JP2859025B2 - Shape data creation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preparing shape data required as NC data of a machine tool having a numerical control (NC) device, and more particularly, to a method of forming a draft for facilitating removal of a mold when the mold is opened. The present invention relates to a method of creating shape data for attaching a die.

[0002]

2. Description of the Related Art A mold is generally mounted on a machine such as a die casting machine or a plastic injection molding machine. Then, aluminum or zinc is injected into the cavity inside the mold attached to each machine by pressing and melting the aluminum or zinc in the die casting machine and the plastic raw material in the plastic injection molding machine. Alternatively, the plastic material is cooled and solidified for a predetermined time, and then the mold is opened to produce 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, when the depth of the mold is deep and the vertical portion is long, there is a problem 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. Further, there is a problem that burrs are generated due to a defective mold shape during the injection and injection.

[0003] In view of the above, specialists in the field of manufacturing a mold usually provide a draft to the mold in order to make it easier to remove the mold and to reduce the burrs. It is empirically known that the angle of the draft is desirably as large as possible. However, in the prior art, there is no method for automatically and uniquely creating the shape of a drafted mold. The shape of the mold was determined.

[0004]

The shape of the mold with draft angle formed as described above has a variation in the shape accuracy due to the experience and individual differences of the specialists in the field of manufacturing the mold, and the shape is optimal. There is a problem in that the mold does not open well due to a moderate draft angle, and many defects occur in the product shape formed by the mold. Further, there is a problem that even if an optimum shape can be completed, a great deal of time and labor is required until then.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to eliminate the above-mentioned problems, that is, to open a mold well and to minimize the occurrence of defects in a product shape formed by the mold, and to achieve a more optimal shape. An object of the present invention is to provide a shape data creating method for automatically obtaining a shape of a mold with a draft without spending time and effort.

[0006]

According to the present invention, there is provided a method for producing shape data of a mold having a draft, which achieves the above object.
The shape data of the M (surface model) and the shape data of the parting line (parting line) of the mold as a reference passing outside the SM are stored in a computer, and the division of the mold as the reference is performed. A tangent line having a draft angle is drawn from the line to the shape of the SM, and a point that is separated from the contact point by a predetermined distance along the tangent line toward the reference mold dividing line from the contact point is determined. This is to automatically determine the draft surface of the mold by making one round around the dividing line of the mold.

FIG. 1 is a flowchart of a basic processing routine of the method according to the present invention. The shape data creating method according to the present invention is a shape data creating method for creating shape data of a draft surface of a mold for manufacturing a given model from the surface SM shape of the given model. A first stage in which shape data of a reference dividing line SCP of the mold passing through a position separated outward from the model surface SM is given in advance and stored as data in a mutually orthogonal three-dimensional orthogonal coordinate system X, Y, Z. And the reference dividing line SCP
An arbitrary point P is determined above, and a model shape which is perpendicular to the vector direction on the plane XY of the predetermined axis Z direction component 0 in the three-dimensional orthogonal coordinate system X, Y, Z of the tangent vector at the point P and passes through the point P A second step of determining and storing the cutting plane PLn;
A third step of obtaining and storing an intersection line SCS between the model shape cutting plane PLn and the surface SM of the model, and a contact point Q ′ obtained by drawing a tangent from the point P on the intersection line SCS by using a reference division line S
Obtained by making one round around the CP, the three-dimensional rectangular coordinate system X, Y,
A fourth step of storing as data in Z, a fifth step of obtaining and storing a predetermined interpolation curve SCQ ′ from all the point sequences of each contact point Q ′, and a step of storing the interpolation curve SCQ ′ and the corresponding reference division line SCP. A sixth step of interpolating the space with a predetermined interpolation curve to obtain and store the draft surface SFQ ′.

[0008]

The shape data creating method according to the present invention provides a shape data creating method for creating shape data of a draft surface of a mold for manufacturing a mold model. The reference division line SCP of the shape and the mold is stored as data, an arbitrary point P is determined on the reference division line SCP, and a tangent vector at the point P is defined in a predetermined axis Z direction in a three-dimensional orthogonal coordinate system X, Y, Z. A model shape cutting plane PLn which is perpendicular to the vector direction on the plane XY of the component 0 and passes through the point P is obtained and stored, an intersection line SCS between the model shape cutting plane PLn and the model surface SM is obtained and stored, and the intersection line SC is obtained.
A contact point Q ′ obtained by drawing a tangent to the intersection line SCS from the point P on S is determined as a point in the three-dimensional orthogonal coordinate system X, Y, Z by making one round around the reference division line SCP, and stored. A predetermined interpolation curve SCQ 'is obtained and stored from the obtained all point sequence of each contact point Q', and the interpolation surface between the interpolation curve SCQ 'and the corresponding reference division line SCP is interpolated by the predetermined interpolation curve to obtain a draft surface. Shape data of SFQ 'is obtained.

