Method and program for calculating magnetic attraction force

Abstract

To calculate the magnetic attraction force on a mold in a short time using a magnetic clamping device. [Means for solving the problem] The spreadsheet data is generated by dividing the magnetic clamping surface of the magnetic clamping device 10 into a matrix of unit regions, with each unit region identified as a single cell by matrix coordinates. A predetermined numerical value other than "0" is set in the cell corresponding to the position of the magnetic pad, while other cells are either filled with "0" or left blank. The matrix coordinate calculation unit 120 calculates the matrix coordinates of the cells corresponding to the diagonal vertices of the mold 2a when the representative position of the mold 2a is positioned at the representative position on the platen 3 side. The spreadsheet calculation unit 130 sums the numerical values ​​entered in the cells within the range enclosed by the rectangle specified by the calculated matrix coordinates.

Description

Technical Field

[0001] The present invention relates to a method for calculating magnetic adsorption force when attaching a mold to a magnetic clamp device and a calculation program therefor.

Background Art

[0002] As a device for attaching a mold to an injection molding machine, a magnetic clamp device that utilizes magnetic adsorption force is known. For example, the magnetic clamp device disclosed in Patent Document 1 has a plate body made of a magnetic material attached to a platen of an injection molding machine, and fixes the mold by magnetic adsorption force. A plurality of magnetic pads are provided on the plate body. Each magnetic pad has a magnet (for example, a neodymium magnet) with non-invertible polarity provided around a magnetic pole and a magnet (for example, an alnico magnet) with invertible polarity arranged on the back side of the magnetic pole. By controlling the magnetic polarity of the alnico magnet with a coil, it is possible to switch between a magnetic circuit that closes within the plate body and a magnetic circuit that passes through the mold.

[0003] As a method for positioning a mold at a predetermined position on a platen, a locater ring method, a positioning block method, etc. are used. In the positioning method using the locater ring method, a protrusion called a locater ring is provided near the center of the back of the mold, and the locater ring is inserted into a hole provided in the fixed-side platen, thereby positioning the attachment to the fixed-side platen. Also, in the positioning block method, a tapered positioning protrusion engages with a positioning notch on the mold side and a positioning protrusion on the platen side so as to follow the tapered shape due to the weight of the mold, eliminating lateral displacement. When the mounting surface on the mold side contacts the mold receiving surface, the positioning in the height direction is completed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] The back surface of a mold that is held in place by a magnetic clamping device is generally rectangular, but its length and width vary depending on the mold. On the other hand, on the suction surface of the magnetic clamping device, magnetic pads are discretely arranged, and not all magnetic pads necessarily come into contact with the back surface of the mold. Some contact, some do not, and some only make partial contact.

[0006] While the magnetic attraction force on a particular mold can be measured when it is actually attached to a magnetic clamping device, it is also necessary to predict in advance how much magnetic attraction force will be exerted. If the measured value is significantly lower than the predicted value, the surface condition of the back of the mold can be inspected and examined.

[0007] One method for predicting magnetic attraction force is to determine the contact area between the back of the mold and the magnetic pad, and then multiply this area by the magnetic attraction force per unit area. This method is only an approximation because it does not take into account the magnetic flux that wraps around the magnetic pad from space, but it is a useful method for simply determining magnetic attraction force.

[0008] However, when determining the area in contact between the back of the mold and the magnetic pad, complex area calculations, such as calculating the area of ​​a sector using trigonometric functions, are essential in areas where the magnetic pad is circular or elliptical and partially overlaps with the back of the mold. In the processing unit of the magnetic clamping device, this calculation process can take several seconds to tens of seconds, causing user dissatisfaction with the responsiveness.

