Method for testing load distribution of castings

Abstract

The present application belongs to the technical field of casting detection, and particularly relates to a load distribution test method for a steam turbine outer cylinder steel casting. First, the casting is placed on a machining platform, and then support points, detection points and jacking points are determined according to the structure of the casting. The support points are the bottoms of the four corners of the casting, i.e. the stable support positions of the casting are determined. The jacking points are close to the support points, i.e. the position points at which the jacking assembly jacks up the casting. The detection points are arranged at the planes of the upper surfaces of the four corner ends of the casting close to the jacking points, for setting dial gauges at the detection points to detect the actual jacking amounts, and the load distribution state of the casting is measured by comparing the measured values of the dial gauges to determine the subsequent test process. The function of simultaneously measuring the jacking amounts of the two sides at the front end or the rear end of the casting is realized, and the absolute readings of the pressure gauges of the jacking pieces do not need to be recorded, but the difference between the display values of the dial gauges is used to set the gasket set, so that the effect of efficient, rapid and accurate testing is achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of casting detection, and particularly relates to a load distribution test method for a steam turbine outer cylinder cast steel piece. BACKGROUND

[0002] The steam turbine outer cylinder cast steel piece has the problem of uneven blank weight in the manufacturing process, which seriously affects the axial positioning, the determination of the high-low wheel center and the connection of all the pipes of the cylinder body. The purpose of the steam cylinder load distribution experiment is to identify the distortion of the cast steel piece, correct the support height position of the processing, thereby reducing the geometric deviation and avoiding the uneven settlement and uneven expansion of the unit caused by the asymmetry and uneven weight of the cylinder, thereby affecting the long-period safe operation of the unit.

[0003] The conventional method for the load distribution test of the steam turbine outer cylinder cast steel piece in the prior art divides the cylinder body support part into two groups of front end and rear end, sets four gasket positions, sets a hydraulic jack below each gasket position and installs a dial gauge above each gasket position to measure the jacking value, jacks up a single jack, records the values of the left and right dial gauges of each group, inserts a gasket group on the gasket on the side with a smaller load value, and repeatedly tests until the loads on the left and right sides are balanced. The method needs to be repeatedly jacked up at the four gasket positions one by one, and the gasket group needs to be adjusted, which consumes a large amount of time, has low test efficiency, has large measurement error and is difficult to achieve accurate balancing. SUMMARY

[0004] In order to overcome the problems of the prior art, such as the low test efficiency, large measurement error and the like caused by the repeated jacking up of the four gasket positions of the cast piece one by one and the adjustment of the gasket group, the application provides a novel cast piece load distribution test method, and the specific technical scheme is as follows.

[0005] A cast piece load distribution test method, the cast piece comprising a first end part and a second end part, the method comprising the following steps:

[0006] Step 01, placing the cast piece on a processing platform, determining a support point, a detection point and a jacking point on the first end part and the second end part of the cast piece respectively, the jacking point being close to the support point, and the detection point being arranged at the plane of the upper surface of the first end part or the second end part.

[0007] Step 02, arranging a gasket below each support point, and each gasket being used for supporting the cast piece.

[0008] Step 03, the first end load distribution test: set up dial gauges at the detection points on both sides of the first end and set them to zero; and set up jacking assemblies under the jacking points on both sides; start the jacking assemblies to jack the first end away from the cushion block, and continue jacking until a set value is reached; record the display values of the two dial gauges and calculate the difference value every time a set value is jacked, if the difference value of n+1 times minus the difference value of n times is less than or equal to the standard cumulative difference value, then the first end is in a stable state at this time, stop jacking and make the jacking assemblies descend until the first end falls onto the cushion block; wherein n is the number of jacking times, n is greater than or equal to 1.

[0009] Step 04, the second end load distribution test: use the process method of step 03 to conduct the jacking test of the second end and record the display values of the dial gauges.

[0010] Step 05, compare the display values of the dial gauges obtained in step 03 with the display values of the dial gauges obtained in step 04, if the display values of the same side of the casting are larger, the load distribution test is ended; if the display values of different sides of the casting are larger, insert a gasket group with the same thickness and display value between the casting and the cushion block at the support point corresponding to the detection point with larger display value.

