A method for correcting deformation of a large irregular casting

Abstract

A method for correcting deformation in large irregular castings includes the following steps: S1, scanning the workpiece with a scanner to obtain its three-dimensional data; S2, comparing the workpiece's three-dimensional data with the design data model to identify the theoretical deformation location; S3, longitudinally slicing the theoretical deformation location, setting the slice with the largest deformation as the reference slice, and creating a conformal template at the reference slice; S4, placing the conformal template at the reference slice location of the workpiece and comparing it with the workpiece, and calculating the actual deformation value; S5, correcting the workpiece using a thermal straightening method based on the actual deformation value; S6, comparing the conformal template with the corrected workpiece. If the actual deformation value after correction is less than the standard tolerance value, proceed to step S7; otherwise, repeat steps S5-S6. S7, scanning the corrected workpiece with a scanner to obtain its three-dimensional data after correction, and comparing it with the design data model. If the deformation is less than the standard tolerance value, the correction is complete; otherwise, repeat steps S2-S6 until the workpiece's deformation is less than the set tolerance value. This solves the problem of not being able to accurately locate and correct the deformation position of irregular workpieces, thus avoiding the scrapping of workpieces caused by this.

Description

Technical Field

[0001] This invention relates to the field of shipbuilding technology, and specifically to a method for correcting deformation of large irregular castings. Background Technology

[0002] Castings often deform during shrinkage or heat treatment, which can be corrected through heat straightening, welding, or pressure straightening. For regular products, the location and degree of deformation can be marked manually or by scribing. However, for large, irregular castings, such as marine components, the parts are irregularly shaped, asymmetrical, lack a reference point, or have a reference point more than 10 meters away, and the surfaces are not perpendicular or parallel. Once deformation occurs, it is impossible to find the location and degree of deformation using traditional manual measurement, scribing, or even machine tool marking. Therefore, how to identify the problem, implement it on-site, and accurately correct it becomes a challenge in straightening technology. Summary of the Invention

[0003] In view of the problems and shortcomings of the existing technology, the present invention provides a method for correcting the deformation of large irregular castings.

[0004] The technical solution of this invention is as follows:

[0005] A method for correcting deformation in large, irregular castings, characterized by the following steps:

[0006] S1, Scan the workpiece to obtain its three-dimensional data;

[0007] S2, compare the three-dimensional data of the workpiece with the design data model to find the theoretical deformation location;

[0008] S3, perform longitudinal slicing on the theoretical deformation location, set the slice at the location with the largest deformation as the reference slice, and create a conformal template at the reference slice, including the following steps:

[0009] S31: Perform longitudinal slicing at the theoretical deformation position, compare the difference between the longitudinal slice and the workpiece 3D data and the design data model contour line, take the longitudinal slice with the largest difference as the reference slice O, take the outer contour surface of the design data model that intersects with the reference slice O and corresponds to the theoretical deformation position as the measurement surface N, and define any surface of the design data model that intersects with the reference slice O and is not deformed as the reference surface M.

[0010] S32: Obtain the intersection lines m and n of the reference slice with the reference surface M and the measurement surface N. Then, determine the reference edge a and the measurement edge b of the conformal template according to the position and size of the intersection lines m and n. Make the conformal template according to the workpiece size.

[0011] S4. Place the conformal template on the workpiece at the deformation location for comparison and calculate the actual deformation value at the workpiece deformation location.

[0012] S5. The deformation position of the workpiece is corrected by using the thermal straightening method based on the actual deformation value of the workpiece.

[0013] S6. Compare the conformal template with the corrected workpiece. If the actual deformation value after correction is less than the standard tolerance value T, proceed to step S7; otherwise, proceed to step S5.

[0014] S7. Scan the corrected workpiece to obtain its three-dimensional data and compare it with the design data model. If the deformation is less than the standard tolerance value, the correction is complete. Otherwise, repeat steps S2-S6 until the deformation of the workpiece is less than the standard tolerance value.

[0015] In step S32, the dimensions of the reference edge a and the measuring edge b of the conformal template are larger than the corresponding dimensions of the reference surface M and the measuring surface N of the workpiece that it mates with.

