JP2013200721A - Design method of golf club head and golf head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of obtaining design data of a golf club head suitable for mass production from design plan data having many irregularities.SOLUTION: A finite element model for reproducing a golf club head is generated, and an optimization model is generated by optimization processing. A design parameter of the optimization model is converted to a pixel gradation, and pixel data of the prescribed number of pixels is generated. In each pixel in the image data, averaging processing of the pixel gradation is performed with peripheral pixels. The average pixel gradation of the image data is converted to the design parameter again, an averaged model is generated, and a rib of the golf club head is designed using the averaged model.

Description

  The present invention relates to a golf club head design method and a golf club head.

As a golf club head design method, a golf club head model (finite element model) that reproduces the golf club head is created, and the behavior of the golf club head model is analyzed by changing the design parameters of the golf club head. Thus, various characteristic values are calculated for each design parameter, a characteristic value that is an objective function is evaluated among the characteristic values, and a design parameter that optimizes the objective function is used.
For example, in Patent Document 1, the thickness and specific gravity of the head are exemplified as design parameters, and the center of gravity position and the moment of inertia are exemplified as objective functions.
Further, Patent Document 2 exemplifies the number of reinforcing ribs provided on the back surface of the face surface, the arrangement position, and the like as design parameters, and the maximum value of Mises stress as an objective function.

JP-A-2005-65996 JP 2007-257571 A

  FIG. 11 is an example of design data for a golf club head according to a conventional design method. FIG. 11A shows design plan data obtained by the optimization process of the finite element model. The face portion of the golf club head is divided into 49 regions, and the design parameters (face portion thickness) are divided into the respective regions. Thickness) is set. FIG. 11B shows a shape model of the face portion obtained from FIG. In FIG. 11B, a rib is formed at the position of the dotted line in FIG.

  As shown in FIG. 11B, when the design plan obtained by the design method according to the prior art is faithfully reproduced, a face portion shape having a large number of irregularities (steps) is obtained. Such a golf club head having a large number of irregularities can be produced by both forging and casting. However, there are problems such as a decrease in yield in the mass production process, a decrease in durability due to stress concentration at the level difference, and an increase in production cost due to difficulty in creating a mold, which makes it difficult to achieve mass production. There is a point.

  The present invention has been made in view of the above-described problems of the prior art, and a golf club head design capable of obtaining golf club head design data suitable for mass production from a design plan data having a large number of irregularities. It is an object to provide a method and a golf club head designed using this design method.

  In order to achieve the above object, the present invention generates a finite element model that reproduces a golf club head, changes design parameters in the finite element model, analyzes the behavior of the finite element model, and analyzes the results. A predetermined characteristic value is calculated for each design parameter, an optimization model generating step for generating an optimization model having the design parameter that optimizes the characteristic value, and the design parameter of the optimization model is converted to a pixel level. An image data generation step for converting into a key and generating image data of a predetermined number of pixels, and an averaging step for performing pixel gradation averaging processing with surrounding pixels in each pixel in the image data; An averaged finite element model that reconverts the pixel gradation of the averaged image data into the design parameters to generate an average model. A generation step, wherein the containing and rib design step of designing the ribs of the golf club head using the average model.

According to the present invention, the optimization model obtained by the optimization process is converted into image data, and the averaging process is performed to determine the position and shape of the rib while reducing the degree of unevenness of the face surface. To do. Thereby, design data suitable for mass production can be obtained while improving the performance by the optimization process.
Further, according to the present invention, practical design data can be obtained efficiently, and it is possible to smoothly cope with the mass production of golf club heads.

It is a front view which shows an example of the golf club head used as the object of the design method concerning embodiment. It is a block diagram which shows the structure of the computer 30 for performing the design method concerning embodiment. It is a flowchart which shows the outline | summary procedure of the design method concerning embodiment. It is explanatory drawing which shows the outline | summary procedure of the design method concerning embodiment. It is a flowchart which shows the process sequence of an optimization finite element model production | generation step. It is a figure which shows the state by which the face surface 12 was divided | segmented and set to many area | region a. It is explanatory drawing which shows the outline | summary of the process in an averaging step. It is explanatory drawing which shows the image data before and behind an averaging step. It is a flowchart which shows the process sequence of a rib design step. It is a graph which shows the comparative example of the face deflection area of the golf club head obtained with the design method concerning this Embodiment. It is an example of the design data of the golf club head by the design method concerning a prior art.

