Method for measuring maximum depth of electric discharge continuous etching pit

Abstract

To disclose a method for measuring a maximum depth of an electric discharge continuous etching pit.SOLUTION: Single shot etching test processing for a work-piece is performed when a discharge liquid does not contain mixed powder and the work-piece is stationary, whereby a maximum depth of an etching pit is derived when the discharge liquid does not contain mixed powder and the work-piece moves. Next, single shot etching test processing for the work-piece is performed when a discharge liquid does not contain mixed powder and the work-piece is stationary, whereby the maximum depth of a single etching pit is derived, and then, maximum depths of the remaining etching pits other than the first one in a plurality of continuous etching pits when the discharge liquid does not contain mixed powder and the work-piece moves. Therefore, basis of data concerning a surface roughness of the work-piece, when single shot pulse etching processing is continuously performed with different discharge voltages, different currents, different discharge times or different work-piece materials, is provided.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention belongs to the field of electrical discharge machining, and specifically relates to a method for measuring the maximum depth of continuous electrical discharge etching pits.

Background Art

[0002] Electrical discharge machining technology is widely applied to the machining of molds and parts, and surface roughness is a main process index of electrical discharge machining technology. The surface roughness of the electrical discharge machining surface mainly depends on the maximum depth of the etching pits formed by electrical discharge machining, and the magnitude of the surface roughness value of the electrical discharge machining surface can be regarded as being in a proportional relationship with the maximum depth of the etching pits. However, any change in parameters (such as discharge voltage, discharge current, discharge time, presence or absence of mixed powder in the discharge liquid, mixed powder volume ratio, etc.) has a very significant impact on the maximum depth of the etching pits. At the same time, currently, there is almost no method for measuring the maximum depth of etching pits by single-pulse etching machining, especially there is almost no method for measuring the maximum depth of continuous etching pits when single-pulse etching machining is continuously performed. Therefore, there is a need for a method for measuring the maximum depth of continuous etching pits when single-pulse etching machining is continuously performed. By obtaining this measurement method, it is useful for calculating the surface roughness of the subsequent electrical discharge machining surface, and by combining with related parameters, it is useful for calculating the surface roughness of the electrical discharge machining surface with different related parameters.

Summary of the Invention

[0003] The object of the present invention is to provide a method for measuring the maximum depth of continuous electrical discharge etching pits in order to overcome the deficiencies of the prior art.

[0004] To achieve the above object, the present invention adopts the following technical solutions. The method for measuring the maximum depth of continuous electrical discharge etching pits of the present invention includes the following steps 1 to 5.

[0005] Step 1: Set the discharge time, discharge voltage, and discharge current of single-pulse etching test machining.

[0006] Step 2: When the mixed powder is not included in the discharge liquid and the workpiece is stationary, perform a single-pulse etching test process on the workpiece once to obtain a single etching pit when the workpiece is stationary. The etching pit when the workpiece is stationary is spherical-crowned. Measure the radius a1 of the arc at the topmost part and the maximum depth h1 of the single etching pit when the workpiece is stationary, and calculate the volume V1 of the single etching pit when the workpiece is stationary from the measured values. Subsequently, the dissipated energy W of a single pulse when the mixed powder is not included in the discharge liquid loss is calculated by the following formula. W loss =UIt - V1g In the formula, U is the discharge voltage, I is the discharge current, t is the discharge time, and g is the latent heat of phase change of the workpiece material.

[0007] Step 3: When the mixed powder is not included in the discharge liquid and the workpiece moves parallel at a preset speed, perform a single-pulse etching test process on the workpiece once to obtain a single etching pit when the workpiece moves. The etching pit when the workpiece moves is a shape combined with half of a spherical crown and a semi-elliptical cone with a semi-ellipse that is the central cross-section of the spherical crown as the bottom surface. Under the same environmental conditions, the volume V' of the single etching pit when the workpiece moves is equal to the volume V1 of the single etching pit when the workpiece is stationary. Under the same environmental conditions, the relationship between the radius a' of the arc at the topmost part and the maximum depth h' of the single etching pit when the workpiece moves is the same as the relationship between the radius a1 of the arc at the topmost part and the maximum depth h1 of the single etching pit when the workpiece is stationary, and is uniformly expressed by the following relational formula. a = εh In the formula, a and h are the radius of the arc at the topmost part and the maximum depth of the etching pit, and ε is a coefficient. Calculate the value of the coefficient ε from the measured radius a1 of the arc at the top of the etching pit and the maximum depth h1 when the workpiece is stationary, obtain the relational expression between the radius a’ of the arc at the top of a single etching pit and the maximum depth h’ when the workpiece moves, and calculate the maximum depth h’ of a single etching pit when the workpiece moves according to this relational expression, the value of the volume V1 of the etching pit, and the expression representing the volume V’ of a single etching pit when the workpiece moves.