[0009] To solve these problems, the object of the present invention is to provide a magnetic attraction force calculation method and a calculation program that can calculate the magnetic attraction force to a mold in a short amount of time. [Means for solving the problem]

[0010] To achieve the above objective, the present invention provides a method for calculating the magnetic attraction force when a rectangular mold is attached to a platen equipped with a magnetic clamp device, The magnetic clamping surface of the magnetic clamping device is divided into unit regions in a matrix, and each unit region is identified as a single cell by matrix coordinates, and the table data holds such that a predetermined numerical value other than "0" is set in the cell corresponding to the magnetic pad, and "0" is entered or the cell is left blank. The matrix coordinates corresponding to the representative position of the aforementioned table data are stored as representative matrix coordinates. When the representative position of the mold is positioned at the representative position on the platen side, the matrix coordinates of the cells corresponding to the vertices at the diagonal positions of the mold are obtained from the representative matrix coordinates. The magnetic attraction force is calculated by summing the values ​​entered in the cells within the range specified by the matrix coordinates obtained above.

[0011] Furthermore, the magnetic adsorption force calculation program of the present invention is a calculation program for calculating the magnetic adsorption force when a rectangular mold is attached to a platen equipped with a magnetic clamp device, The magnetic clamping surface of the magnetic clamping device is divided into unit regions in a matrix, and each unit region is identified as a single cell by matrix coordinates, and the table data holds such that a predetermined numerical value other than "0" is set in the cell corresponding to the magnetic pad, and "0" is entered or the cell is left blank. The matrix coordinates corresponding to the representative position of the aforementioned table data are stored as representative matrix coordinates. A matrix coordinate calculation unit that determines the matrix coordinates of cells corresponding to vertices at diagonal positions of the mold when the representative position of the mold is positioned at the representative position on the platen side, The system is characterized by having a spreadsheet unit that sums the numerical values ​​entered in the cells within the range specified by the matrix coordinates obtained above. [Effects of the Invention]

[0012] According to the present invention, the magnetic clamping surface of the magnetic clamp device is divided into unit regions, and each unit region is represented as a single cell in the table data. A predetermined value other than "0" is set in the cell corresponding to the magnetic pad, and "0" (or null) is set in the other cells. The numerical values ​​entered in the cells within the range enclosed by the rectangle specified by the matrix coordinates at the diagonal positions are summed up, and the magnetic attraction force can be calculated based on this value. Since this calculation does not require complex area calculations, the magnetic attraction force can be determined in a short time even with a processing device with low computing power. [Brief explanation of the drawing]

[0013] [Figure 1] This diagram shows how to set up a mold in an injection molding machine. Figure 1A shows the injection molding machine and the mold, and Figure 1B shows the suspended mold. [Figure 2] This diagram shows a magnetic clamping device attached to the fixed platen. [Figure 3] This diagram illustrates an example of magnetic pad data set in a processing device. Figure 3A shows an example magnetic clamping device, and Figure 3B shows the magnetic pad data. [Figure 4] This is a diagram showing the schematic configuration of the processing unit. [Figure 5] These are diagrams illustrating the process; Figure 5A shows the mold, and Figure 5B shows the mold schematically overlaid on the tabular data. [Figure 6] This is a diagram showing the surface of the mold that is to be adsorbed. [Figure 7] This is a diagram showing the mold-side worksheet. [Modes for carrying out the invention]

[0014] [Example 1] Figure 1 shows the state of setting the mold 2 in the injection molding machine 1. In Figure 1A, the injection molding machine 1 has a fixed platen 3 and a movable platen 4. The movable platen 4 is guided by a bar 5 and can move relative to the fixed platen 3. Magnetic clamping devices 10 and 20 are mounted on the fixed platen 3 and the movable platen 4 respectively. The magnetic clamping devices 10 and 20 are controlled by a processing device 30. The processing device 30 exchanges necessary information with the injection molding machine 1. The processing device 30 is a computer installed with control software and spreadsheet software in addition to other software.

[0015] In the drawing, on the right side of the fixed platen 3, an injection unit 7 having a hopper 6 for inserting raw materials is arranged, and an injection nozzle 8 is attached to the injection unit 7. The injection nozzle 8 injects raw materials into the mold 2 through a hole opened in the fixed platen 3.

