Method for detecting flexural strength of precision investment casting shell

Abstract

The invention relates to the field of precision investment casting shells, and provides a method for detecting the flexural strength of a precision investment casting shell, which comprises the following steps of: scraping and grinding the surface of a precision investment casting shell test block by using a scraper, fixing the shell test block on a workbench, connecting the scraper with a driving device, and driving the driving device to rotate; the driving device drives the scraper to do linear motion on the surface of the shell test block for scraping and grinding; setting acting force, stroke and speed on a scraper, enabling the scraper to scrape and grind the surface of the shell test block, and turning off a power supply after the scraping and grinding of the shell test block are finished; collecting scraps of the shell test block falling off after scraping and grinding, and weighing by using an electronic balance; the less the fallen scraps of the shell test block are, the higher the flexural strength of the surface of the shell is. According to the detection method for the flexural strength of the precision investment casting shell, the flexural strength of the precision investment casting shell can be detected, so that the molten metal scouring resistance and the scraping resistance of the shell can be detected and evaluated.

Description

Technical Field

[0001] The invention relates to the field of investment casting mold shells, and in particular to a method for detecting the flexural strength of investment casting mold shells. Background Art

[0002] In the investment casting industry, the shell preparation process is the core technology of the enterprise, and its performance directly affects the quality of the casting. At present, the shell strength is usually tested for room temperature and high temperature bending strength. Insufficient room temperature strength will cause handling cracks; insufficient high temperature strength will cause leakage during the pouring process, which will cause the shell and casting to be scrapped at the least, and the leaked metal liquid to damage the pouring equipment at the worst. Excessive shell strength will cause excessive stress and deformation of the casting after pouring, and excessive residual shell strength will make it difficult to remove the shell.

[0003] In the prior art, the strength test method for investment casting mold shell is to measure the bending strength, but there is no test and evaluation method for the mold shell's ability to resist erosion by molten metal. Especially during centrifugal casting, the erosion force of the molten metal on the surface layer of the mold shell is greater, and the ability of the mold shell surface layer to resist erosion and abrasion directly affects quality defects such as mold shell shedding and slag inclusion in castings during casting.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The purpose of the present invention is to provide a method for testing the flexural strength of a mold shell in investment casting, so as to solve the problem in the prior art that there is no method for testing and evaluating the ability of the mold shell to resist erosion by molten metal.

[0006] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0007] A method for detecting the flexural strength of an investment casting mold shell, the method comprising the following steps:

[0008] S1. Scraper setting: Use a scraper to scrape and grind the surface of the investment casting shell test block, the shell test block is fixed on a workbench, the scraper is connected to a driving device, and the driving device drives the scraper to perform linear motion on the surface of the shell test block for scraping and grinding;

[0009] S2, scraping: set the force, stroke and speed of the scraper to make the scraper scrape on the surface of the shell test block. After the scraping of the shell test block is completed, turn off the power;

[0010] S3. Weighing test: Collect the scraps of the shell test block that have been scraped off and weigh them using an electronic balance.

[0011] The method for detecting the flexural strength of an investment casting mold shell described in the present invention makes up for the deficiency of only detecting the bending strength to characterize the mold shell strength, and can realize the detection of the flexural strength of the investment casting mold shell, thereby being able to detect and evaluate the mold shell's ability to resist erosion by molten metal and its ability to resist scratching.

[0012] Furthermore, in step S2, the force on the scraper is set to 1-3N, the speed of the scraper is set to 3-10mm / s, the length of the shell test block is L, and the stroke of the scraper is set to 1 / 3*L-2 / 3*L.

[0013] Furthermore, the scraper includes a cutter head and a cutter rod, the cutter head is connected to the cutter rod, the cutter head is in direct contact with the surface of the mold shell test block, and the cutter rod is connected to the driving device.

[0014] Furthermore, the cutter head is detachably connected to the cutter rod.