[0011] Preferably, it further comprises step 06, complete load distribution test: for the end of the casting which has no gasket group inserted in step 05, use the process method of step 03 to conduct the load distribution test, after reaching the stable state, compare the difference values of the dial gauges on both sides, if the difference value is greater than the standard difference value, then insert a gasket group with the same thickness and display value between the casting and the cushion block at the support point corresponding to the detection point with larger display value; if the difference value is less than or equal to the standard difference value, then end the load distribution test; then for the end of the casting which is far away from the end of the casting which has no gasket group inserted in step 05, use the process method of step 03 to conduct the load distribution test, after reaching the stable state, compare the difference values of the dial gauges on both sides, if the difference value is greater than the standard difference value, then insert a gasket group with the same thickness and display value between the casting and the cushion block at the support point corresponding to the detection point with larger display value; if the difference value is less than or equal to the standard difference value, then end the load distribution test.

[0012] Preferably, in step 03, the jacking parameters of the jacking assemblies set under the jacking points on both sides of the first end are all the same during the jacking process; wherein the jacking assemblies are preferably hydraulic jacks, and the hydraulic jacks jacked simultaneously have the same parameters and the same length of hydraulic cable during the jacking process, so as to ensure that the pressure of the hydraulic jacks is completely equal, and the heights of the two sides of the end of the jacked casting are the same.

[0013] Preferably, the standard cumulative difference value is 0.05mm; due to the limitation of the measuring precision, when the standard cumulative difference value is less than or equal to 0.05mm, the difference value can be caused by errors, and the change of the reading difference of the left and right dial gauges can be ignored, and it can be considered that the reading difference of the left and right dial gauges is constant, and the state is stable; when the standard cumulative difference value is greater than 0.05mm, in addition to the change caused by errors, the change of the reading difference of the left and right dial gauges cannot be ignored, and the state is unstable.

[0014] Preferably, the flatness of the detection point position is less than or equal to 0.2mm; due to the measuring precision and system errors, 0.2mm is the maximum platform flatness deviation that can be accepted in subsequent processing, if the flatness is less than 0.2mm, the platform flatness deviation can be ignored, and if the flatness exceeds 0.2mm, the platform flatness error will significantly affect the measurement result.

[0015] Preferably, the standard difference value is 0.05mm; due to the limitation of the measuring precision, when the standard difference value is less than or equal to 0.05mm, it indicates that the readings of the left and right dial gauges are basically the same, and the difference value can be caused by errors, and at this time, it can be considered that the left and right are balanced, and the shim set does not need to be applied; when the standard difference value is greater than 0.05mm, it indicates that the reading difference of the left and right dial gauges is large, and the difference value is caused by errors and cylinder imbalance, and at this time, it is considered that the left and right are unbalanced, and the shim set needs to be applied.

[0016] The present application provides a kind of test method of casting load distribution, first, casting is placed on processing platform, then according to the structure of casting determines support point, detection point, jacking point, wherein support point is the bottom of four corners of casting, i.e. determine the position that casting can be stably supported;Jacking point is close to support point, i.e. the position point of jacking assembly jacking casting;Detection point is arranged at the plane of the upper surface of the four corner end of the casting close to jacking point, for setting dial gauge at it to detect the actual jacking amount there, compare and measure the state of casting load distribution by the measured value of each dial gauge, determine subsequent test process.After the whole process test is completed, i.e. after complete load test is completed, with the position of the lowest value of the dial gauge of casting as reference position, use processing machine tool to mark a horizontal line on the side of detection point position, and record the test data in test process and the thickness of each position shim set in test report, for customer use.

[0017] The test method of the present application is used to test the two sides of the front and rear ends of the casting simultaneously, which realizes the function of simultaneously measuring the jacking amount of the two sides at the front end or the rear end of the casting, without recording the absolute reading of the pressure gauge of the jacking piece, but setting the shim set through the difference value of the dial gauge display value, to realize the functions of high efficiency, rapidness and accuracy. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 isometric view of the casting in the example;

[0019] Figure 2 left view of the casting in the example;

[0020] Figure 3 rear view of the casting in the example;

[0021] Figure 4 right view of the casting in the example;

[0022] 100 - first end; 200 - second end; 300 - pad; 400 - dial gauge; 500 - jacking assembly. DETAILED DESCRIPTION

[0023] In order to make the present application more comprehensively understood, the following will describe the present application in conjunction with specific embodiments and relevant drawings. The drawings show the preferred embodiments of the present application. However, the present application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0024] In the description of the present application, it should be understood that the terms "first" and "second" are only for the purpose of description and cannot be understood as indicating or implying relative importance or implicitly indicating the number or order of the indicated technical features.

