TWI580962B - Apparatus for performing thermal erosion test on a sand specimen and method of performing friability test on a sand specimen - Google Patents

Description

Device for performing thermal erosion test on sand sample and method for performing fragility test on sand sample

This invention relates to a thermal erosion tester.

Combined cores and molds comprising a mixture of sand, clay or chemical tethering agents, and optional refractory coatings are an important part of metal casting technology. When placed in contact with the molten metal, the performance of the bonded core and the mold or wet sand core and mold is important to control the quality of the metal castings formed using these cores and molds. The friability of the sand mixture is an influential factor in the quality of the casting using a bonded core or mold.

Fragility is the ability of a solid material to be reduced to smaller pieces, and the friability of a sand mixture is considered to be one of the sand's resistance to scratching. The fragile sand mixture is a sand mixture that cannot withstand the erosive flow of molten metal during casting. The fragile sand mixture loses sand particles to the flowing melt stream, and the loose sand causes additional erosion and inclusion defects. As the friability of the sand mixture used in a mold increases, the ability to pull out the deep pocket is reduced, and the sand from the top half of the mold falls into the bottom half of the mold and causes one in the casting. defect. If an influent of the sand or new sand is too high, the mold sand mixture becomes very brittle and combines during the mixing process. The new combination requires several passes through a mixer before it develops its properties.

Fragility is inversely related to compactness. The lower the compactness, the higher the friability. Some mold sands are determined by their composition and moisture and/or clay content. The stability is extremely moisture sensitive.

In today's standard AFS Fragility Test, two standard AFS sand samples (cylindrical specimens, 2 吋 diameter × 2 吋 high) are placed side by side in a 7 吋 diameter cylindrical screen, and then the screen is rotated The sample was rotated for one minute and rubbed against each other. The test is usually carried out immediately after the preparation of the sample, but can be tested after different air drying intervals. As the sample is rotated, the sand scraped from the surface is collected in a basin. The weight loss is usually expressed by dividing the weight loss of the sand sample by the original starting weight (of the two samples) and multiplying by 100 to produce "percent fragility". The results of the AFS Wet Sand Test Association show that less than 10% of the fragility level is generally satisfactory for use in molds and cores. If the friability of the sand mixture is greater than 10%, a mold incorporating the sand mixture will be eroded and contain inclusion defects when used in conjunction with the molten metal.

The AFS Fragility Test currently in use is carried out at room temperature and involves rubbing two room temperature sand samples together. The current friability test does not take into account the pressure generated when the metal is highly dumped. There is also no mechanism or variation in the friability test currently used to represent the ratio of metal to sand. Therefore, the tests that now rubbed the two specimens together did not accurately depict what would happen in a real world casting situation.

One aspect of the invention includes a device for performing a thermal erosion test on a sand sample comprising a sample holder for supporting a sand sample. A rotating heat receiving element is disposed below the sample holding member and operatively rotated by a motor. The rotating heated element is adapted to extend through an opening in the sample holder to contact the sample as the rotating heated element is operatively rotated by the motor. A funnel is disposed below the sample holder, wherein the funnel is adapted to capture loose sand that is scraped from the sample by contact of the rotating heated element with the sample. A weighing component is adapted to detect the weight of loose sand. The weighing element is adapted to measure the weight of the loose sand at least twice during a thermal erosion test, or preferably continuously measuring the weight of the loose sand Amount and transfer the data to a data acquisition system.

Another aspect of the invention includes a device for performing a thermal erosion test on a sand sample comprising a heated element. A motor is operatively coupled to the heated element and rotates the heated element when the heated element is brought into contact with the sand sample. A member is provided to collect loose sand that has been sanded from the sand sample by rotation of the heated element.

Another aspect of the invention includes a method for performing a friability test on a sand sample. The method includes the step of supporting a sand sample over a heated element. The sand sample has a push hole. The heated element and the sand sample are led to contact the heated element adjacent to the push-out hole of the sand sample. The heated element is rotated by a predetermined amount, any loose sand system that is ground from the sand sample is collected, and the loose sand system is weighed.