  Exemplary embodiments of a golf club head design method and a golf club head according to the present invention will be explained below in detail with reference to the accompanying drawings.

(Embodiment)
FIG. 1 is a front view showing an example of a golf club head that is an object of a design method according to an embodiment.
As shown in FIG. 1, the golf club head 10 includes a face portion 14, a crown portion 16, a sole portion 18, and a side portion 20 and has a hollow structure.
The face portion 14 forms a face surface 12 for hitting a golf ball.
The crown portion 16 is connected to the face portion 14.
The sole portion 18 is connected to the face portion 14 and the crown portion 16.
The side portion 20 is connected to the crown portion 16 and the sole portion 18 and faces the face portion 14.
The golf club head 10 is made of metal, and the metal material of the golf club head 10 is preferably a high strength low specific gravity metal such as a titanium alloy or an aluminum alloy.
Further, the crown portion 16 is provided with a hosel 26 connected to the shaft 28 at a position near the heel 22 on the face surface 12 side.
Further, the toe 24 is located on the opposite side of the golf club head 10 from the heel 22 when the face surface 12 is viewed from the front.

FIG. 2 is a block diagram illustrating a configuration of a computer 30 for executing the design method according to the embodiment.
The computer 30 includes a CPU 32, a ROM 34, a RAM 36, a hard disk device 38, a disk device 40, a keyboard 42, a mouse 44, a display 46, a printer 48, an input / output interface 50, etc. connected via an interface circuit (not shown) and a bus line. have.
The ROM 34 stores a control program and the like, and the RAM 36 provides a working area.

  The hard disk device 38 calculates a design parameter, a characteristic value, and the like of the golf club head 10 using a finite element analysis program for performing a finite element analysis of the golf club head 10 and a simulation result obtained by the finite element analysis program. The program is stored. This kind of calculation program is arbitrary, such as using a dedicated program, or using commercially available spreadsheet software (application program) and its macro program.

As a finite element analysis program, various known commercially available finite element analysis software for performing finite element analysis, such as Abaqus (registered trademark of Dassault Systèmes or Dassault Systèmes subsidiaries in the United States and other countries), etc. it can.
The finite element analysis program includes the following programs.
1) A program for creating a finite element model:
In the present embodiment, the program is for creating a finite element model of the golf club head 10.
2) A program for performing simulation (analysis) by the finite element method using a finite element model:
In the present embodiment, a program for performing eigenvalue analysis (vibration analysis) and collision analysis using a finite element model of a golf club head. Note that frequency response analysis may be performed instead of eigenvalue analysis.
3) Program for outputting simulation results:
It is a program for visualizing and outputting simulation results as figures and numerical tables in various forms including contour diagrams.

The disk device 40 records and / or reproduces data on a recording medium such as a CD or a DVD.
The keyboard 42 and the mouse 44 receive an operation input by the operator.
The display 46 displays and outputs data, and the printer 48 prints and outputs data. The display 46 and the printer 48 output data.
The input / output interface 50 exchanges data with an external device.

Next, the design method according to the embodiment will be described with reference to the flowchart of FIG.
The following processes are basically performed by the computer 30 executing the finite element analysis program and the calculation program. In the following description, first, the entire processing procedure of the design method is schematically described, and then each processing procedure is specifically described.

  FIG. 3 is a flowchart illustrating an outline procedure of the design method according to the embodiment. First, the computer 30 generates a finite element model that reproduces the golf club head, changes the design parameter in the finite element model, analyzes the behavior of the finite element model, and determines a predetermined characteristic value for each design parameter from the analysis result. And an optimization model having a design parameter that optimizes the characteristic value is generated (step S301: optimization model generation step).