[0009]

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

FIG. 3 is a partially broken perspective view of a model whose surface is composed of a plurality of surface patches. Each shape of the 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, a function f based on u and v parameters converted into a mutually orthogonal three-dimensional coordinate system X, Y, Z
Expressed by (u, v). In addition, the surface of the model is referred to as SM
(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 passing through the position separated outside the SM are stored (step S1). That is, (1) For an 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 based on a function of u, v parameters (such shape storage is called modeling). (2) The shape data of the reference division line SCP interpolated by the predetermined interpolation curve is stored as data of the three-dimensional orthogonal coordinate system X, Y, Z.

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

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

FIG. 6 is an explanatory view of a method of obtaining a contact point by drawing a tangent line to the SM from a point on the reference division line. In a fourth step, an intersection line SCS is obtained from a point P on the reference division line SCP.
Then, a tangent line is drawn and the contact point Q 'is obtained and stored. Specifically, as shown in FIG. 6, the intersection line SCS on the model shape cutting plane PLn is expressed in the HL-VL coordinate system. (1) The intersection line SCS is coordinate-transformed into the HL-VL coordinate system, and the point P From the three-dimensional orthogonal coordinate system X, Y, Z to the HL-VL coordinate system to obtain a point P ″ (step S5). (2) A line segment from the point Q ″ on the intersection line SCS to the point P ″ pull,
As described later, the maximum value of the inclination with respect to the HL axis is obtained, and the obtained point is set as Q "(Step S6). (3) The point Q" is converted from the HL-VL coordinate system into a three-dimensional orthogonal coordinate system X, Y, Z. And store it as Q ′ (step S
7). (4) The point P is moved to another point P on the reference division line SCP (step S8), and it is determined whether or not one round around the reference division line SCP has been completed (step S9). If the determined result is NO, the process returns to the step S2, and the determined result is Y
Steps S2 to S9 are repeatedly executed until ES is reached, and when the determined result is YES, the process shifts to step S10.

FIG. 7 is a perspective view of a draft surface created by the method according to the present invention. In the fifth stage, as shown in FIG. 7, a contact curve SCQ 'which is a predetermined interpolation curve is obtained from all the sequence of points of each obtained contact Q' and stored (step S1).
0), In the sixth stage, the determined contact curve SCQ ′
And a predetermined interpolation curve between the reference division line SCP and
A draft surface SFQ 'is obtained (step S11), and the obtained draft surface SFQ' is stored as a final draft surface (shown in FIG. 7) (step S12).

FIG. 8 is a flowchart of a processing routine of a method for obtaining a contact point by drawing a tangent line from the point on the reference dividing line to the intersection line. 8 and other drawings, a straight line is drawn from the point Q ″ on the intersection line SCS to the point P ″, and the maximum value of the inclination with respect to the HL axis is obtained. A description will be given of an embodiment of a method for obtaining Q "as Q". FIG. 9 is a diagram showing a tangent vector at a point on one segment of the intersection. As shown in the figure, (1) a point P " Then, the data table of the contact point and the inclination is initialized (step S21). (2) One curve segment SC from a plurality of intersection lines SCS
Sj is extracted (step S22). (3) The curve segment SCSj is divided into n, and each point Qi on the n-divided line segment and a tangent vector TQi ″ at the point Qi are obtained (step S23).

FIG. 10 is a diagram showing an outer product vector at each point on one segment of the intersection line. The figure shows the intersection SCS
Are the outer product vectors Vi and V (i + 1) at the point Qi and the point Q (i + 1). As shown in the figure,
After step S23, the vector P "at the point Qi"
An outer product vector Vi of Qi "and the tangent vector TQi" is obtained (step S24).

Next, the polarities of the outer product vector V (i + 1) obtained in the same manner as the outer product vector Vi are compared to determine whether or not the polarities of the outer product vector Vi and the outer product vector V (i + 1) change (step S25). If the result of the determination is YES, a point Q 'at which the polarity of the outer product vector becomes 0 is obtained by the convergence calculation method (step S26). That is, the point Q divided into two between Qi ″ and Q (i + 1) ″ and further divided into two
(I + 1/2) "in the cross product vector V (i + 1 /
2) is similarly obtained, and when the polarity of the cross product vector V (i + （) is not 0, the polarity of the cross product vector Vi or the cross product vector V (i + 1) is changed to the cross product vector V (i + ／).
Is selected, the outer product vector V (i + 1 の) at the point Q (i + ／) ″ which is further divided into two between the selected outer product vector and the outer product vector V (i + ／), and further divided into two. / 4) are similarly obtained, and their polarities are similarly compared, and Q ′ is repeatedly obtained until the polarity becomes 0 or the length of the divided line segment becomes equal to or less than a predetermined allowable value.