[0008] Step 4: Prepare n types (n ≥ 5) of discharge liquids containing the same mixed powder and having different mixed powder volume ratios, replace the discharge liquid without the mixed powder in the above Step 2 with the discharge liquids containing the same mixed powder and having different mixed powder volume ratios, repeat the same procedure as in Step 2 n times, and obtain the dissipated energy W loss-mixed for a single pulse under n types of discharge liquids containing the same mixed powder and having different mixed powder volume ratios. The dissipated energy W loss-mixed for each single pulse when the discharge liquid contains the mixed powder, each mixed powder volume ratio, and the dissipated energy W loss for a single pulse when the discharge liquid in the above Step 2 does not contain the mixed powder are fitted to obtain the relational expression between the dissipated energy W loss-mixed for a single pulse when the discharge liquid contains the mixed powder, the mixed powder volume ratio, and the dissipated energy W loss for a single pulse when the discharge liquid does not contain the mixed powder under the same environmental conditions.

[0009] Step 5: Calculate the dissipated energy W loss-mixed for a single pulse when the discharge liquid contains the mixed powder based on the set mixed powder volume ratio according to the above relational expression between the dissipated energy W loss for a single pulse when the discharge liquid contains the mixed powder, the mixed powder volume ratio, and the dissipated energy W loss-mixed for a single pulse when the discharge liquid does not contain the mixed powder. The dissipated energy W loss-mixedWhen the etching solution contains the mixed powder, the volume V'' of a single etching pit is expressed by the following formula. JPEG2025100293000002.jpg953 Using this formula and the dissipated energy W of a single pulse when the etching solution contains the mixed powder corresponding to the calculated mixed powder volume ratio loss-mixed From this, the volume V'' of a single etching pit when the etching solution contains the mixed powder corresponding to the calculated mixed powder volume ratio is calculated, that is, regardless of whether the workpiece moves, the volume of a single etching pit when the etching solution contains the mixed powder corresponding to the calculated mixed powder volume ratio is calculated. Subsequently, using the relational expression a = εh, the calculated value of the volume V'' of a single etching pit when the etching solution contains the mixed powder corresponding to the calculated mixed powder volume ratio, and the above formula representing the volume V' of a single etching pit when the workpiece moves, the maximum depth h2 of a single etching pit when the etching solution contains the mixed powder corresponding to the calculated mixed powder volume ratio and the workpiece moves is calculated. When the etching solution contains the mixed powder corresponding to the calculated mixed powder volume ratio and the workpiece moves parallel at a preset speed, single-pulse etching test machining is continuously performed to obtain a plurality of consecutive etching pits when the workpiece moves. In each etching pit after the second one, the center of the etching pit is located at the apex of the semi-elliptical cone in the immediately preceding etching pit. Based on the maximum depth h2 of a single etching pit obtained by calculation when the etching solution contains the mixed powder corresponding to the calculated mixed powder volume ratio and the workpiece moves, the maximum depth h'' of the remaining etching pits other than the first one in the plurality of consecutive etching pits when the etching solution contains the mixed powder corresponding to the calculated mixed powder volume ratio and the workpiece moves is calculated.

[0010] Preferably, in the above step 2, the volume V1 of a single etching pit when the workpiece is stationary is calculated by the following formula. JPEG2025100293000003.jpg1747

[0011] Preferably, in the above step 2, the dissipated energy W of a single pulse when the discharge liquid does not contain mixed powder loss is calculated by the following formula. W loss =W input -W output W input =UIt W output =V1g In the formula, W input is the discharge energy of a single pulse, and W output is the pulse heat quantity of a single pulse.