  Next, the design parameters of the optimization model generated in step S301 are converted into pixel gradations, and image data with a predetermined number of pixels is generated (step S302: image data generation step). Subsequently, for each pixel in the image data, pixel gradation averaging processing is performed with surrounding pixels (step S303: averaging step). Then, the pixel gradation of the averaged image data is reconverted into design parameters to generate an average model (step S304: average model generation step). Finally, the rib of the golf club head is designed using the averaging model (step S305: rib design step), and the processing according to this flowchart is terminated.

  FIG. 4 is an explanatory diagram of an outline procedure of the design method according to the embodiment. FIG. 4A shows an optimization model obtained in the optimization model generation step (step S301 in FIG. 3). FIG. 4B shows an average model obtained by converting the optimization model into image data (step S302: image data generation step) and performing an averaging process (step S303: averaging step, step S304). : Averaging model generation step). FIG. 4C shows a final design model in which ribs are designed using an averaging model (step S305: rib design step). In FIG. 4C, a rib is formed at the position of the dotted line in FIG.

  Thus, in the design method according to the present embodiment, the image processing technique is applied to the optimization model using the finite element model to smooth the step in the face portion. As a result, it is possible to obtain a final design model with less irregularities on the face surface while maintaining the performance of the optimized model. In the design method according to the present embodiment, the face portion is a rib structure, and the wall thickness is reduced as compared with the optimized model. This makes it possible to obtain a final design model that is suitable for mass production and has both performance and efficiency.

  Details of the processing in each step (steps S301 to S305) in FIG. 3 will be described below.

(Optimized finite element model generation step)
FIG. 5 is a flowchart showing the processing procedure of the optimized finite element model generation step. First, design parameters to be changed in the golf club head 10 are set (step S501: condition setting step). How to set the design parameters is determined by the designer. In the present embodiment, the design parameter is the thickness value of the face portion 14.

  FIG. 6 is a diagram illustrating a state in which the face surface 12 is set by being divided into a large number of regions a. As shown in FIG. 6, the face portion 14 is set by being divided into a number of predetermined areas a, and the design parameters are set corresponding to each area. That is, in one region a, the design parameter (thickness value) is the same value. In the present embodiment, 187 regions a are set in a lattice pattern on the face surface 12. The number, shape, and area of the plurality of regions a are not limited, and can be set based on the time required for calculation and the evaluation result of the finally obtained design parameter.

  Returning to the description of FIG. 5, next, a golf club head model that reproduces the golf club head with the design parameters as variables is generated (step S502: finite element model creation step). That is, a golf club head model that is a finite element model of the golf club head 10 is created.

  The finite element model is created based on a conventionally known finite element method. Specifically, three-dimensional shape data of the golf club head 10 created using a three-dimensional CAD program, that is, design data (CAD data) is input to the computer 30. In addition, various data including constraint conditions and material constants necessary for creating a finite element model of the golf club head 10 are input to the computer 30. When the computer 30 executes the finite element analysis program, the three-dimensional shape data of the golf club head 10 is divided into meshes. As the finite element, either a shell element or a solid element may be used. However, using a shell element is advantageous in that the time required for calculation is shortened as compared with a solid element.

  The golf club head model is composed of the entire golf club head 10, more specifically, a finite element model of the golf club head 10 including all of the face portion 14, the crown portion 16, the sole portion 18, and the side portion 20. The That is, the number of elements is different between the golf club head model used in the eigenvalue analysis processing (steps S505 and S507) and the golf club head model used in the impact analysis processing (steps S506 and S508).

  Next, an allowable range of design parameter values, a first characteristic value that is a characteristic value as an evaluation target of the golf club head 10, and a second characteristic value that is a golf club characteristic value that satisfies a predetermined constraint condition. , The optimum condition to be satisfied by the first characteristic value, and the constraint condition are set (step S503: condition setting step). Note that step S503 may be executed next to step S501. How to set the allowable range of the values of the design parameters, the first characteristic value, the second characteristic value, the optimum condition, and the constraint condition is determined by the designer.