[0015] Furthermore, the cutter head and the cutter rod are connected together via a connecting structure.

[0016] Furthermore, one end of the connecting structure is detachably connected to the cutter head, and the other end of the connecting structure is detachably connected to the cutter rod via a third connecting member.

[0017] Furthermore, the diameter of the cutter head is Φ1, the diameter of the cutter rod is Φ2, and Φ1 and Φ2 satisfy: Φ2 / Φ1=3.0~5.0.

[0018] Furthermore, the diameter of the connection structure is Φ3, and Φ2 and Φ3 satisfy: Φ3 / Φ2=1.25~1.50.

[0019] Furthermore, the shape of the blade head is any one of round, flat and blade tip.

[0020] Furthermore, the scraper is made of metal material.

[0021] Compared with the prior art, the method for testing the flexural strength of investment casting shells described in the present invention has the following beneficial effects:

[0022] The method for detecting the flexural strength of an investment casting mold shell described in the present invention makes up for the deficiency of only detecting the bending strength to characterize the mold shell strength by means of scraper setting, scraping and weighing detection. It can realize the detection of the flexural strength of the investment casting mold shell, thereby being able to detect and evaluate the mold shell's ability to resist erosion by molten metal and its ability to resist scraping and grinding. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1It is a schematic diagram of the front view structure of a scraper of a method for detecting the flexural strength of an investment casting shell according to Example 1 of the present invention;

[0024] Figure 2 A schematic diagram of the scraper side view structure of a method for detecting the flexural strength of an investment casting shell according to Example 1 of the present invention;

[0025] Figure 3 A schematic diagram of a top view of a scraper structure of a method for detecting the flexural strength of an investment casting shell according to Example 1 of the present invention;

[0026] Figure 4 A schematic diagram of the scraper rear view structure of a method for detecting the flexural strength of an investment casting mold shell according to Example 2 of the present invention;

[0027] Figure 5 For along Figure 4 Schematic diagram of the cross-section structure along the middle section line AA;

[0028] Figure 6 It is a schematic diagram of a method for testing the flexural strength of an investment casting mold shell according to an embodiment of the present invention.

[0029] Description of reference numerals:

[0030] 1. Cutter head; 2. Cutter rod; 20. Installation space; 3. Connection structure; 4. Third connection piece; 5. Shell test block; 6. Driving device; 61. Motor body; 62. Motor shaft; 7. Workbench; 8. Transmission device; 81. Mounting block; 82. First shaft; 83. Transmission shaft; 90. Test platform; 91. First mounting frame; 92. Second mounting frame. DETAILED DESCRIPTION

[0031] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The descriptions of "first", "second", etc. mentioned in the embodiments of the present invention are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0032] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0033] Example 1

[0034] There is a problem in the prior art that there is no detection and evaluation method for the mold shell's ability to resist erosion by molten metal.

[0035] In order to overcome the deficiencies in the prior art, the purpose of the present invention is to provide a method for detecting the flexural strength of investment casting mold shells. The present invention applies a certain force to the scraper and sets the scraper stroke and speed so that the scraper scrapes on the surface of the mold shell. The mold shell chips scraped off are weighed using an electronic balance, and the amount of mold shell chips scraped off is used to evaluate the mold shell's ability to resist erosion and scraping, that is, the mold shell flexural strength.

[0036] In order to solve the above technical problems, this embodiment proposes a method for detecting the flexural strength of an investment casting mold shell, and the method for detecting the flexural strength of an investment casting mold shell comprises the following steps:

[0037] like Figure 6 As shown, the detection method comprises the following steps:

[0038] S1. Scraper setting: Use a scraper to scrape and grind the surface of the investment casting shell test block 5. The shell test block 5 is fixed on a workbench 7 to ensure the stability of the scraping and grinding process. The scraper is connected to a driving device 6, and the driving device 6 drives the scraper to perform linear motion on the surface of the shell test block 5 for scraping and grinding;

[0039] S2, scraping: set the force, stroke and speed of the scraper so that the scraper scrapes the surface of the shell test block 5. After the scraping of the shell test block 5 is completed, turn off the power supply;

[0040] S3. Weighing test: collect the scraps of the shell test block 5 that have fallen off by scraping and grinding, and weigh them using an electronic balance; the fewer the scraps of the shell test block 5 that have fallen off, the greater the flexural strength of the shell surface, and the stronger the shell's ability to resist erosion and scraping.