[0012] Preferably, the same environmental conditions refer to the same discharge voltage, the same discharge current, the same discharge time, and the same workpiece material.

[0013] Preferably, the formula representing the volume V' of a single etching pit when the workpiece moves in the above step 3 and the above step 4 is the following formula. JPEG2025100293000004.jpg1689In the formula, a' is the radius of the arc at the top of the etching pit when the workpiece moves, h' is the maximum depth of the etching pit when the workpiece moves, l is the moving distance of the workpiece within the discharge time, and l = vt, where v is the translational speed of the workpiece.

[0014] Preferably, the above mixed powder volume ratio is 0.5 or less.

[0015] Preferably, the dissipated energy W of a single pulse when the discharge liquid contains mixed powder under the same environmental conditions obtained in the above step 4 loss-mixed and the mixed powder volume ratio and the dissipated energy W of a single pulse when the discharge liquid does not contain mixed powder loss The relational expression with is the following formula. JPEG2025100293000005.jpg1053In the formula, both λ and β are coefficients, and c is the mixed powder volume ratio.

[0016] Preferably, in the above step 5, when the mixed powder is contained in the discharge liquid and the workpiece moves, the maximum depth h'' of the remaining etching pits other than the first one in a plurality of consecutive etching pits is calculated by the following formula. JPEG2025100293000006.jpg1849

[0017] The present invention has the following beneficial effects. (1) The present invention obtains relevant data by performing a single-pulse etching test process when the workpiece is stationary under set environmental conditions, further derives the maximum depth of a single etching pit when the workpiece is moving, and further derives the maximum depth of the remaining etching pits other than the first one among a plurality of consecutive etching pits when the workpiece is moving, and later provides a basis for data regarding the surface roughness of the workpiece when performing single-pulse etching processing continuously. Specifically, the present invention performs a single-pulse etching test process on the workpiece once when the discharge liquid does not contain mixed powder and the workpiece is stationary, determines the value of the coefficient in the relational expression between the radius of the arc at the top of the etching pit and the maximum depth, and from the perspective of energy, establishes a calculation formula for the dissipated energy of a single single-pulse when the discharge liquid does not contain mixed powder, and provides data for deriving the maximum depth of a single etching pit when the discharge liquid does not contain mixed powder and the workpiece is moving. Furthermore, the present invention performs a single-pulse etching test process on the workpiece when the discharge liquid contains mixed powder with different mixed powder volume ratios and the workpiece is stationary, and obtains the dissipated energy of a single single-pulse with different mixed powder volume ratios. Through fitting, a relational expression between the dissipated energy of a single single-pulse when the discharge liquid contains mixed powder, the mixed powder volume ratio, and the dissipated energy of a single single-pulse when the discharge liquid does not contain mixed powder is obtained, and a calculation formula for the dissipated energy of a single single-pulse when the discharge liquid contains mixed powder is established, and provides data for deriving a calculation formula for the maximum depth of the etching pit when the discharge liquid contains mixed powder and the workpiece is moving, and further provides data for calculating the maximum depth of the remaining etching pits other than the first one among a plurality of consecutive etching pits when the discharge liquid contains the corresponding mixed powder volume ratio of mixed powder and the workpiece is moving, thereby providing a basis for data regarding the surface roughness of the workpiece when performing single-pulse etching processing continuously later. (2) The present invention establishes calculation formulas for the dissipated energy of a single pulse when the discharge liquid does not contain mixed powder and when it contains mixed powder, based on the discharge voltage, discharge current, discharge time, workpiece material, and volume of the etching pit, thereby providing a basis for data regarding the surface roughness of the workpiece when single-pulse etching processing is continuously performed by different discharge voltages, different discharge currents, different discharge times, or different workpiece materials later.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0019] The present invention will be further described below with reference to the drawings. A specific example of the method for measuring the maximum depth of the discharge continuous etching pit of the present invention includes the following steps 1 to 5.

[0020] Step 1: Set the discharge time, discharge voltage, and discharge current for the single-pulse etching test processing.