  Further, as will be described below, the computer 30 repeatedly changes the value of the design parameter within an allowable range, and sets the first and second characteristic values for the golf club head model generated by this change every time the change is made. In step S503, an upper limit number of the calculation times is set in advance. The upper limit of the number of calculations is appropriately set within a range in which the obtained design parameters are appropriate while suppressing an unnecessarily long time required for a series of calculation processes.

  In the present embodiment, the first characteristic value is a face deflection area which is an area of a region where the deflection amount on the face surface 12 is equal to or larger than a predetermined amount. A larger face deflection area is advantageous in securing a larger sweet area. The optimum condition to be satisfied by the first characteristic value is that the face deflection area is as large as possible.

The second characteristic value includes the weight Wt of the face portion 14, the CT value which is the coefficient of restitution of the face surface 12, the maximum deflection point in the primary vibration of the face surface 12, and the gravity center position of the golf club head 10. 12 is a separation distance L between the barycentric point projected perpendicularly to 12 and the maximum deflection point. The separation distance L may be the distance between the geometric center point (center point) of the face and the maximum deflection point.
The constraint condition of the second characteristic value is exemplified as follows.
Weight Wt: Wt ≦ 53g
CT value: CT ≦ 257 μsec
Separation distance L: 7.0 ≦ L ≦ 10.0 mm
The grounds for setting each constraint are as follows.
The weight Wt is appropriately set as a design condition.
This is because the upper limit of the CT value is limited to 257 μsec.
This is because the separation distance L is an advantageous range for securing a sweet area when used by a golfer who performs a standard swing as will be described later.

  Next, the computer 30 sets design parameters for each region a (step S504). The design parameter is changed and set within a predetermined allowable range. In the present embodiment, the allowable range of the wall thickness value is 1.5 to 6 mm.

  Next, the computer 30 performs in parallel three processes for calculating the first and second characteristic values for the golf club head model in which the design parameter values are set (steps S505 to S510). That is, the computer 30 executes the eigenvalue analysis to calculate the first characteristic value and the second characteristic value related to the deflection of the face surface 12 (steps S505 and S507). The first characteristic value related to the deflection of the face surface 12 is a face deflection area described later. The second characteristic value regarding the deflection of the face surface 12 is the separation distance L.

  In addition, the computer 30 calculates a second characteristic value related to head repulsion by performing impact analysis (collision analysis) between the head and the mass body (steps S506 and S508). The second characteristic value relating to the head rebound is a CT value which is a restitution coefficient.

  In addition, the computer 30 performs calculation based on the thickness value set in each region a, the area of each region, and the specific gravity of the material constituting the face portion 14, and the face portion as the second characteristic value is calculated. A weight Wt of 14 is calculated (steps S509 and S510). Such calculation is performed, for example, by the computer 30 executing spreadsheet software. In the present embodiment, steps S505 to S510 correspond to a characteristic value calculation step for calculating characteristic values using a finite element model.

  Next, the computer 30 determines whether or not the number of calculations (the number of executions of the three processes) has reached the upper limit number (step S511). If the number of calculations has not reached the upper limit number (step S511: No), the process returns to step S504, the design parameter is changed and set within a predetermined allowable range, and the same processing is repeated.

In the present embodiment, steps S504 to S511 repeatedly change the value of the design parameter given to the golf club head model within an allowable range, and perform a characteristic value calculation step for the finite element model generated by this change every time the change is made. This corresponds to the repeated step to be executed.
Note that, as a method for changing the design parameters when the processes in steps S504 to S511 are repeatedly executed, a global optimum solution search based on random sampling independent of the initial value can be used. For example, the annealing method (SA) Various conventionally known techniques of genetic algorithm (GA) can be adopted.

  If the number of calculations reaches the above upper limit number in step S511 (step S511: Yes), the computer 30 calculates the characteristic value obtained so far, that is, the face deflection area as the first characteristic value, and the first characteristic value. The weight Wt, the CT value, the maximum deflection point, and the separation distance L as the characteristic values of 2 are output (step S512).