Next, a comparison is made as to whether the gradient of the vector P "Qi" is smaller than the previously obtained data, that is, the data of the gradient stored in the contact table (step S27). , The data of the contact point and the inclination in the data table is updated (step S28), i = i + 1 is set (step S29), and i and n are compared, and the comparison result i
Is smaller than n, the process returns to step S25 and the comparison result i
Steps S25 to S30 are repeated until is not smaller than n, and when the comparison result i is not smaller than n, the process proceeds to the next step S31 (step S3).
0). Also, if the determination result in step S25 is NO, steps S29 and S30 are executed, and
Even when the comparison result is not small at 27, steps S29 and S30 are executed.

FIG. 11 is a diagram showing a tangent point drawn from a point on one segment of the intersection. As shown in the figure,
On the tangent line at which the angle between the direction of the vector P "Q" and the direction of the HL axis is the largest, a contact point Q "at which the outer product vector becomes 0 is obtained. Next, a line segment obtained by dividing the segment SCSj of the intersection line SCS into n Is compared with a line segment connecting the starting point or the ending point of the point P "and the slope of the vector P" Q "to determine whether the slope is small (step S31). Is updated (step S32), and as a result of comparison, when the inclination is small, or after step S32 is completed, it is determined whether or not all segments have been completed (step S33), and the determination result is NO
In the case of, it moves to the next segment (step S34),
Next, returning to step S22, steps S32 to S33 are repeatedly executed until the determination result becomes YES. If the decision result in the step S33 is YES, the data of the contact point Q "is stored (step S35). As described above, the contact point Q" on the intersection line SCS is obtained from P ".

[0021]

As described above, according to the shape data creating method of the present invention, the shape data of the draft surface of the mold can be obtained without depending on the experience and the individual difference of the expert in the field of manufacturing the mold. Can be automatically generated, so that the mold can be easily removed and the occurrence of defects in the product shape formed by the mold can be reduced. Furthermore, according to the shape data creation method of the present invention,
Regardless of the shape of the model including the vertical plane, the shape data of the draft surface of the mold can be uniquely and automatically generated. Further, according to the shape data creating method of the present invention, a reference dividing line passing through a position separated outward from the model surface is given in advance, and the draft surface is determined based on the reference dividing line. Can be easily obtained. If one of the mating dies is obtained in the same manner, the mating portions of the shapes fit neatly.

[Brief description of the drawings]

FIG. 1 is a flowchart 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 mold from SM shape data.

FIG. 3 is a perspective view in which a model whose surface is composed of a plurality of surface patches is partially broken.

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 onto an XY plane.

FIG. 6 is an explanatory diagram of a method of obtaining a contact point by drawing a tangent line to a SM from a point on a reference division line.

FIG. 7 is a perspective view of a draft surface created by the method according to the invention.

FIG. 8 is a flowchart of a processing routine of a method of obtaining a contact by drawing a tangent line from a point on a reference dividing line to an intersection line.

FIG. 9 is a diagram showing a tangent vector at a point on one segment of the intersection.

FIG. 10 is a diagram showing an outer product vector at each point on one segment of the intersection line.

FIG. 11 is a diagram showing a contact point on a tangent line drawn from a point on one segment of the intersection line.

[Explanation of symbols]

 SCP: reference dividing line PLn: model shape cutting plane SCS: intersection line SCQ ': tangent curve SFQ': draft surface SM: model surface shape (surface model)

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-277971 (JP, A) JP-A-63-165971 (JP, A) JP-A-63-165970 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) G05B 19/4097 G05B 19/4103

Claims (1)

(57) [Claims] 1. A shape data creating method for creating shape data of a draft surface of a mold for manufacturing a model from a given model shape, wherein the shape data of the model surface SM and an outer side from the model surface SM are provided. A first stage in which shape data of the reference division line SCP of the mold passing through a position separated from the base is given in advance and stored as data in a three-dimensional orthogonal coordinate system X, Y, Z orthogonal to each other; An arbitrary point P is determined above, and the point P
, The three-dimensional rectangular 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
A third step of obtaining and storing an intersection line SCS between the model shape cutting plane PLn and the surface SM of the model; and obtaining a tangent from the point P on the intersection line SCS. A fourth step of determining the contact point Q 'by making one round around the reference division line SCP and storing the data as data in the three-dimensional orthogonal coordinate system X, Y, Z; A fifth step of obtaining and storing a predetermined interpolation curve SCQ ′ from the above, and the reference division line SCP corresponding to the interpolation curve SCQ ′
Is interpolated by a predetermined interpolation curve to obtain a draft surface SFQ ′.
And storing the shape data.