[0021] Step 2: When the mixed powder is not included in the discharge liquid and the workpiece is stationary, perform a single-pulse etching test process on the workpiece once to obtain a single etching pit when the workpiece is stationary. The etching pit when the workpiece is stationary is spherical-crowned as shown in FIG. 1. Using computer image recognition technology, measure the radius a1 of the arc at the topmost part and the maximum depth h1 of the single etching pit when the workpiece is stationary, and calculate the volume V1 of the single etching pit when the workpiece is stationary from the measured values, that is, the volume of the spherical crown. Subsequently, calculate the dissipated energy W of a single pulse when the mixed powder is not included in the discharge liquid. loss Calculate. Here, the volume V1 of the single etching pit when the workpiece is stationary is calculated by the following formula. JPEG2025100293000007.jpg1747 The dissipated energy W of a single pulse when the mixed powder is not included in the discharge liquid loss Is calculated by the following formula. W loss =W input -W output W input =UIt W output =V1g In the formula, W input Is the discharge energy of a single pulse, U is the discharge voltage, I is the discharge current, t is the discharge time of a single pulse, W output Is the pulse heat quantity of a single pulse, and g is the latent heat of phase change of the workpiece material. Here, when performing the single-pulse etching test process, the electrode moves downward to a predetermined lowest point, starts discharging, and then the electrode moves upward. The discharge liquid flowing between the electrode and the workpiece before the discharge of the electrode ends takes away the etched solid particles.

[0022] Step 3: When the mixed powder is not included in the discharge liquid and the workpiece moves in parallel at a preset speed, a single-pulse etching test process is performed on the workpiece once to obtain a single etching pit when the workpiece moves. As shown in FIG. 2, the etching pit when the workpiece moves has a shape that combines half of a spherical crown and a semi-elliptical cone with a semi-ellipse that is the central cross-section of the spherical crown as the bottom surface. Under the same environmental conditions, regardless of whether the workpiece moves or not, the dissipated energy of a single pulse is equal to each other. And under the same environmental conditions, the volume V' of a single etching pit when the workpiece moves is equal to the volume V1 of a single etching pit when the workpiece is stationary. Here, the same environmental conditions refer to the same discharge voltage, the same discharge current, the same discharge time, and the same workpiece material. At the same time, under the same environmental conditions, the relationship between the radius a' of the arc at the top of a single etching pit and the maximum depth h' when the workpiece moves is the same as the relationship between the radius a1 of the arc at the top of a single etching pit and the maximum depth h1 when the workpiece is stationary, and is uniformly expressed by the following relational expression. a = εh In the formula, a and h are the radius of the arc at the top of the etching pit and the maximum depth, respectively, and ε is a coefficient. The value range of ε is 1.20 to 1.40. Here, after the metal workpiece receives arc energy at a certain point and diffuses, the ratio of the radius of the arc at the top of the generated etching pit to the maximum depth is affected by the speed ratio of heat transfer in the axial direction and heat transfer in the radial direction. The speed ratio of heat transfer in the axial direction and heat transfer in the radial direction of the metal workpiece is constant. That is, the value of ε is constant and is not affected by whether the workpiece moves or not and whether the mixed powder is included in the discharge liquid or not. Calculate the value of the coefficient ε from the radius a1 of the arc at the top of a single etching pit and the maximum depth h1 when the workpiece is stationary, as measured in Step 2 above, and obtain the relational expression between the radius a' of the arc at the top of a single etching pit and the maximum depth h' when the workpiece is moving. Further, based on the relational expression between the radius a' of the arc at the top of a single etching pit and the maximum depth h' when the workpiece is moving, and the value of the volume V1 of a single etching pit when the workpiece is stationary under the same environmental conditions obtained in Step 2 above, substitute V1 for V' in the following formula (the formula for the sum of the volume of a hemispherical cap and the volume of a semi-elliptical cone) representing the volume V' of a single etching pit when the workpiece is moving, to calculate the maximum depth h' of a single etching pit when the workpiece is moving. Here, the volume V' of a single etching pit when the workpiece is moving is represented by the following formula. JPEG2025100293000008.jpg1689In the formula, a' and h' are the radius of the arc at the top of the etching pit and the maximum depth when the workpiece is moving, l is the moving distance of the workpiece during the discharge time, where l = vt, and v is the translational speed of the workpiece.