  Then, it is determined whether or not there is a design parameter in which the first characteristic value satisfies the optimum condition and the second characteristic value satisfies the constraint condition (step S513). If the determination result is affirmative (step S513: Yes), the computer 30 selects a design parameter (optimization model) in which the first characteristic value satisfies the optimal condition and the second characteristic value satisfies the constraint condition. ) (Step S514).

  On the other hand, if the determination result in step S513 is negative (step S513: No), the computer 30 reviews the optimum conditions and constraint conditions set in step S503, changes one or both of the optimum conditions and constraint conditions, and again A similar process is executed. The processing in steps S512 and S513 is performed, for example, by the computer 30 executing spreadsheet software.

  In the present embodiment, steps S513 and S514 correspond to the optimization step of obtaining the design parameter value when the characteristic value obtained in the repetition step satisfies the optimum condition as the optimized design parameter value. In the present embodiment, since the face surface 12 is divided into 187 areas a, the wall thickness value, which is a design parameter, is also set in each area a. Therefore, a total of 187 wall thickness values can be obtained. become.

  In general, a plurality of optimization models are obtained in the optimization model generation step. Thereafter, unless otherwise specified, each step is processed for each of the obtained optimization models.

(Image data generation step)
In the image data generation step, the design parameters of the optimization model generated in the optimization model generation step are converted into pixel gradations, and image data having a predetermined number of pixels is generated. More specifically, a predetermined region (for example, 1 mm square) is set as one pixel (pixel) in the optimization model, and a design parameter (thickness value) set in each region a is converted into a pixel gradation. The size of the area corresponding to one pixel is arbitrary.

(Averaging step)
FIG. 7 is an explanatory diagram showing an outline of processing in the averaging step. In the averaging step, pixel gradation averaging processing is performed between each pixel in the image data and surrounding pixels. Specifically, when the pixel to be processed is the pixel P, an average value of the pixel gradations in the pixel group Q within the circle having the radius R with the target pixel P as the center is taken (averaging process), and this average pixel The gradation is replaced with the pixel gradation of the target pixel P. By performing this process for all the pixels in the image data, averaged image data can be obtained.

The radius R is, for example, 3 mm ≦ R ≦ 6.5 mm, preferably about 4.75 mm. This is because if the radius R is too large, the information of the pixel gradation of each part is lost too much, and if the radius R is too small, the steps cannot be averaged.
When the circle with the radius R protrudes outside the outline of the face portion as in the target pixel P ′, for example, an average value of the pixel gradations in the pixel group Q ′ in the outline is taken, and this average pixel gradation is calculated. The pixel gradation of the target pixel P ′ is replaced.

  FIG. 8 is an explanatory diagram showing image data before and after the averaging step. 8A is the original image data obtained by the image data generation step, FIG. 8B is the image data obtained by performing the averaging process with the radius R = 0.79 mm, and FIG. This is image data obtained by performing an averaging process with a radius R = 3.18 mm. Comparing FIG. 8A and FIG. 8B, it can be seen that the change rate of the pixel gradation, that is, the step in the face portion is reduced by the averaging process. Further, comparing FIG. 8B and FIG. 8C, the change rate of the pixel gradation (step difference in the face portion) increases as the radius R increases, that is, as the number of pixels to be averaged increases. You can see that it is small and gentle.

  Note that the method of determining the peripheral pixels to be subjected to the averaging process is arbitrary. That is, in FIG. 7, pixels included in a circle having a radius R are targeted for averaging processing. However, for example, pixels included in a rectangular area centered on the target pixel may be targeted for averaging processing. Good.

  In addition, various known averaging methods can be used to determine the average pixel gradation in the averaging process. For example, as described above, in addition to the average method of replacing the pixel gradation of the target pixel with the average value of the pixel gradation in the area, the intermediate value when the pixel gradation in the area is rearranged in ascending order (or descending order) For example, a median method (intermediate value method) that replaces the pixel gradation of the target pixel and a Gaussian method that averages the pixel gradation in the region by a filter based on a Gaussian function can be used.