10‧‧‧ Thermal Erosion Tester (TET)

12‧‧‧ sand sample

14‧‧‧Cylindrical tube

16‧‧‧tube sample holder

18‧‧‧Rotating heating elements

20‧‧‧ Variable speed motor

22‧‧‧ funnel

24‧‧‧Weighing components

26‧‧‧Loose sand

30‧‧‧Generally dished substrate

32‧‧‧High edge

33‧‧‧End portion of cylindrical guide 34

34‧‧‧Cylindrical guides

36‧‧‧ openings

37‧‧‧Pushing holes

38‧‧‧Parts

40‧‧‧Automatic sand extruder

41‧‧‧ openings

42‧‧‧Hydraulic components

43‧‧‧Texture surface

50, 52, 54‧‧‧ sensor

56‧‧‧Information Acquisition System

1 is a top perspective view of an embodiment of a thermal erosion tester; FIG. 1A is a top perspective view of the thermal erosion tester of FIG. 1 in a position where a thermal erosion test can be performed; FIG. 2 is a sand sample a top perspective view of the substrate is provided with a guide member; FIG. 3 is a top perspective view of the sand sample generating substrate, which is provided with a guide member and a cylindrical tube; FIG. 4 is a top perspective view of the sand sample generating substrate, a guide member and a cylindrical tube are mounted thereon, and the sand is compacted by a pushing member; FIG. 5 is a top perspective view of the sand compactor for compacting sand in the sand sample generating substrate; 6 is a schematic diagram showing data collection by the thermal erosion tester shown in FIG.

As shown in Figures 1 through 1A, a preferred embodiment of a thermal erosion tester (TET) 10 for testing the fragility of a sand sample 12 comprises a cylindrical tube 14 for holding a sand sample 12 a tube of sample holder 16, a rotating heating element 18, which is fitted with a variable speed motor 20 for controlling its rotation, a funnel 22 for capturing loose sand 26 scraped from the sand sample 12, and a scale The heavy element 24 weighs the sand 26 that is sanded from the sand sample 12 during the test.

As best shown in Figure 1, the sand sample 12 preferably comprises a sand in the shape of a hollow cylinder. As used herein, "sand" includes, but is not limited to, sand, a mixture of sand and a binder, or a mixture of sand and a binder with a refractory coating thereon. To this end, the "sand sample" includes one sample formed from any of the above types of sand. The sand sample 12 is formed from a generally dished base 30 with a raised edge 32 extending upwardly around its peripheral edge. As shown in the embodiment depicted in FIG. 2, a cylindrical guide 34 having a smaller diameter than the base 30 is fitted over the central portion of the base 30 and extends upward therefrom. The end portion 33 of the cylindrical guide member 34 disposed adjacent to the base 30 when assembled with the base 30 is in a push-up shape. The push-out portion preferably extends over a length of about 2 inches of the cylindrical guide member 34. As shown in the embodiment depicted in Figure 3, a hollow cylindrical tube 14, preferably an AFS standard 2 inch inner diameter tube, is then placed over the substrate 30 and held in place by the raised edge 32. An opening 36 is left between the guide member 34 and the hollow cylindrical tube 14. A 2 inch high and 2 inch diameter sand having a push-out hole 37 in the center sufficient to generate a sample is then weighed and poured into the opening 36.

As shown in the embodiment depicted in Figure 4, a pusher 38 is placed around the guide 34 and pushed down by hand to load the sand into the opening 36 and prepare a sample for use by an automatic sand extruder 40. . As shown in the embodiment depicted in Figure 5, the automatic sand extruder 40 is activated until a pressure of about 140 psi is applied to the sand sample 12 and the pressure is maintained for about 3 seconds. Sand sample 12 pressure After that, the substrate 30, the guide 34, and the pad 38 are removed from the sand sample 12, leaving a sand sample 12 having a push-out hole 37 through the center of the cylindrical tube 14.

As shown in the TET 10 embodiment depicted in FIGS. 1 through 1A, in operation, the sand sample 12 and the cylindrical guide 14 are placed on the tube sample holder 16 of the thermal erosion tester 10. The tube sample holder 16 has an opening 41 that allows the rotating heat receiving member 18 to pass upward into the push-out hole 37 of the sample 12, as shown in Figs. 1 and 1A. The rotating heat receiving member 18 is preferably shaped to conform to the push-out hole 37 in the sand sample 12 so as to contact the sand sample 12 along the entire length of the push-pull hole 37 through its center. For example, the shape of the rotating heat receiving element 18 can be substantially conical or frustoconical. The rotating heated element 18 preferably has a textured surface 43 to contact the sand sample 12 to grind the sand sample 12. An example of a textured surface 43 is a longitudinal rib pattern. The rotating heat receiving element 18 is heated to a predetermined temperature to simulate the temperature of the molten metal to be poured into a sand mold for casting. The tube sample holder 16 can be lowered over the rotating heat receiving element 18 to bring the sand sample 12 into contact with the rotating heat receiving element 18, wherein the rotating heat receiving element 18 is located within the hollow portion of the sand sample 12. Alternatively, the rotating heat receiving element 18 can be raised to contact the sand sample 12. The rotating heat receiving element 18 can be raised, for example, by a hydraulic element 42. The rotating heat receiving element 18 and the sand sample 12 are preferably slowly brought into contact to avoid loss of the sand sample 12 due to contact between the sand sample 12 and the rotating heat receiving element 18 or due to rapid action of the sand sample 12.