[0023] Step 4: Prepare five types of discharge liquids containing the same mixed powder and having different mixed powder volume ratios (the ratio of the volume of the mixed powder to the volume of the discharge liquid after adding the mixed powder). Here, the mixed powder volume ratio is set not to exceed 0.5. Next, replace the discharge liquid without the mixed powder in Step 2 above with the discharge liquids containing the same mixed powder and having different mixed powder volume ratios, and repeat the same procedure as in Step 2 five times to obtain the value of the dissipated energy W loss-mixed of a single pulse for each of the five types of discharge liquids containing the same mixed powder and having different mixed powder volume ratios. That is, measure the radius of the arc at the top of the etching pit and the maximum depth, calculate the volume of the etching pit from the measured values, and calculate the dissipated energy W loss-mixed from the calculated volume and the like. Subsequently, the dissipated energy W of each single pulse when the discharge liquid contains the mixed powder loss-mixed, the volume ratio of each mixed powder and the energy dissipation W of a single pulse when the discharge liquid in step 2 does not contain the mixed powder loss are fitted, and the energy dissipation W of a single pulse when the discharge liquid contains the mixed powder under the same environmental conditions loss-mixed , the volume ratio of the mixed powder, and the energy dissipation W of a single pulse when the discharge liquid does not contain the mixed powder loss to obtain the following equation which is the relational expression among them. JPEG2025100293000009.jpg1053In the formula, both λ and β are coefficients, and c is the volume ratio of the mixed powder.

[0024] Step 5: Based on the set volume ratio of the mixed powder, the energy dissipation W of a single pulse when the discharge liquid contains the mixed powder loss-mixed , the volume ratio of the mixed powder, and the energy dissipation W of a single pulse when the discharge liquid does not contain the mixed powder loss According to the above relational expression, the energy dissipation W of a single pulse when the discharge liquid contains the mixed powder with the corresponding volume ratio of the mixed powder loss-mixed is calculated. The energy dissipation W of a single pulse when the discharge liquid contains the mixed powder loss-mixed is expressed by the following formula using the volume V’’ of a single etching pit when the discharge liquid contains the mixed powder. JPEG2025100293000010.jpg953From this formula and the calculated energy dissipation W of a single pulse when the discharge liquid contains the mixed powder with the corresponding volume ratio of the mixed powder loss-mixed , the volume V’’ of a single etching pit when the discharge liquid contains the mixed powder with the corresponding volume ratio of the mixed powder is calculated, that is, regardless of whether the workpiece moves or not, the volume of a single etching pit when the discharge liquid contains the mixed powder with the corresponding volume ratio of the mixed powder is calculated. Subsequently, based on the relational expression a = εh (where a2 = εh2) and the value of the volume V’’ of a single etching pit in the case where the discharge liquid contains mixed powder with a corresponding mixed powder volume ratio, in the above formula representing the volume V’ of a single etching pit when the workpiece moves, by substituting the value of V’’ into V’ and substituting h2 into h’, the maximum depth h2 of a single etching pit when the discharge liquid contains mixed powder with a corresponding mixed powder volume ratio and the workpiece moves is calculated. When the discharge liquid contains mixed powder with a corresponding mixed powder volume ratio and the workpiece moves in parallel at a preset speed, single-pulse etching test machining is continuously performed to obtain a plurality of consecutive etching pits when the workpiece moves. As shown in FIG. 3, in each etching pit after the second one, the center of the etching pit is located at the apex of the semi-elliptical cone in the immediately preceding etching pit. Here, the center of the etching pit is the center of the semi-ellipse that is the bottom surface of the semi-elliptical cone in that etching pit. Based on the maximum depth h2 of a single etching pit when the discharge liquid contains mixed powder with a corresponding mixed powder volume ratio and the workpiece moves, which is obtained by calculation, the maximum depth h’’ of the remaining etching pits other than the first one in a plurality of consecutive etching pits when the discharge liquid contains mixed powder with a corresponding mixed powder volume ratio and the workpiece moves is calculated, providing a basis for data regarding the roughness of the workpiece surface when single-pulse etching machining is continuously performed. Here, the maximum depth h’’ of the remaining etching pits other than the first one in a plurality of consecutive etching pits when the discharge liquid contains mixed powder and the workpiece moves is obtained by the following formula. JPEG2025100293000011.jpg1849 Here, the length of d in FIG. 3 is approximately equal to 1.2h2.