[0016] Figure 1B shows the suspended mold 2. The mold 2 is suspended in a state where the fixed mold 2a and the movable mold 2b face each other. Suspension rings 9a and 9b are provided at one location on the diagonal line of the fixed mold 2a and the movable mold 2b respectively. In this embodiment, it is assumed that a positioning method by the locator ring method is applied, and a locator ring 2c is attached to the center position of the back surface of the mold 2a.

[0017] Figure 2 shows the adsorption surface of the magnetic clamping device 10 mounted on the fixed platen 3 side. Hereinafter, the magnetic clamping device 10 will be described.

[0018] The magnetic clamping surface of the magnetic clamping device 10 exposes the circular pad surfaces of multiple magnetic pads 11 and the surrounding surface of the plate body 13. The plate body 13 is made of a magnetic material. The magnetic clamping surface of the magnetic clamping device 10 is provided with a reference hole 12 into which the locating ring 2c is pressed. The reference hole 12 communicates with a hole on the fixed-side platen 3 through which the injection nozzle 8 passes toward the mold 2a (if the magnetic clamping device 10 is not attached to the fixed-side platen 3, the locating ring 2c is pressed into this hole).

[0019] Next, a method for calculating the magnetic attraction force when attaching the mold 2a to the magnetic clamping device 10, and a program for calculating that force, will be described. In this invention, spreadsheet software is used. As an example of spreadsheet software, Microsoft's Excel® spreadsheet software is well known. The spreadsheet software used in this embodiment is not limited to Microsoft's spreadsheet software, but since its human interface is well known, for the sake of explanation, the notation of that human interface will be used in the description.

[0020] According to the company's spreadsheet software, table data is represented in row / column format, with row identifiers A, B, etc. in the first row and column identifiers 1, 2, etc. in the leftmost column. For each cell in the table data, the matrix coordinates can be specified by a combination of row and column identifiers, such as "A3" or "E5". The software also provides a SUM function that sums the numbers entered in a selected range. The SUM function can be written as "=SUM(A1:A100)" or "=SUM(A1,A2...)". When written as "=SUM(A1:A100)", a rectangle is specified with matrix coordinates A1 and A100 as diagonal positions, and the numbers entered in the cells within this rectangle are summed.

[0021] Figure 3 illustrates an example of tabular data held in the processing unit 30. The magnetic clamp device 10 in the example (Figure 3A) has a rectangular surface with an outer shape of 1m x 1m, with four magnetic pads 11 arranged therein, and a reference hole 12 into which a locating ring is pressed is provided at the center (500mm x 500mm). Note that the magnetic clamp device's surface in reality is not necessarily a perfect rectangle, but it is sufficient to virtually imagine a rectangle that encloses all the molds to which it is intended to be attached. The tabular data corresponding to the magnetic clamp device 10's surface can be represented as 1000 rows x 1000 columns of tabular data (see Figure 3B). In this tabular data, the magnetic clamp device 10 is divided into 1mm x 1mm unit areas in a matrix, and each unit area corresponds to one cell and is identified by matrix coordinates. The matrix coordinates of the cell corresponding to the upper left unit area of ​​the magnetic clamping surface 10 are A1 (position: 0 mm vertical, 0 mm horizontal), and the matrix coordinates of the cell corresponding to the lower right unit area are ALL1000 (position: 1000 mm vertical, 1000 mm horizontal).

[0022] The position of the reference hole 12 into which the locating ring 2c is pressed is defined as the representative position on the fixed platen 3 side, and the representative matrix coordinates of the cell corresponding to this representative position are set to SF500 (central matrix coordinates, 500mm vertically, 500mm horizontally). On the other hand, the representative position on the mold 2a side is the position of the locating ring 2c.

[0023] In this type of tabular data, the cell corresponding to the coordinate position of the magnetic pad 11 is filled with the number "1", while all other cells are filled with the number "0" or left blank "null". In the diagram, only "1" is entered to avoid complexity.