[0025] The present embodiment takes a steam turbine outer cylinder casting as an example. Since the casting is asymmetric and the weight is unbalanced, after pouring is completed, a load distribution test needs to be performed. The two ends in the axial direction of the casting are divided into a first end 100 and a second end 200. For details, refer to the drawings. Figures 1-4 The specific distribution test method steps are as follows:

[0026] Step 01, place the casting on the machining platform, and determine the support point, detection point, and jacking point at the first end 100 and the second end 200 of the casting. The jacking point is close to the support point, and the detection point is set at the plane of the upper surface of the first end 100 or the second end 200. The detection point can be set on the upper plane or measurable plane of the flange of the casting.

[0027] Step 02, set a pad 300 under each support point, and each pad 300 is used to support the casting. The height difference of each pad 300 is less than or equal to 0.2 mm, which ensures stable support of the casting while ensuring that the bottom surface of the casting is at the same horizontal plane, thereby ensuring the accuracy of the distribution test.

[0028] Step 03, load distribution test of the first end portion 100: set the dial gauges 400 at the detection points on both sides of the first end portion 100 and set them to zero; and set the jacking assemblies 500 under the jacking points on both sides; start the jacking assemblies 500 to jack up the first end portion 100 to separate it from the pads 300, continue jacking up the jacking assemblies 500 by a set value; record the display values of the two dial gauges 400 and calculate the difference value every time a set value is jacked up, if the difference value of the n+1 time minus the difference value of the n time Δ is less than or equal to the standard cumulative difference value, then the first end portion 100 is in a stable state at this time, stop jacking up and make the jacking assemblies 500 descend until the first end portion 100 falls onto the pads 300; wherein n is the number of jacking times, n is greater than or equal to 1. Specifically, the minimum distance of jacking up is 0.1 mm, the maximum distance is 0.5 mm, and the number of jacking times is greater than or equal to 3 times, until the difference value Δ of three consecutive jacking times is less than or equal to the standard cumulative difference value, at which time it is considered to be in a stable state.

[0029] After a stable state is formed, a jacking up check of stability of 1.0 mm is performed again, the difference between the indication difference of this time and the indication difference of the previous three consecutive jacking times is still less than or equal to the standard cumulative difference value, and the indication difference of this time is considered to be a stable value.

[0030] Step 04, load distribution test of the second end portion 200: use the process method of step 03 to perform jacking test of the second end portion 200 and record the display values of the dial gauges 400.

[0031] Step 05, compare the display values of the dial gauges 400 obtained in step 03 with the display values of the dial gauges 400 obtained in step 04, if the display values of the same side of the casting are larger, the load distribution test is ended; if the display values of different sides of the casting are larger, insert a gasket group with the same thickness and display value between the casting and the pads 300 at the support points corresponding to the detection points with larger display values.

[0032] Step 06, complete load distribution test: at the end portion of the casting which is not inserted with the gasket group in step 05, use the process method of step 03 to perform load distribution test, after reaching a stable state, compare the difference values of the dial gauges 400 on both sides, if the difference value is greater than the standard difference value, then insert a gasket group with the same thickness and display value between the casting and the pads 300 at the support points corresponding to the detection points with larger display values; if the difference value is less than or equal to the standard difference value, then end the load distribution test; then at the end portion away from the end portion of the casting which is not inserted with the gasket group in step 05, use the process method of step 03 to perform load distribution test, after reaching a stable state, compare the difference values of the dial gauges 400 on both sides, if the difference value is greater than the standard difference value, then insert a gasket group with the same thickness and display value between the casting and the pads 300 at the support points corresponding to the detection points with larger display values; if the difference value is less than or equal to the standard difference value, then end the load distribution test.

[0033] Specifically, each dial gauge 400 needs to be zeroed before each step, and the detection points are as far away from the center axis of the casting as possible and perpendicular to the center axis.

[0034] In step 03, the jacking assemblies 500 arranged below the jacking points on both sides of the first end 100 have the same jacking parameters during the jacking process; preferably, the jacking assemblies 500 are hydraulic jacks, and the hydraulic cables of the jacking assemblies 500 have the same length, so that the pressure of the hydraulic jacks is completely equal, and the heights of the two sides of the end of the casting are the same.

[0035] It should be noted that due to the limitation of the accuracy of the measuring tool, the standard cumulative difference value is determined to be 0.05 mm; when the standard cumulative difference value is less than or equal to 0.05 mm, the difference value may be caused by error, and the change in the reading difference of the left and right dial gauges 400 can be ignored, and it can be considered that the reading difference of the left and right dial gauges 400 is constant, and the state is stable; when the standard cumulative difference value is greater than 0.05 mm, in addition to the change caused by error, the change in the reading difference of the left and right dial gauges 400 cannot be ignored, and the state is unstable.