Claims

1. A method for measuring the maximum depth of a discharge continuous etching pit, characterized by including the following steps 1 to 5. Step 1: Set the discharge time, discharge voltage, and discharge current of the single-pulse etching test process. Step 2: When the discharge liquid does not contain mixed powder and the workpiece is stationary, perform a single pulse etching test process on the workpiece once to obtain a single etching pit when the workpiece is stationary. When the workpiece is stationary, the etching pit is a spherical crown shape. The radius a of the most apex of the single etching pit when the workpiece is stationary １ and maximum depth h １ From the measured values, the volume V of a single etching pit when the workpiece is stationary is calculated. １ Then, the dissipated energy W of one single pulse when the discharge liquid does not contain mixed powder is calculated. ｌｏｓｓ is calculated using the following formula: W ｌｏｓｓ = UIt - V １ g In the formula, U is the discharge voltage, I is the discharge current, t is the discharge time, and g is the latent heat of phase change of the workpiece material. Step 3: When the discharge liquid does not contain mixed powder and the workpiece moves parallel at a preset speed, perform a single-pulse etching test process on the workpiece once to obtain a single etching pit when the workpiece moves. The etching pit when the workpiece moves is a shape combined with half of a spherical cap and a semi-elliptical cone with a semi-ellipse, which is the central cross-section of the spherical cap, as the bottom surface. Under the same environmental conditions, the volume V' of a single etching pit when the workpiece moves is equal to the volume V of a single etching pit when the workpiece is stationary. １ Under the same environmental conditions, the relationship between the radius a' of the arc at the topmost part and the maximum depth h' of a single etching pit when the workpiece moves is the same as the relationship between the radius a of the arc at the topmost part and the maximum depth h １ of a single etching pit when the workpiece is stationary, and is uniformly expressed by the following relational expression. １ Under the same environmental conditions, the relationship between the radius a' of the arc at the topmost part and the maximum depth h' of a single etching pit when the workpiece moves is the same as the relationship between the radius a of the arc at the topmost part and the maximum depth h a = εh In the formula, a and h are the radius of the arc and the maximum depth of the top of the etching pit, respectively, and ε is a coefficient. The radius a of the arc at the top of the etching pit when the measured workpiece is stationary １ and the maximum depth h １ From these, the value of the coefficient ε is calculated, and the relational expression between the radius a' of the arc at the top of a single etching pit and the maximum depth h' when the workpiece moves is obtained. Using this relational expression, the value of the volume V １ of the etching pit and the expression representing the volume V' of a single etching pit when the workpiece moves, the maximum depth h' of a single etching pit when the workpiece moves is calculated. Step 4: Prepare n types (n ≧ 5) of discharge liquids that contain the same mixed powder and have different mixed powder volume ratios. Replace the discharge liquid without the mixed powder in Step 2 with the discharge liquids that contain the same mixed powder and have different mixed powder volume ratios, and repeat the same procedure as in Step 2 n times to obtain the single-pulse dissipation energy W ｌｏｓｓ－ｍｉｘｅｄ for the n types of discharge liquids that contain the same mixed powder and have different volume ratios of the mixed powder. Subsequently, the dissipated energy W of each single pulse when the discharge liquid contains the mixed powder ｌｏｓｓ－ｍｉｘｅｄ , the volume ratio of each mixed powder, and the dissipated energy W of a single pulse when the discharge liquid does not contain the mixed powder in Step 2 ｌｏｓｓ are fitted, and the dissipated energy W of a single pulse when the discharge liquid contains the mixed powder under the same environmental conditions ｌｏｓｓ－ｍｉｘｅｄ , the volume ratio of the mixed powder, and the dissipated energy W of a single pulse when the discharge liquid does not contain the mixed powder ｌｏｓｓ to obtain the relational expression therebetween. Step 5: Based on the set mixed powder volume ratio, the single-pulse dissipation energy W when the discharge liquid contains the mixed powder ｌｏｓｓ－ｍｉｘｅｄ and the mixed powder volume ratio, and the single-pulse dissipation energy W when the discharge liquid does not contain the mixed powder ｌｏｓｓ According to the above relational expression, the single-pulse dissipation energy W when the discharge liquid contains the mixed powder with the corresponding mixed powder volume ratio ｌｏｓｓ－ｍｉｘｅｄ is calculated. The dissipated energy W per single pulse when the discharge liquid contains mixed powder ｌｏｓｓ－ｍｉｘｅｄ is expressed by the following formula using the volume V'' of a single etching pit when the discharge liquid contains mixed powder. This equation and the dissipated energy W for a single pulse when the calculated discharge liquid contains the mixed powder with the corresponding mixed powder volume ratio ｌｏｓｓ－ｍｉｘｅｄ From this, the volume V'' of a single etching pit when the discharge liquid contains the mixed powder with the corresponding mixed powder volume ratio is calculated, that is, regardless of whether the workpiece moves, the volume of a single etching pit when the discharge liquid contains the mixed powder with the corresponding mixed powder volume ratio is calculated. Subsequently, using the relational expression a = εh, the value of the volume V'' of a single etching pit when the discharge liquid contains the mixed powder with the corresponding mixed powder volume ratio, and the above formula representing the volume V' of a single etching pit when the workpiece moves, the maximum depth h of a single etching pit when the discharge liquid contains the mixed powder with the corresponding mixed powder volume ratio and the workpiece moves is calculated. ２ is calculated. When the discharge liquid contains mixed powder with a corresponding mixed powder volume ratio and the workpiece moves parallel at a preset speed, continuously perform the single-pulse etching test process to obtain a plurality of consecutive etching pits when the workpiece moves. In each etching pit after the second one, the center of the etching pit is located at the apex of the semi-elliptical cone in the previous etching pit. The maximum depth h of a single etching pit when the discharge liquid contains mixed powder with a corresponding mixed powder volume ratio obtained by calculation and the workpiece moves ２ Based on this, the maximum depth h'' of the remaining etching pits other than the first one among a plurality of consecutive etching pits when the discharge liquid contains mixed powder with a corresponding mixed powder volume ratio and the workpiece moves is calculated.