[0024] Figure 4 shows the schematic configuration of the processing unit 30. The processing unit 30 receives mold data as input. For the sake of explanation, the mold is assumed to have a vertical length (=500 mm) and a horizontal length (=500 mm), as shown in Figure 5A, and the position of the locating ring 2c is set to the center position where the diagonals intersect.

[0025] The matrix coordinate calculation unit 120 calculates the matrix coordinates (IP250, ADV750) of the cells corresponding to the vertices of the upper left corner and lower right corner (vertices at diagonal positions) of the mold 2a, based on the input mold data, when the central position of the locating ring 2c is aligned with the cell of the representative matrix coordinate SF500 of the position of the reference hole 12. The calculations required for this calculation are simple arithmetic operations.

[0026] Figure 5B schematically shows the mold 2a shown in Figure 5A overlaid on the table data. Mold 2a is indicated by a dashed line. The spreadsheet unit 130 calculates the sum of the cells entered in the range enclosed by the matrix coordinates at the obtained diagonal positions (see Figure 5B) (=SUM(IP250:ADV750)). Since each cell corresponding to the magnetic pad 11 is entered as "1", the sum is a value corresponding to the overlapping area of ​​the magnetic pad 11 and mold 2a.

[0027] The magnetic attraction force conversion unit 140 converts the obtained total into magnetic attraction force. If the magnetic attraction force per unit area is defined, the total magnetic attraction force can be obtained by multiplication. Alternatively, the magnetic attraction force values ​​corresponding to the obtained total can be stored in memory as a correspondence table in advance, and the corresponding magnetic attraction force can be retrieved based on the total result and displayed on the display of the processing unit 30. Since it only involves retrieving data, the result can be obtained slightly faster than calculation. The degree of approximation of the obtained magnetic attraction force changes depending on the size of the unit area, but the accuracy of the outer shape of the mold 2a is not very high, and a sufficiently reliable value can be obtained even with 1 mm x 1 mm.

[0028] In this embodiment, "1" was set for each cell at the coordinate position corresponding to the magnetic pad 11, and "0" (or null) was set for the other cells. However, other predetermined numerical values ​​other than "0" may be set for each cell at the coordinate position corresponding to the magnetic pad 11. For example, the value of the magnetic attraction force per unit may be set. In that case, processing by the magnetic attraction force conversion unit 140 is unnecessary. Also, in this case, the value of the magnetic attraction force per unit at the periphery of the magnetic pad 11 and the value of the magnetic attraction force per unit at the center of the magnetic pad 11 do not have to be the same. This makes it possible to handle cases where it is known that there are differences in magnetic flux density depending on the location.

[0029] In this embodiment, the magnetic clamping surface of the magnetic clamping device 10 is divided into unit regions, and each unit region is represented as a single cell in the table data. A predetermined value other than "0" is set in the cell corresponding to the magnetic pad 11, and "0" (or null) is set in the other cells. The numerical values ​​entered in the cells within the range enclosed by the rectangle specified by the matrix coordinates at the diagonal positions are summed up, and the magnetic attraction force can be calculated based on this value. Since this calculation does not require complex area calculations, the magnetic attraction force can be determined in a short time even with a processing device 30 that has low computing power.

[0030] [Example 2] Depending on the mold owned by the customer, there may be irregularities in the outer shape and defects such as holes on the surface of the mold to be attached. If these defects coincide with the position of the magnetic pad 11, errors will occur in the method of Example 1. Example 2, described below, is effective when the outer shape of the mold is irregular (for example, the area 41 shown by the dashed line) and cannot be considered rectangular, or when there are defects such as holes (for example, the area 42) on the surface of the mold to be attached (hereinafter collectively referred to as "defects").

[0031] In Example 1, when the representative position of the mold is positioned at the representative position on the platen side, the matrix coordinates of the cells corresponding to the vertices at the diagonal positions of the mold are obtained from the representative matrix coordinates. In Example 2, the numerical values ​​entered in the cells within the range specified by the obtained matrix coordinates were summed, but in Example 2, other functions of the spreadsheet software are used.