The sand sample 12 is fixed to the rotating heat receiving element 18 and held there by its own weight, or the sand sample 12 can be fixed in place against the rotating heat receiving element 18, so the rotating heat receiving element 18 can be A predetermined pressure is applied to the sand sample 12. The rotating heat receiving element 18 can be rotated by the motor 20 at a shift speed. The rotating heated element 18 is then rotated from 1⁄4 to about 1 revolution, during which the rotating heated element 18 rubs against the sand sample 12, relaxing and eroding a portion of the sand. Preferably, sufficient rotation is provided to produce measurable and reproducible results. In addition, a rotational speed is preferably selected to increase the reproducibility of sand loss for the homogenous sand sample 12.

The funnel 22 is placed below the rotating heat receiving element 18, so that as the ground sand 26 falls from the sand sample 12, it is captured in the funnel 22. The funnel 22 is preferably a glass or plastic material. Weighing element 24 measures the mass of sand collected in funnel 22. The weight of the ground sand 26 can be monitored throughout the thermal erosion test time course and its appearance.

The color of the sand can be observed by the test operator during and after the test procedure. The elevated temperature affects and damages the clay content or chemical binding agent in the sand. In a wet sand sample 12 that was ground at room temperature, the sand that was ground had a coke black which was the same color as the sand used in the sand sample 12 when leaving the mixture. When the sand sample 12 was tested at 300 ° C, the sand that was ground was gray, and when the sand sample 12 was tested at 700 ° C, the sand that was ground was light gray.

As shown in Fig. 6, the TET 10 system measures the surface of the body block of the sand sample 12 at an elevated temperature. The TET 10 includes a sensor 50 to measure the elapsed time of the test, a sensor 52 to measure the temperature of the rotating heating element 18, and a sensor 54 to measure the weight of the sand sanded from the sand sample 12. Preferably, they are carried out immediately. The data collected by the sensors 50, 52, 54 is transmitted to a data acquisition system 56. The data acquisition system 56 records the data collected by these sensors 50, 52, 54 or may be continuously recorded during the test. Preferably, as the data is collected by the data acquisition system 56, a graphical representation 58 such as a curve is also generated by the data acquisition system 56, showing the change in mass of the sample 12 as a function of time.

The thermal erosion tester 10 described herein more closely replicates the response of a sand mold when used to cast molten metal. The thermal erosion tester 10 allows the operator to evaluate the reaction of the sand sample 12 while it is being heated during the sanding. Since the type of sand used in a mold generally contains clay and/or other tethering agents, heat can significantly alter the fragility of the sand. As clay and other tethering agents are heated at the mold-metal interface of a mold, they deteriorate and disintegrate. Therefore, the expected temperature measurement of the susceptibility at the mold-metal interface provides a more accurate measure of the real-world performance of the mold. The tests described herein will also generate pressure from a high level of molten metal into a mold. Force considerations also provide a more accurate representation of one of the actual environments encountered when molten metal is poured into a sand mold. The results of testing different sand and binder systems can be compared to determine the relative erosion resistance of the sample.

One aspect of the invention includes a device for performing a thermal erosion test on a sand sample comprising a sample holder for supporting a sand sample. A rotating heat receiving element is disposed below the sample holding member and operatively rotated by a motor. The rotating heated element is adapted to extend through an opening in the sample holder to contact the sample as the rotating heated element is operatively rotated by the motor. A funnel is disposed below the sample holder, wherein the funnel is adapted to capture loose sand that is scraped from the sample by contact of the rotating heated element with the sample. A weighing component is adapted to detect the weight of loose sand.

Another aspect of the invention includes a device for performing a thermal erosion test on a sand sample comprising a heated element. A motor is operatively coupled to the heated element and rotates the heated element when the heated element is brought into contact with the sand sample. A member is provided to collect loose sand that has been sanded from the sand sample by rotation of the heated element.

Another aspect of the invention includes a method for performing a friability test on a sand sample. The method includes the step of supporting a sand sample over a heated element. The sand sample has a push hole. The heated element and the sand sample are led to contact the heated element adjacent to the push-out hole of the sand sample. The heated element is rotated by a predetermined amount, any loose sand system that is ground from the sand sample is collected, and the loose sand system is weighed.