(Averaged model generation step)
In the averaging model generation step, the pixel gradation of the averaged image data is reconverted into design parameters to generate an average model. More specifically, the pixel gradation of the averaged image data is reconverted into the thickness value of the golf club head to generate an average model.

(Rib design step)
FIG. 9 is a flowchart showing the processing procedure of the rib design step. First, when the averaged model generated in the averaged model generating step is input (step S901), an averaged model having a face deflection area size of the top 80% is extracted from a plurality of averaged models ( Step S902). The average model having the largest face deflection area of 80% is an averaging model having the face deflection area value of 100 in the averaging model having the largest face deflection area and having the face deflection area value of 80%. . In step S902, for example, the above extraction is performed with reference to the characteristic value of each model calculated in the characteristic value calculating step of FIG.

  Next, the distribution of design parameters in a plurality of averaging models, that is, the distribution of the wall thickness value is classified to determine the rib shape and position (step S903: determination step). In the golf club head design method according to the present embodiment, since the level difference smoothness is large, it is possible to easily grasp the rib arrangement information. And the finite element model which reproduces the golf club head which has the rib of the shape and position determined at Step S903 is generated (Step S904: Finite element model generation step).

  Subsequently, collision analysis is performed using the finite element model generated in step S904, a characteristic value is calculated (step S905: characteristic value calculation step), and a result of the characteristic value is output (step S906). The characteristic values calculated at this time are the CT value and the coefficient of restitution (COR value). Here, the coefficient of restitution means U.S. S. G. A (American Golf Association) COR measurement method (Procedure for Measuring the Velocity Ratio of a Club Head for Conformance to Rule 4-1e, Revision 2 (February 8, 1999). Since is in a positive correlation, for example, the coefficient of restitution can be converted from the amount of deflection.

  When the output characteristic value satisfies the optimum condition (step S907: Yes), the computer 30 outputs a design parameter whose characteristic value satisfies the optimum condition as a final design model (step S908). On the other hand, when the output characteristic value does not satisfy the optimum condition (step S907: No), the computer 30 reviews the shape and position of the rib determined in step S903, and changes one or both of the shape and position. The same process is executed again. The processing in steps S907 and 908 is performed, for example, by the computer 30 executing spreadsheet software.

In the present embodiment, steps S903 to 907 repeatedly change the design parameter value in the finite element model within an allowable range, and execute the characteristic value calculation step for the finite element model generated by this change every time the change is made. Corresponds to repeated steps. Further, in the present embodiment, steps S907 and S908 correspond to the optimization step of obtaining the design parameter value when the characteristic value obtained by the repetition step satisfies the optimum condition as the optimized design parameter value. .
By using the final design model obtained by the above processing, a golf club head having both performance and production efficiency can be obtained.

  FIG. 10 is a graph showing a comparative example of the face deflection area of the golf club head obtained by the design method according to the present embodiment. FIG. 10 shows a face deflection area (example) of a golf club head designed by using the design method according to the present embodiment, a rib according to a method according to the prior art, that is, an optimization calculation result by a finite element model. 2 shows the face deflection area of the golf club head (Comparative Example 1) and the face deflection area (Comparative Example 2) of the golf club head having a uniform thickness without performing the optimization calculation.

A golf club head designed using the design method according to the present embodiment has a face deflection area (Example) of 171 mm ² , Comparative Example 1 of 159 mm ² , and Comparative Example 2 of 132 mm ² . According to the design method of the present embodiment, the face deflection area can be made larger than any of the comparative examples.

As described above, according to the golf club head design method according to the embodiment, the optimization model obtained by the optimization process is converted into image data and the averaging process is performed. The position and shape of the rib are determined after reducing the degree of unevenness. Thereby, design data suitable for mass production can be obtained while improving the performance by the optimization process.
In addition, according to the golf club head design method according to the embodiment, practical design data can be obtained efficiently, and the mass production of golf club heads can be handled smoothly.