[0032] In Example 2, the table data created in Example 1 is referred to as the clamp-side table. Furthermore, for the mold 10 side, the surface to be attracted is divided into unit areas of the same size as the platen side, and a mold-side table is prepared in which each unit area is represented as a single cell. Then, numerical values, characters, or formatting are assigned to the cells corresponding to missing data in the mold-side table, and the magnetic attraction force is determined by performing a predetermined process using the clamp-side table and the mold-side table. For the sake of explanation, the following explanation will use the worksheet function of spreadsheet software, with the mold-side table and clamp-side table provided in separate worksheets. It goes without saying that the mold-side table and clamp-side table may also be calculated in separate areas within the same worksheet.

[0033] In Example 2, there are several forms of predetermined processing for the clamp-side worksheet and the mold-side worksheet, each of which will be explained using Figure 7. Note that the clamp-side worksheet 44 is the same as the table data in Example 1, so its explanation will be omitted. In the following example, the mold-side worksheet 45 is arranged so that the center position of the locating ring 2c and the position of the reference hole 12 overlap on the clamp-side worksheet 44. The mold-side worktable and the clamp-side worktable do not need to be the same size as long as there is a corresponding relationship between each cell. In the mold-side worksheet 45, cells corresponding to areas where there is no metal to be attracted are marked with "*". If the mold-side worktable and the clamp-side worktable are the same size on the worksheet, "*" will be entered over a wide area 43 of the outer shape of the mold 10 on the mold-side worksheet 45. Cells corresponding to areas with metal or the locating ring 2c are marked with "0" or null. In addition, a results worksheet 46 is prepared as needed to obtain the results during the calculation. A predetermined numerical value other than "0" is set in the cell corresponding to the magnetic pad, which in this case will be x (numerical data).

[0034] [Example 2-1] Form for inserting numerical values ​​into cells In this configuration, "-x" is entered in the "*" cell of the mold-side worksheet 45 in Figure 7.

[0035] The information from the same cell positions in the mold-side worksheet 45 and the clamp-side worksheet 44 is added together. This can be calculated by adding (or subtracting x) the mold hole portion -x from the magnetic pole portion 1. Then, the result is output to the result worksheet 46, displaying "0" if the result is 0 or less. More specifically, this calculation is performed by setting "=IF(cell position in mold-side worksheet + cell position in clamp-side worksheet)<=x, 0, "", "cell position in mold-side worksheet + cell position in clamp-side worksheet)" in each cell of the result worksheet 46, so that if the added value is 0 or less, "0" is displayed, and otherwise the original value is displayed. Alternatively, it can be displayed as null. In this case, set "=IF(cell position in mold-side worksheet + cell position in clamp-side worksheet)<=x, "", "", "cell position in mold-side worksheet + cell position in clamp-side worksheet)" in each cell of the result worksheet.

[0036] The magnetic attraction force can be determined by calculating the sum in the results worksheet 46 either within the range of the mold 10 (a rectangular area specified by the matrix coordinates of cells corresponding to the diagonal vertices of the mold 10, similar to Example 1), or over the entire results worksheet 46.

[0037] [Example 2-2] Form for inserting text into a cell In this configuration, the difference from Example 2, 1 is that a "string" (for example, "a") is entered in the "*" cell of the mold-side worksheet 45 in Figure 7.

[0038] When a string (for example, "a") is added to a number, spreadsheet software cannot perform the calculation and returns an error value (#VALUE!). This can be used to generate an error, and based on the result, the cell can be made to appear as "0". For example, you can set "=IFERROR(cell position in mold-side worksheet + cell position in clamp-side worksheet), 0)" in a cell in result worksheet 46. By calculating the sum in result worksheet 46 for the range of mold 10, or for the entire range, you can find the magnetic attraction force. "=IFERROR(cell position in mold-side worksheet + cell position in clamp-side worksheet), ")" can also be used.