[0041] The present embodiment describes a method for testing the flexural strength of an investment casting mold shell, which simulates the scouring process of the mold shell by molten metal, scrapes the surface of a mold shell test block with a scraper, and evaluates the mold shell's ability to resist scouring by weighing and detecting the amount of scraping material that falls off. This method makes up for the deficiency of only testing the bending strength when characterizing the mold shell strength, and can realize the testing of the flexural strength of an investment casting mold shell. It can also test and evaluate the mold shell's ability to resist scouring by molten metal and its ability to resist scraping.

[0042] Specifically, in this embodiment, the mold shell is a zircon sand mold shell made by investment casting.

[0043] Specifically, in step S2, the force on the scraper is set to 1-3N, the speed of the scraper is set to 3-10mm / s, the length of the shell test block 5 is L, and the stroke of the scraper is set to 1 / 3*L-2 / 3*L.

[0044] Preferably, the force on the scraper is set to 1-1.96N, and the speed of the scraper is set to 4-6mm / s.

[0045] More specifically, in this embodiment, the force on the scraper is set to 1N, the speed of the scraper is 4mm / s, the length L of the mold shell test block 5 is 40mm, the stroke of the scraper is 3 / 5*L=24mm, the reciprocating motion of the scraper is counted 5 times, and the mold shell test block 5 is fixed in front of the scraper head 1 to ensure the flatness of the surface of the mold shell test block 5.

[0046] Specifically, Figure 6 As shown, the method for detecting the flexural strength of the investment casting mold shell uses a mold shell flexural strength detection device for detection, the detection device includes a scraper, a drive device 6, a transmission device 8, a first mounting frame 91, a second mounting frame 92 and a workbench 7, the first mounting frame 91, the second mounting frame 92 and the workbench 7 are installed on a test platform 90, the drive device 6 is used to provide power for the scraper to perform scraping and grinding movements, the drive device 6 is installed on the second mounting frame 92, the transmission device 8 is installed on the first mounting frame 91, the scraper is vertically installed on the transmission device 8, the workbench 7 is installed below the transmission device 8, the mold shell test block 5 is horizontally installed on the workbench 7, and the mold shell test block 5 is installed below the scraper.

[0047] Specifically, the transmission device 8 connects the driving device 6 and the scraper to achieve linear motion of the scraper.

[0048] Specifically, Figure 6 As shown, the driving device 6 includes a motor body 61 and a motor shaft 62 . The motor body 61 is installed above the second mounting bracket 92 , and the motor shaft 62 is vertically installed below the motor body 61 .

[0049] Specifically, Figure 6 As shown, the transmission device 8 includes a mounting block 81, a first shaft 82 and a transmission shaft 83, the mounting block 81 is mounted on the first mounting frame 91, and the scraper is vertically mounted on the mounting block 81; the first shaft 82 is vertically mounted below the mounting block 81, one end of the transmission shaft 83 is connected to the motor shaft 62, the other end of the transmission shaft 83 is connected to the first shaft 82, the transmission shaft 83 is vertically arranged with the motor shaft 62, and the transmission shaft 83 is vertically arranged with the first shaft 82.

[0050] Specifically, Figure 6 As shown, an installation space 20 is provided above the knife rod 2 , and the force on the scraper can be changed by adding weights in the installation space 20 , so as to be used for scraping different shell test blocks 5 .