In the above description, specific embodiments of the invention have been described. However, it is to be understood by those skilled in the art that various modifications and changes can be made without departing from the scope of the invention as defined by the following claims. The specification and drawings are intended to be illustrative, and not restrictive, Advantages, advantages, solutions to problems, and possible advantages, advantages, solutions, or significant Any element is not to be construed as a critical, essential, or important feature or element of any or all of the claims. The invention is defined solely by the scope of the patent application, including any amendments made during the examination of the application and all equivalents of the scope of the claimed patents.

10‧‧‧ Thermal Erosion Tester (TET)

12‧‧‧ sand sample

14‧‧‧Cylindrical tube

16‧‧‧tube sample holder

18‧‧‧Rotating heating elements

20‧‧‧ Variable speed motor

22‧‧‧ funnel

24‧‧‧Weighing components

26‧‧‧Loose sand

37‧‧‧Pushing holes

42‧‧‧Hydraulic components

43‧‧‧Textured surface

Claims (21)

A device for performing a thermal erosion test on a sand sample, the device comprising: a sample holding member supporting the sand sample; a rotating heat receiving member disposed under the sample holding member and borrowing Operatively rotatable by a motor, wherein the rotating heat receiving element is adapted to extend through an opening in the sample holder to contact the sand sample when the rotating heat receiving element is operatively rotated by the motor; a funnel disposed under the sample holding member, wherein the funnel is adapted to capture loose sand scraped from the sand sample by contact of the rotating heat receiving element with the sand sample; and Weighing components are adapted to detect the weight of the loose sand. The device of claim 1, wherein the motor for operatively rotating the rotating heat receiving element is a variable speed motor. The device of claim 1, wherein the heated element further comprises a contact surface that becomes in contact with the sample, and wherein the contact surface is textured. The device of claim 3, wherein the texture of the contact surface comprises a raised longitudinal rib. The apparatus of claim 1, wherein the weighing element is adapted to measure the weight of the loose sand at least twice during the thermal erosion test and transmit the data to a data acquisition system. The apparatus of claim 5, wherein the weighing element is adapted to continuously measure the weight of the loose sand during the thermal erosion test. The device of claim 5, wherein the rotating heat receiving element is adapted to extend through an opening in the sample holding member against a predetermined pressure to press against the sample. The device of claim 1, wherein the funnel is formed of a transparent material. An apparatus for performing a thermal erosion test on a sand sample comprising: a heated element; a motor operatively coupled to the heated element and when the heated element is led to contact the sand sample Rotating the heated element; and a member to collect loose sand scraped from the sand sample by rotation of the heated element. The device of claim 9, wherein the heated element has a shape that is substantially conical or frustoconical. The apparatus of claim 9, further comprising: a sand sample support member supporting the sand sample above the heat receiving element; and wherein the heated element is adapted to be raised during the heat erosion test High to become in contact with the sand sample and a predetermined pressure is applied to the sand sample during the thermal erosion test. The device of claim 9, wherein the heated element is rotated from about 1⁄4 to about 1 revolution when contacted with the sand sample. The device of claim 12, wherein the heated element is adapted to be maintained at a temperature of a casting temperature of the approximately molten metal during the thermal erosion test. The device of claim 9, wherein the member for collecting loose sand scraped from the sand sample by rotation of the heat receiving element is a funnel, and wherein the funnel is transparent . A method for performing a friability test on a sand sample, comprising the steps of: supporting the sand sample above a heated element, the sand sample having a push-out hole; and leading the heated element into contact And the sand sample is adjacent to the push hole of the sand sample; Rotating the heated element by a predetermined amount; collecting any loose sand scraped from the sand sample; and weighing the loose sand. The method of claim 15, further comprising the step of observing the color of the loose sand. The method of claim 15, wherein the step of weighing the loose sand is to continuously weigh the loose sand during the fragility test. The method of claim 17, further comprising the step of preparing a graphical representation of the weight of the loose sand relative to the elapsed time during the fragility test. The method of claim 15, wherein the step of rotating the heated element by a predetermined amount comprises rotating the heated element from about 1⁄4 to about 1 revolution when the heated element contacts the sand sample. The method of claim 15, further comprising the steps of: heating the heated element to a temperature of a casting temperature of the molten metal; and pressing the sand sample and the heated element at a predetermined pressure Together. The method of claim 15, further comprising the steps of: providing a push-out cylindrical guide and a hollow tube removably coupled to a substantially dish-shaped substrate, wherein the push-like shape The cylindrical guide member extends generally vertically from a central portion of the dish-shaped base, and wherein the hollow tube is radially outwardly disposed from the push-out cylindrical guide member, wherein a space is defined in the push-out cylindrical shape Between the guide and the hollow tube; sand is compacted into the space between the push-out cylindrical guide and the hollow tube to form the sand sample.