obtained. In the method of creating the shape data of a new parting line of the mold from the shape data of the other draft surface SFQ ₂ ′, a point R ₁ ″ and a point Q ₁ on the model shape cutting plane PLn of the _one mold. The intersection point P ′ between the tangent to the intersection line SCS ₁ passing through “the other die R ₂ ” and the tangent to the intersection line SCS ₂ passing through the point Q ₂ ”is obtained, and the intersection P ′ is provided around the reference dividing line SCP. 1
The dividing line SCP 'is obtained by going around and the new dividing line SC of the die is obtained.
A method for creating shape data, wherein P'is set. 5. A shape data creating method for creating shape data of a die dividing surface from shape data of die dividing lines obtained by the method according to claim 3 or 4, wherein the obtained die An arbitrary point P'is determined on the line of the new division line SCP ', each point R'is determined in correspondence with each of the points P', and is separated by a predetermined width w in the predetermined normal direction. A predetermined interpolation curve SCR 'is continuously connected as a point sequence of', and a new interpolation line SCR 'and the corresponding interpolation curve SCR' are interpolated with a predetermined interpolation curve to obtain a mold. A shape data creation method characterized by obtaining a division plane SFP.