[0051] Specifically, Figures 1 to 3 As shown, the scraper includes a cutter head 1 and a cutter rod 2 , the cutter head 1 is connected to the cutter rod 2 , the cutter head 1 is in direct contact with the surface of the mold shell test block 5 , and the cutter rod 2 is connected to the driving device 6 .

[0052] Specifically, the cutter head 1 and the cutter rod 2 are detachably connected.

[0053] More specifically, in this embodiment, the cutter head 1 is threadedly connected to the cutter rod 2 .

[0054] Specifically, the shape of the cutter head 1 is any one of round, flat and tip-shaped.

[0055] More specifically, in this embodiment, the cutter head 1 is flat in shape.

[0056] Specifically, the scraper is made of metal material.

[0057] More specifically, in this embodiment, the scraper is made of stainless steel to ensure the stability and durability of the scraper during the scraping process.

[0058] Specifically, the diameter of the cutter head 1 is Φ1, the diameter of the cutter rod 2 is Φ2, and Φ1 and Φ2 satisfy: Φ2 / Φ1=3.0~5.0.

[0059] More specifically, in this embodiment, the diameter Φ1 of the cutter head 1 is 6 mm, the diameter Φ2 of the cutter bar 2 is 20 mm, and Φ1 and Φ2 satisfy: Φ2 / Φ1=3.3.

[0060] In this embodiment, three different shell test blocks 5 were scraped and ground, and the shell scraps dropped by the scraping were collected and weighed using an electronic balance. The results are shown in Table 1.

[0061] Table 1 Weight of each test block chip of Example 1

[0062] name Shell material weight (g) Shell flexural strength evaluation Test block 1 0.4024 most Test block 2 0.7825 Difference Test block 3 0.5470 better

[0063] It can be seen from Table 1 that the weight of the mold shell scraps of test block 2 is the largest, which is 0.7825g, the weight of the mold shell scraps of test block 3 is the second largest, which is 0.5470g, and the weight of the mold shell scraps of test block 1 is the smallest, which is 0.4024g. Therefore, the flexural strength of test block 1 is the best, the flexural strength of test block 2 is poor, and the flexural strength of test block 3 is good.

[0064] The present embodiment describes a method for testing the flexural strength of an investment casting mold shell. Firstly, this method makes up for the deficiency of only testing the bending strength to characterize the mold shell strength, and can comprehensively evaluate the mold shell's ability to resist erosion and scratching; secondly, it is suitable for testing investment casting mold shells, and provides strong support for the control and optimization of the mold shell quality.

[0065] Example 2

[0066] In this embodiment, what is different from Embodiment 1 is the detection of the investment casting yttria shell.

[0067] Specifically, in step S2, the force acting on the scraper is set to 1.96N, the speed of the scraper is set to 6mm / s, and the reciprocating motion of the scraper is counted 10 times.

[0068] Specifically, Figures 4 and 5 As shown, the cutter head 1 and the cutter rod 2 are connected together via a connecting structure 3 .

[0069] Specifically, one end of the connection structure 3 is detachably connected to the cutter head 1 , and the other end of the connection structure 3 is detachably connected to the cutter rod 2 via a third connection member 4 .

[0070] More specifically, Figure 5 As shown, one end of the connection structure 3 is sleeved and installed on the outer side of the knife rod 2, and the other end of the connection structure 3 is sleeved and installed on the outer side of the knife rod 2.

[0071] Specifically, one end of the connection structure 3 is threadedly connected to the cutter head 1 , and the other end of the connection structure 3 is detachably connected to the cutter rod 2 via a third connection member 4 .

[0072] More specifically, in this embodiment, the diameter Φ1 of the cutter head 1 is 4 mm, the diameter Φ2 of the cutter bar 2 is 20 mm, and Φ1 and Φ2 satisfy: Φ2 / Φ1=5.

[0073] Specifically, the diameter of the connection structure 3 is Φ3, and Φ2 and Φ3 satisfy: Φ3 / Φ2=1.25~1.5.