[0016] Step S4 is achieved through the following specific operations:

[0017] S41: Make the reference edge a of the conformal template match the reference surface A of the workpiece, and the measuring edge b match the deformable surface B of the workpiece, where the reference surface A is the surface on the workpiece that is opposite to the reference surface M in the design data model, and the deformable surface B is the surface that is opposite to the measuring surface N in the design data model.

[0018] S42: Measure the longitudinal difference between the deformed surface B and the measured edge b, mark the position that exceeds the tolerance as the actual deformation position, and record the actual deformation value δ1.

[0019] Step S5 is achieved through the following specific operations:

[0020] S51: Calculate the correction value δ2 of the workpiece based on the actual deformation value δ1 of the workpiece;

[0021] S52: Place the special platform for straightening on the kiln car of the heat treatment kiln and level it with a spirit level;

[0022] S53: Place the workpiece stably on the straightening platform, and place steel pads below the non-deformed parts of the workpiece, and place wooden pads with a height greater than the straightening value below the deformed parts of the workpiece.

[0023] S54: Two pressure irons are set above the workpiece. One is a fixed pressure iron, which is placed above the side opposite to the deformed position of the workpiece and is fixedly connected to the special platform. The other is a straightening pressure iron, which is placed directly above the deformed position of the workpiece.

[0024] The formula for calculating the weight of the straightening weight is: G J =k*S min*σS / g, where k represents the adjustment coefficient, with a value range of 0.01 - 0.015; S min represents the minimum cross-sectional area at the deformation position; σ S represents the yield stress of the workpiece material; g represents the acceleration due to gravity;

[0025] S55: Push the kiln car into the heat treatment kiln for heating and correction until it reaches the plastic softening state as a whole, and then perform slow cooling in the furnace.

[0026] The height of the wooden cushion block in step S53 is 2 - 10 mm larger than the correction value δ2. The weight of the fixed iron in step S54 is not less than 3 times the weight of the workpiece.

[0027] The above step S55 is realized through the following specific operations:

[0028] Heat the heat treatment kiln to 50°C - 100°C above the plastic deformation temperature of the workpiece, hold for 4 - 7 hours, perform slow cooling in the furnace after reaching the plastic softening state as a whole, and take out of the kiln when the temperature drops below 300°C. The heating rate of the heat treatment kiln during heating is controlled at 30 - 50°C / h.

[0029] The above step S6 is realized through the following specific operations:

[0030] S61: Cool the workpiece to below 100°C and perform shot blasting to clean the iron oxide on the surface of the workpiece;

[0031] S62: Place the conforming template at the deformed position of the corrected workpiece, measure the actual deformation value δ'1 after correction and compare it with the standard tolerance T to judge the correction result. If δ'1 < T, then execute step S7; otherwise, execute step S5.

[0032] The beneficial effects of the present invention are:

[0033] This method solves the problem that the deformed position of irregular workpieces cannot be accurately found and accurately corrected, reduces the situation where the workpiece fails to meet the manufacturing tolerance requirements due to workpiece deformation, incorrect correction or overcorrection, ultimately leading to workpiece scrapping. Moreover, this method is accurate, reliable, simple to operate, and has an extremely low production process cost, which can effectively reduce production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram for comparing the three-dimensional data of the workpiece with the design data model and slicing;

[0035] Figure 2 It is a schematic diagram for comparing the conforming template with the workpiece;

[0036] Figure 3 It is a process setup diagram of the workpiece before entering the cooling kiln;

[0037] 1. Design data model; 2. 3D data of the workpiece; 3. Workpiece; 4. Flexible template; 5. Special platform for straightening; 6. Straightening pressure plate; 7. Fixing pressure plate. Detailed Implementation

[0038] The technical means adopted to achieve the intended purpose of the present invention will be further described below with reference to the accompanying drawings in the embodiments of the present invention.

[0039] S1, Scan the workpiece to obtain its three-dimensional data;

[0040] In practice, the workpiece is first placed on the workpiece platform, and then the operator uses a handheld 3D laser scanner to scan the workpiece to obtain complete three-dimensional data, including geometric and dimensional information, which is then transmitted and viewed via computer.