[0039] [Example 2-3] Form utilizing multiplication In this configuration, the cells marked with "*" in the mold-side worksheet 45 in Figure 7 are filled with "0". All other cells are filled with "1". This method utilizes the fact that multiplying a cell's value by "0" always results in "0". More specifically, this calculation is performed by setting "=cell position in mold-side worksheet * cell position in clamp-side worksheet" in each cell of the results worksheet 46. The magnetic attraction force can be calculated by summing the values ​​in the results worksheet for the range of mold 10, or for the mold as a whole.

[0040] [Example 2-4] Form using cell formatting (data validation) In this configuration, only text can be entered into the "*" cells in the mold-side worksheet 45 in Figure 7 (i.e., numbers cannot be entered), and all other cells are filled with "0" or null. As a result, the corresponding cells in worksheet 46 are set to (=cell position in clamp-side worksheet + cell position in mold-side worksheet).

[0041] In this way, in the resulting worksheet 46, cells corresponding to "*" will display the formula as is, and will not be displayed as numbers. When calculating the total for the entire worksheet or for the range of mold 10, cells that are recognized as text will be excluded from the calculation.

[0042] [Example 2-5] Form for inserting numerical values ​​into cells In this configuration, the "*" cell in the mold-side worksheet 45 in Figure 7 is entered with "1" or a larger number from the clamp-side worksheet. All other cells are entered with "0" or null.

[0043] The cells in the clamp-side worksheet 44 and the corresponding cells in the mold-side worksheet 45 are added together. When the position of the cell corresponding to the magnetic pad 11 is added to the cell in the area of ​​the mold 10 where there is no metal to be attracted, the result will be a value greater than 1. Using this, an IF function is used to set all numbers greater than 1 to 0.

[0044] Specifically, set the formula "=IF(cell position in mold-side worksheet + cell position in clamp-side worksheet)>x, 0, (cell position in mold-side worksheet + cell position in clamp-side worksheet)" in each cell of the results worksheet 46. Alternatively, set the formula "=IF(cell position in mold-side worksheet + cell position in clamp-side worksheet)>=x, "", (cell position in mold-side worksheet + cell position in clamp-side worksheet)". The magnetic attraction force can be calculated by summing the values ​​within the range of mold 10 in the results worksheet 46, or for the entire worksheet.

[0045] In the above embodiment, the locating ring 2c was located at the center of the mold 2a. However, if it is not at the center, the processing device 30 needs to obtain the positional relationship between the representative position on the mold side and the diagonal vertex positions of the mold from the injection molding machine 1 or other input means.

[0046] In the above embodiment, the position of the reference hole 12 into which the locating ring 2c is pressed was used as the representative position of the fixed platen 3. However, if there is another position that can be used for positioning the mold 2a and the suction surface of the magnetic clamping device 10, that position may be used. In the case of the positioning block method, the position of the positioning projection and the position of the mold receiving surface may be used as the representative position on the fixed platen side. In this case, the representative position on the mold side is the position of the positioning notch and the mounting surface on the mold side, and it is necessary to obtain the positional relationship between the representative position on the mold side and the diagonal vertex positions of the mold. By doing so, it is possible to determine the matrix coordinates of the cells corresponding to the diagonal vertices of the mold when the mold is correctly mounted on the positioning projection and the mold receiving surface. [Explanation of symbols]

[0047] 1 injection molding machine 2, 2a, 2b molds 2c Locating Ring 3 Fixed-side platen 4. Movable platen 5 bars 6 Hoppers 7. Injection Unit 8. Injection nozzle 9a, 9b rings 10, 20 Magnetic clamping devices 11 Magnetic Pads 12 Reference hole 13 Plate body 20 Magnetic clamp device 30 Processing Unit 44. Clamp-side worksheet 45 Mold-side worksheet 46 Results Worksheet 120 Matrix coordinate calculation section 130 Spreadsheet section 140 Magnetic adsorption force conversion section