[0036] Due to the limitation of the accuracy of the measuring tool, the standard difference value is determined to be 0.05 mm; when the standard difference value is less than or equal to 0.05 mm, it indicates that the readings of the left and right dial gauges 400 are basically the same, and the difference value may be caused by error, and at this time it can be considered that the left and right are balanced, and the shim set does not need to be applied; when the standard difference value is greater than 0.05 mm, it indicates that the reading difference of the left and right dial gauges 400 is large, and the difference value is caused by error and cylinder imbalance, and at this time it is considered that the left and right are unbalanced, and the shim set needs to be applied.

[0037] Due to the limitation of the accuracy of the measuring tool and system error, the flatness of the detection point position is ensured to be less than or equal to 0.2 mm; 0.2 mm is the maximum platform flatness deviation that can be accepted in subsequent processing, if the flatness is less than 0.2 mm, the platform flatness deviation can be ignored, and if the flatness exceeds 0.2 mm, the platform flatness error will significantly affect the measurement result.

[0038] After the overall completion of the casting load distribution test, the position with the lowest value displayed by the casting dial gauge 400 is taken as the reference position, a horizontal line is marked on the side of the detection point position using a machining machine tool, and the test data during the test and the thickness of each position shim set are recorded in the test report for the customer to use.

[0039] Any combination of the technical features in the above-described embodiments can be made, and for the sake of brevity, not all possible combinations are described, however, as long as the combination of the technical features does not exist in contradiction, it shall be considered within the scope of the present disclosure.

[0040] The above-described embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it shall not be understood as a limitation on the patent scope of the present application. It shall be pointed out that, for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, and these shall be within the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims.

Claims

1. A method of cast load distribution testing, characterized by, The cast includes a first end and a second end, and the method includes the following steps: Step 01, determining a support point, a detection point and a jacking point at the first end and the second end of the cast respectively, the jacking point being close to the support point, and the detection point being arranged at the plane of the upper surface of the first end or the second end; Step 02, arranging a pad under each support point, each pad being used to support the cast; Step 03, the first end load distribution test: arranging a dial gauge at each detection point on both sides of the first end and setting zero, and arranging a jacking assembly under each jacking point on both sides; starting the jacking assembly to jack up and separate the first end from the pad, and continuing to jack up by a set value; recording the display values of the two dial gauges and calculating the difference value every time the set value is jacked up, if the difference value of n+1 times minus the difference value of n times is less than or equal to the standard cumulative difference value, then the first end is in a stable state at this time, stop jacking up and make the jacking assembly descend until the first end falls onto the pad; wherein n is the number of jacking up, and n is greater than or equal to 1; Step 04, the second end load distribution test: using the process method of step 03 to carry out the jacking test of the second end and record the display values of the dial gauges; Step 05, comparing the display values of the dial gauges obtained in step 03 with the display values of the dial gauges obtained in step 04, if the display values of the same side of the cast are larger, the load distribution test is ended; if the display values of different sides of the cast are larger, a gasket group with the same thickness as the display value is inserted between the cast and the pad at the support point corresponding to the detection point with larger display value; Step 06, complete load distribution test: at the end of the cast without inserting the gasket group in step 05, using the process method of step 03 to carry out the load distribution test, after reaching the stable state, comparing the difference values of the dial gauges on both sides, if the difference value is greater than the standard difference value, then a gasket group with the same thickness as the display value is inserted between the cast and the pad at the support point corresponding to the detection point with larger display value; if the difference value is less than or equal to the standard difference value, the load distribution test is ended; then at the end away from the end of the cast without inserting the gasket group in step 05, using the process method of step 03 to carry out the load distribution test, after reaching the stable state, comparing the difference values of the dial gauges on both sides, if the difference value is greater than the standard difference value, then a gasket group with the same thickness as the display value is inserted between the cast and the pad at the support point corresponding to the detection point with larger display value; if the difference value is less than or equal to the standard difference value, the load distribution test is ended. In step 03, the jacking parameters of the jacking assemblies arranged under the jacking points on both sides of the first end are the same during the jacking process.

2. The cast loading distribution test method of claim 1, wherein, The standard cumulative difference value is 0.05 mm.

3. The cast loading distribution test method of claim 1, wherein The flatness of the detection point position is less than or equal to 0.2 mm.

4. The cast loading distribution test method of claim 1, wherein The standard difference value is 0.05 mm.

5. The cast loading distribution test method of claim 1, wherein ​

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