[0041] Specifically, taking a marine support as an example, it is placed horizontally on a workpiece platform, and a handheld 3D laser scanner is used to scan it to obtain the three-dimensional data of the support. The obtained data is then uploaded to the CAD software module on the computer for viewing.

[0042] S2, compare the three-dimensional data of the workpiece with the design data model to find the theoretical deformation location;

[0043] The workpiece 3D data obtained in the previous step is retrieved and compared with the workpiece's design 3D model to find the theoretical deformation location.

[0044] In practice, the 3D workpiece data and design data model obtained after the previous scanning step are both imported into the software for comparison. Specifically, the comparison method involves setting a tolerance range in the software according to the standard tolerance T. When the deformation difference exceeds the standard tolerance range, it is determined to be the theoretical deformation location, and a color-coded warning is displayed. Specifically, the standard tolerance value T is determined according to the casting dimensional tolerance table in GB / T 6414-2017.

[0045] For example, the three-dimensional data of the marine support obtained above is compared with the design data model of the marine support in the CAD software module, and the standard tolerance is set to 10mm in the software. When the three-dimensional data of the marine support is deformed by more than 10mm compared with the design data model, the corresponding deformation position will be automatically highlighted.

[0046] S3, Based on the theoretical deformation position, create a conformal template at the deformation position;

[0047] S31: Perform longitudinal slicing at the theoretical deformation point, compare the difference between the longitudinal slice and the workpiece 3D data and the design data model contour line, take the longitudinal slice with the largest difference as the reference slice O, take the outer contour surface of the design data model that intersects with the reference slice O and corresponds to the theoretical deformation position as the measurement surface N, and define any surface of the design data model that intersects with the reference slice O and is not deformed as the reference surface M.

[0048] S32: Obtain the intersection lines m and n of the reference surface M and the measurement surface N of the reference slice and the workpiece design data model, and then determine the reference edge a and the measurement edge b of the conformal template according to the position and size of the intersection lines m and n.

[0049] S33: Make a conformal template according to the workpiece size. Specifically, the dimensions of the reference side a and the measuring side b of the conformal template are slightly larger than the corresponding dimensions of the reference surface and the deformable surface of the workpiece that it mates with.

[0050] For example, the length of the reference edge 'a' of the conformal template is 5-10 mm longer than the extension length of the reference surface 'M' of the marine support, and the length of the measuring edge 'b' is 10-15 mm longer than the extension length of the deformable surface of the marine support. The dimensions of the conformal template's edges can be determined based on the principle of available space and material conservation. In this embodiment, the height of the conformal template on the side closer to the reference edge is greater than the height on the side farther from the reference edge. This is to ensure that the reference edge is completely fitted with the reference surface of the workpiece. On the side farther from the reference edge, only the bottom measuring edge needs to fit with the deformable surface of the workpiece, so the height dimension is not limited. To save materials, the high pressure is designed to be half the height of the side adjacent to the reference edge.

[0051] S4. Place the conformal template on the workpiece at the deformation location for comparison and calculate the actual deformation value at the workpiece deformation location.

[0052] S41: Place the conformal template at the reference slice position of the workpiece, and make its reference edge a match the reference surface A of the workpiece, and its measuring edge b match the deformable surface B of the workpiece. The reference surface A is the surface on the workpiece that is opposite to the reference surface M in the design data model, and the deformable surface B is the surface that is opposite to the measuring surface N in the design data model.

[0053] Specifically, it is necessary to ensure that the reference edge a is completely in contact with the reference surface A of the workpiece, and that the measuring edge b is in contact with the non-deformed position of the deformed surface B of the workpiece. A gap should appear at the deformed position, which is the actual deformation height difference.

[0054] S42: Then measure the longitudinal difference between the deformed surface B and the measured edge b, mark the position that exceeds the tolerance as the actual deformation position, and record the actual deformation value δ1.

[0055] S5. The deformation position of the workpiece is corrected by using the thermal straightening method based on the actual deformation value of the workpiece.