Claims

1. In a calculation method for determining the magnetic attraction force when a rectangular mold is attached to a platen equipped with a magnetic clamping device, The magnetic clamping surface of the magnetic clamping device is divided into a matrix of unit regions, and each unit region is identified as a single cell by matrix coordinates, and the table data holds such that a predetermined numerical value other than "0" is set in the cell corresponding to the magnetic pad, and "0" is entered or the cell is left blank. The matrix coordinates corresponding to the representative position of the aforementioned table data are stored as representative matrix coordinates. When the representative position of the mold is positioned at the representative position on the platen side, the matrix coordinates of the cells corresponding to the vertices at the diagonal positions of the mold are obtained from the representative matrix coordinates. A calculation method for calculating magnetic attraction force by summing the numerical values ​​entered in the cells within the range specified by the matrix coordinates obtained above.

2. In a calculation program for calculating the magnetic attraction force when attaching a rectangular mold to a platen equipped with a magnetic clamping device, The magnetic clamping surface of the magnetic clamping device is divided into unit regions in a matrix, and each unit region is identified as a single cell by matrix coordinates, and the table data is held in which a predetermined numerical value other than "0" is set in the cell corresponding to the magnetic pad, and "0" is entered or the cell is left blank. The matrix coordinates corresponding to the representative position of the aforementioned table data are stored as representative matrix coordinates. A matrix coordinate calculation unit that determines the matrix coordinates of cells corresponding to vertices at diagonal positions of the mold when the representative position of the mold is positioned at the representative position on the platen side, A calculation program for calculating magnetic attraction force, characterized by having a spreadsheet unit that sums the numerical values ​​entered in cells within the range specified by the matrix coordinates obtained above.

3. In a calculation method for determining the magnetic attraction force when a rectangular mold is attached to a platen equipped with a magnetic clamping device, The magnetic clamping device has a clamp-side table in which the suction surface is divided into unit regions in a matrix, and each unit region is identified as a single cell by matrix coordinates, and a predetermined numerical value x other than "0" is set in the cell corresponding to the magnetic pad, and "0" is entered or the cell is left blank. The mold-side table is maintained in which the surface of the mold to be adsorbed is divided into unit regions in a matrix, and each unit region is identified as a single cell by matrix coordinates, wherein a predetermined numerical value, character, or format is set in the cell corresponding to the missing position, and "0" is entered or the cell is left blank. With the representative position of the clamp-side table and the representative position of the mold-side table aligned, A predetermined process is performed on the data entered in each cell of the clamp-side table and the mold-side table. A calculation method for calculating magnetic attraction force by summing the numerical values ​​of the processing results entered in each of the aforementioned cells.

4. In the calculation method of claim 3, The cell corresponding to the defect in the mold-side table is filled with the value -X. The calculation method is characterized in that the predetermined process is the sum of the data in the corresponding cells of the clamp-side table and the mold-side table, respectively.

5. In the calculation method of claim 3, A number of 1 or more is entered in the cell corresponding to the missing part of the mold-side table. The predetermined process is the sum of the data in the corresponding cells of the clamp-side table and the mold-side table, and is added to the predetermined numerical value. A calculation method characterized by treating cells that have a value greater than the predetermined value as "0" or null when performing the sum.

6. In the calculation method of claim 3, A string is entered into the cell at the position corresponding to the missing part of the mold-side table. The predetermined process involves adding the data in the corresponding cells of the clamp-side table and the mold-side table, respectively, and causing an error by adding a numerical value and a string. A calculation method characterized by treating the cells where the error occurred as "0" or null when performing the sum.

7. In the calculation method of claim 3, The cells in the mold-side table corresponding to the missing data are formatted to treat the entered data as a string. The predetermined process involves adding the data in the corresponding cells of the clamp-side table and the mold-side table, respectively, and causing an error by adding a numerical value and a string. A calculation method characterized by treating the cells where the error occurred as "0" or null when performing the sum.

Images