  Further, as shown in FIG. 10, the golf club head designed by the golf club head designing method according to the embodiment has a larger deflection area than the golf club head designed by the method according to the prior art. A golf club head advantageous in increasing the distance can be realized.

  DESCRIPTION OF SYMBOLS 10 ... Golf club head, 12 ... Face surface, 14 ... Face part, 30 ... Computer, P, P '... Target pixel, Q, Q' ... Pixel group, R ... Radius, a ... region.

Claims (10)

Generate a finite element model that reproduces the golf club head, analyze the behavior of the finite element model by changing the design parameter in the finite element model, calculate a predetermined characteristic value for each design parameter from the analysis result, An optimization model generation step of generating an optimization model having the design parameters such that the characteristic value is optimal;
An image data generation step of converting the design parameters of the optimization model into pixel gradations and generating image data of a predetermined number of pixels;
In each pixel in the image data, an averaging step for averaging pixel gradations with surrounding pixels;
An averaged finite element model generating step of reconverting the pixel gradation of the averaged image data into the design parameter to generate an averaged model;
A rib design step of designing a rib of the golf club head using the averaged model;
A method of designing a golf club head, comprising: The optimization model generation step includes:
A condition setting step for setting an allowable range of the design parameter and an optimum condition of the characteristic value;
A finite element model generating step for generating the finite element model for reproducing the golf club head with the design parameter as a variable;
A characteristic value calculating step of calculating the characteristic value using the finite element model;
Repetitively changing the value of the design parameter in the finite element model within the allowable range, and executing the characteristic value calculating step for the finite element model generated by the change every time the change is made;
An optimization step for obtaining the value of the design parameter as the value of the optimized design parameter when the characteristic value calculated in the repetition step satisfies the optimal condition;
The golf club head design method according to claim 1, comprising:   3. The golf club head according to claim 1, wherein in the optimization model generation step, the characteristic value is calculated by performing at least one of eigenvalue analysis or collision analysis using the finite element model. Design method.   The characteristic value includes a face deflection area which is an area of a region where the deflection amount on the face surface of the golf head is a predetermined amount or more, a maximum deflection point in primary vibration of the face surface, and a gravity center position of the golf head. It includes at least one of a separation distance between a center of gravity point projected perpendicularly to the face surface and the maximum deflection point, a coefficient of restitution of the golf head, and a weight of the golf head. The method for designing a golf club head according to claim 1. The rib design step includes:
A determining step for determining the shape and position of the rib based on the distribution of the design parameters in the averaging model;
A finite element model generating step for generating a finite element model that reproduces the golf club head having ribs of the shape and position;
A characteristic value calculating step of calculating the characteristic value using the finite element model;
Repetitively changing the value of the design parameter in the finite element model within the allowable range, and executing the characteristic value calculating step for the finite element model generated by the change every time the change is made;
An optimization step for obtaining the value of the design parameter as the value of the optimized design parameter when the characteristic value calculated in the repetition step satisfies the optimal condition;
The golf club head design method according to claim 1, further comprising: In the optimization model generation step, a plurality of the optimization models are generated,
In the image data generation step, a plurality of the image data respectively corresponding to the plurality of optimization models are generated,
In the averaging step, an averaging process is performed for each of the plurality of image data,
In the averaged finite element model generation step, a plurality of the averaged models respectively corresponding to the plurality of the averaged image data are generated,
In the rib designing step, the rib of the golf club head is designed by using only the averaging model having the largest 80% of the face deflection area among the plurality of averaging models. Item 6. A golf club head design method according to any one of Items 1 to 5.   In the averaging step, in each pixel in the image data, an average value of the pixel gradations of pixels within a circle having a radius R centering on the target pixel is set as the pixel gradation of the target pixel. A method for designing a golf club head according to any one of claims 1 to 6.   The golf club head design method according to claim 7, wherein the radius R is 3 mm ≦ R ≦ 6.5 mm.   9. The golf club head design method according to claim 1, wherein the design parameter is a thickness value of a face portion of the golf head.   A golf head designed using the golf club head design method according to claim 1.

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