[0056] S51: Calculate the correction value δ2 of the workpiece based on the actual deformation value δ1 of the workpiece;

[0057] S52: Place the special platform for straightening on the kiln car of the heat treatment kiln and level it with a spirit level;

[0058] S53: Place the workpiece stably on the straightening platform, and place a steel pad under the non-deformed position of the workpiece and a wooden pad under the deformed position of the workpiece, with the height of the wooden pad being 2 to 10 mm greater than the straightening value.

[0059] S54: Two pressure irons are set above the workpiece. One is a fixed pressure iron, which is placed above the opposite side of the deformed position of the workpiece and is fixedly connected to a special platform to ensure the stability of the workpiece when it is heated and expanded. The other is a straightening pressure iron, which is placed directly above the deformed position of the workpiece.

[0060] The weight of the fixed pressure iron shall not be less than three times the weight of the workpiece; the formula for calculating the weight of the straightening pressure iron is: G J =k*S min *σ S / g, where k represents an adjustment coefficient, ranging from 0.01 to 0.015; S min σ represents the minimum cross-sectional area at the deformation location; S represents the yield stress of the workpiece material; g represents the acceleration due to gravity.

[0061] S55: Push the kiln car into the heat treatment kiln for heating and straightening. Heat the heat treatment kiln to 50℃-100℃ above the plastic deformation temperature of the workpiece. Control the heating rate at 30-50℃ / h and hold for 4-7 hours to ensure that the internal and external temperatures of the workpiece are consistent and the whole workpiece reaches a plastic softening state. Then, slowly cool it in the furnace to release the stress generated by the straightening deformation. When the temperature drops below 300℃, remove it from the kiln.

[0062] After the kiln car enters the heat treatment kiln, as the temperature rises, the wooden pads placed below the deformation position burn. The workpiece loses its support point below the deformation position and is subjected to the downward gravity of the straightening pressure iron. At the same time, as the temperature rises, the workpiece reaches a plastic softening state, and the workpiece deforms in the opposite direction, thereby gradually offsetting the deformation value and correcting the deformation position of the workpiece. After correction, the workpiece is slowly cooled in the furnace to release the stress generated by the correction deformation, eliminate residual stress, and ensure that it does not spring back after exiting the kiln.

[0063] S6. Compare the conformal template with the corrected workpiece. If the actual deformation value after correction is less than the standard tolerance value, proceed to step S7; otherwise, proceed to step S5.

[0064] S61: After exiting the kiln, the workpiece is cooled to below 100℃ and shot blasted to remove iron oxide from the surface of the workpiece;

[0065] S62: Place the profiling template at the slicing position of the corrected workpiece, measure the actual deformation value δ'1 after correction and compare it with the standard tolerance T to judge the correction result. If δ'1 < T, execute step S7; otherwise, execute step S5.

[0066] S7. Scan the corrected workpiece with a scanner to obtain the three-dimensional data of the corrected workpiece and compare it with the design data model. If the deformation amount is less than the standard tolerance value T, the correction is completed; otherwise, repeat steps S2 - S6 until the deformation amount of the workpiece is less than the standard tolerance value.

[0067] The above are the preferred embodiments of the present invention. However, the present invention is not limited to the above embodiments and examples. Within the scope of knowledge possessed by those skilled in the art, various changes, equivalent replacements, improvements, etc. made without departing from the concept of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for correcting deformation in large, irregular castings, characterized in that, Includes the following steps: S1, Scan the workpiece to obtain its three-dimensional data; S2, compare the three-dimensional data of the workpiece with the design data model to find the theoretical deformation location; S3, perform longitudinal slicing on the theoretical deformation location, set the slice at the location with the largest deformation as the reference slice, and create a conformal template at the reference slice, including the following steps: S31: Perform longitudinal slicing at the theoretical deformation position, compare the difference between the longitudinal slice and the workpiece 3D data and the design data model contour line, take the longitudinal slice with the largest difference as the reference slice O, take the outer contour surface of the design data model that intersects with the reference slice O and corresponds to the theoretical deformation position as the measurement surface N, and define any surface of the design data model that intersects with the reference slice O and is not deformed as the reference surface M. S32: Obtain the intersection lines m and n of the reference slice with the reference surface M and the measurement surface N. Then, determine the reference edge a and the measurement edge b of the conformal template according to the position and size of the intersection lines m and n. Make the conformal template according to the workpiece size. S4. Place the conformal template on the workpiece at the deformation location for comparison and calculate the actual deformation value at the workpiece deformation location. S5. The deformation position of the workpiece is corrected by using the thermal straightening method based on the actual deformation value of the workpiece. S6. Compare the conformal template with the corrected workpiece. If the actual deformation value after correction is less than the standard tolerance value T, proceed to step S7; otherwise, proceed to step S5. S7. Scan the corrected workpiece to obtain its three-dimensional data and compare it with the design data model. If the deformation is less than the standard tolerance value, the correction is complete. Otherwise, repeat steps S2-S6 until the deformation of the workpiece is less than the standard tolerance value.