[0074] More specifically, in this embodiment, the diameter Φ3 of the connection structure 3 is 25 mm, and Φ3 and Φ2 satisfy: Φ3 / Φ2=1.25.

[0075] More specifically, in this embodiment, the shape of the cutter head 1 is circular.

[0076] In this embodiment, four different shell test blocks 5 were scraped and ground, and the shell scraps dropped by the scraping were collected and weighed using an electronic balance. The results are shown in Table 2.

[0077] Table 2 Weight of each test block chip of Example 2

[0078] name Shell material weight (g) Shell flexural strength evaluation Test block 4 0.1990 better Test block 5 0.2841 Difference Test block 6 0.0993 most Test block 7 0.1796 better

[0079] It can be seen from Table 2 that the weight of the mold shell chips of test block 4 is 0.1990g; the weight of the mold shell chips of test block 5 is the largest, which is 0.2841g; the weight of the mold shell chips of test block 6 is the least, which is 0.0993g; the weight of the mold shell chips of test block 7 is 0.1796g. Therefore, the flexural strength of test block 6 is the best, the flexural strength of test block 5 is poor, and the flexural strength of test blocks 4 and 7 is better.

[0080] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A method for testing the flexural strength of an investment casting mold shell, characterized in that: The detection method comprises the following steps: S1. scraper setting: using a scraper to scrape and grind the surface of an investment casting shell test block (5), wherein the shell test block (5) is fixed on a workbench (7), and the scraper is connected to a driving device (6), wherein the driving device (6) drives the scraper to perform linear motion on the surface of the shell test block (5) for scraping and grinding; S2, scraping: setting the force, stroke and speed of the scraper so that the scraper scrapes the surface of the shell test block (5). After the scraping of the shell test block (5) is completed, turning off the power supply; S3. Weighing test: collect the scraps of the shell test block (5) that have been scraped off, and weigh them using an electronic balance.

2. A method for detecting the flexural strength of an investment casting shell according to claim 1, characterized in that: In step S2, the force acting on the scraper is set to 1-3N, the speed of the scraper is set to 3-10mm / s, the length of the shell test block (5) is set to L, and the stroke of the scraper is set to 1 / 3*L-2 / 3*L.

3. A method for detecting the flexural strength of an investment casting shell according to claim 1 or 2, characterized in that: The scraper comprises a cutter head (1) and a cutter rod (2), the cutter head (1) being connected to the cutter rod (2), the cutter head (1) being in direct contact with the surface of the mold shell test block (5), and the cutter rod (2) being connected to the driving device (6).

4. A method for detecting the flexural strength of an investment casting shell according to claim 3, characterized in that: The cutter head (1) is detachably connected to the cutter rod (2).

5. The method for detecting the flexural strength of an investment casting shell according to claim 3, characterized in that: The cutter head (1) and the cutter rod (2) are connected together via a connecting structure (3).

6. A method for testing the flexural strength of an investment casting shell according to claim 5, characterized in that: One end of the connection structure (3) is detachably connected to the cutter head (1), and the other end of the connection structure (3) is detachably connected to the cutter rod (2) via a third connection member (4).

7. A method for testing the flexural strength of an investment casting shell according to claim 3, characterized in that: The diameter of the cutter head (1) is Φ1, the diameter of the cutter rod (2) is Φ2, and Φ1 and Φ2 satisfy: Φ2 / Φ1=3.0-5.

0.

8. A method for testing the flexural strength of an investment casting shell according to claim 7, characterized in that: The diameter of the connection structure (3) is Φ3, and Φ2 and Φ3 satisfy: Φ3 / Φ2=1.25-1.

50.

9. A method for testing the flexural strength of an investment casting shell according to claim 8, characterized in that: The shape of the blade head (1) is any one of a round shape, a flat shape and a blade tip shape.

10. A method for testing the flexural strength of investment casting shell according to claim 1, characterized in that: The scraper is made of metal material.

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