2. In the step 2, the volume V of a single etching pit when the workpiece is stationary １ is calculated by the following formula, and the method for measuring the maximum depth of the discharge continuous etching pit according to claim 1 is characterized by this.

3. In the step 2, the dissipated energy W of a single pulse when the mixed powder is not included in the discharge liquid ｌｏｓｓ is calculated by the following formula, and the method for measuring the maximum depth of the discharge continuous etching pit according to claim 1 is characterized by this. W ｌｏｓｓ = W ｉｎｐｕｔ - W ｏｕｔｐｕｔ W ｉｎｐｕｔ = UIT W ｏｕｔｐｕｔ = V １ g where W ｉｎｐｕｔ is the discharge energy per single pulse, and W ｏｕｔｐｕｔ is the pulse calorific value per single pulse.

4. The same environmental conditions refer to the same discharge voltage, the same discharge current, the same discharge time, and the same workpiece material. The method for measuring the maximum depth of a discharge continuous etching pit according to Claim 1, characterized by this.

5. The formula representing the volume V' of a single etching pit when the workpiece moves in Step 3 and Step 4 is the following formula. The method for measuring the maximum depth of a discharge continuous etching pit according to Claim 1, characterized by this. In the formula, a' is the radius of the arc at the top of the etching pit when the workpiece moves, h' is the maximum depth of the etching pit when the workpiece moves, l is the moving distance of the workpiece during the discharge time, and l = vt, where v is the parallel moving speed of the workpiece.

6. The mixed powder volume ratio is 0.5 or less. The method for measuring the maximum depth of a discharge continuous etching pit according to Claim 1, characterized by this.

7. The dissipated energy W of a single pulse when the discharge liquid contains mixed powder under the same environmental conditions obtained in the step 4 above ｌｏｓｓ－ｍｉｘｅｄ and the volume ratio of the mixed powder, and the dissipated energy W of a single pulse when the discharge liquid does not contain the mixed powder ｌｏｓｓ The measurement method of the maximum depth of the discharge continuous etching pit according to claim 1, wherein the relational expression with is the following formula In the formula, both λ and β are coefficients, and c is the mixed powder volume ratio.

8. In the step 5, when the mixed powder is included in the discharge liquid and the workpiece moves, the maximum depth h'' of the remaining etching pits other than the first one in a plurality of consecutive etching pits is calculated by the following formula. The method for measuring the maximum depth of the discharge continuous etching pits according to claim 1 is characterized by this.

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