2. The correction method according to claim 1, characterized in that, In step S32, the dimensions of the reference edge a and the measuring edge b of the conformal template are larger than the corresponding dimensions of the reference surface M and the measuring surface N of the workpiece that it mates with.

3. The correction method according to claim 1, characterized in that, Step S4 is achieved through the following specific operations: S41: Make the reference edge a of the conformal template match the reference surface A of the workpiece, and the measuring edge b match the deformable surface B of the workpiece, where the reference surface A is the surface on the workpiece that is opposite to the reference surface M in the design data model, and the deformable surface B is the surface that is opposite to the measuring surface N in the design data model. S42: Measure the longitudinal difference between the deformed surface B and the measured edge b, mark the position that exceeds the tolerance as the actual deformation position, and record the actual deformation value δ1.

4. The correction method according to claim 3, characterized in that, Step S5 is achieved through the following specific operations: S51: Calculate the correction value δ2 of the workpiece based on the actual deformation value δ1 of the workpiece; S52: Place the special platform for straightening on the kiln car of the heat treatment kiln and level it with a spirit level; S53: Place the workpiece stably on the straightening platform, and place steel pads below the non-deformed parts of the workpiece, and place wooden pads with a height greater than the straightening value below the deformed parts of the workpiece. S54: Two pressure irons are set above the workpiece. One is a fixed pressure iron, which is placed above the side opposite to the deformed position of the workpiece and is fixedly connected to the special platform. The other is a straightening pressure iron, which is placed directly above the deformed position of the workpiece. The formula for calculating the weight of the straightening weight is: G J =k*S min *σ S / g, where k represents an adjustment coefficient, ranging from 0.01 to 0.015; S min σ represents the minimum cross-sectional area at the deformation location; S The workpiece material represents the yield stress; g represents the acceleration due to gravity. S55: Push the kiln car into the heat treatment kiln for heating and rectification until the whole reaches the plastic softening state, and then carry out slow cooling in the furnace.

5. The correction method according to claim 4, characterized in that, In step S53, the height of the wooden spacer block is 2 - 10 mm greater than the rectification value δ2.

6. The correction method according to claim 4, characterized in that, In step S54, the weight of the fixed iron weight is not less than 3 times the weight of the workpiece.

7. The correction method according to claim 4, characterized in that, Step S55 is achieved through the following specific operations: Heat the heat treatment kiln to 50℃ - 100℃ above the plastic deformation temperature of the workpiece, hold for 4 - 7 hours, carry out slow cooling in the furnace after the whole reaches the plastic softening state, and take out of the kiln when the temperature drops below 300℃.

8. The correction method according to claim 7, characterized in that, When heating the heat treatment kiln, the heating rate is controlled at 30 - 50℃ / h.

9. The correction method according to claim 1, characterized in that, Step S6 is achieved through the following specific operations: S61: Cool the workpiece to below 100℃, and shot blast the iron oxide on the surface of the workpiece; S62: Place the profile template at the deformed position of the rectified workpiece, measure the actual deformation value δ'1 after rectification and compare it with the standard tolerance T to judge the rectification result. If δ'1 < T, then execute step S7, otherwise execute step S5.

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