JP6162477B2 - Thermal erosion tester - Google Patents

Description

  The present invention relates to a thermal erosion tester.

  A bonded sand core and sand mold comprising a mixture of sand, clay or chemical binder, and optionally a refractory coating is an important part of the metal casting technology. Combined sand cores and sand molds, or the nature of green cores and green sand molds, to control the quality of metal castings formed with these sand cores and sand molds when contacted with molten metal. Is important to. The friability of the sand mixture is one factor that affects the quality of castings with bonded sand cores or sand molds.

  Crushability is the ability of a solid material to break into smaller pieces, and the crushability of a sand mixture is considered a measure of the abrasion resistance of sand. Sand mixtures that are prone to crushing are sand mixtures that cannot withstand the erosive flow of molten metal during casting. A sand mixture that is prone to crushing causes sand particles to flow into the flowing molten stream, and loose sand causes further erosion and inclusion defects. As the friability of the sand mixture used in the mold increases, the ability to die deep cavities decreases and sand from the upper half of the mold falls into the lower half of the mold, causing defects in casting. If there is too much inflow of core sand or fresh sand and fresh adhesive during the mixing process, the mold sand mixture becomes very friable. New adhesives require several passes through the mixer before their properties are manifested.

  Crushability is inversely proportional to moldability. The lower the moldability, the higher the crushability. Some types of sand are very moisture sensitive to their formability, depending on their composition and moisture and / or clay content.

  In the current standard AFS friability test, two standard AFS sand samples (5 cm (2 inches) diameter × 2 cm high cylindrical shape samples) are 18 cm (7 inches) in diameter. By placing them side by side in a cylindrical screen and then rotating the screen for 1 minute, the samples rotate and rub against each other. The test is usually performed immediately after sample preparation, but may be tested after various air drying intervals. As the sample rotates, the sand polished from the surface is collected in the pan. The weight loss is usually expressed as the weight loss of the sand sample divided by the original starting weight (of both samples) and multiplied by 100 to give "percentage friability". A study by the AFS Green Sand Test Committee suggests that a friability level of less than 10% is generally satisfactory for the use of molds and cores. When the friability of the sand mixture is greater than 10%, the mold that mixes the sand mixture is prone to erosion and inclusion type defects when used with molten metal.

  Currently used AFS friability tests are performed at room temperature and involve rubbing two room temperature sand samples. Current friability tests also do not take into account the pressure generated when pouring molten metal from a certain height. The crushability test currently used also has no mechanism for expressing the ratio of metal to sand. Thus, the current test of rubbing two samples does not accurately reflect what happens in the actual casting situation.

  One embodiment of the present invention is an apparatus for performing a thermal erosion test on a sand sample, and the apparatus includes a sample holder that supports the sand sample. A rotating heating element is placed under the sample holder and is operatively rotated by a motor. The rotating heating element is configured to contact the sample through the opening in the sample holder while being operatively rotated by the motor. A funnel is placed under the sample holder and is configured to capture loose sand that has been polished from the sample by contact of the rotating heating element with the sample. The metering member is configured to detect the weight of loose sand.

  Another aspect of the present invention is an apparatus for performing a thermal erosion test on a sand sample, the apparatus comprising a heating element. The motor is operatively engaged with the heating element and rotates the heating element when the heating element contacts the sand sample. A member is provided for collecting sand that has been polished and loosened from the sand sample by rotation of the heating element.

  Another aspect of the present invention is a method for performing a friability test on a sand sample. The method includes supporting a sand sample above the heating element. The sand sample has a tapered hole inside. The heating element and the sand sample are brought into contact with the heating element adjacent to the tapered hole of the sand sample. The heating element is rotated to a predetermined degree, and the sand that has been polished and loosened is collected from the sand sample, and the loose sand is measured.

It is an upper perspective view of an embodiment of a thermal erosion tester. FIG. 2 is a top perspective view of the thermal erosion tester shown in FIG. 1 in place for performing a thermal erosion test. It is a top perspective view of the sand sample production | generation base part which is the state in which the guide part was installed on the top. It is an upper perspective view of the sand sample production | generation base part which is the state in which the guide part and the cylindrical tube were installed on the top. FIG. 3 is a top perspective view of a sand sample generating base with a guide and a cylindrical tube installed on top and a pusher used to form sand. It is an upper perspective view of the sand squeezer which shape | molds the sand of a sand sample production | generation base. It is the schematic which shows collection | recovery of the data by the thermal erosion test machine shown by FIG.

  A preferred embodiment of a thermal erosion tester (“TET”) 10 for testing the friability of a sand sample 12 shown in FIGS. 1 and 1A includes a cylindrical tube 14 holding a sand sample 12, a tubular sample holder 16, and A rotating heating element 18 to which a variable speed motor 20 for controlling rotation is attached, a funnel 22 for capturing loose sand 26 polished from the sand sample 12, and loosened by polishing from the sand sample 12 during the thermal erosion test. And a measuring member 24 for measuring the sand 26.

  As best shown in FIG. 1, the sand sample 12 preferably comprises hollow cylindrical sand. As used herein, “sand” includes, but is not limited to, sand, a mixture of sand and binder, or a mixture of sand and binder having a refractory coating on the surface. Accordingly, a “sand sample” includes a sample formed from any of the aforementioned types of sand. The sand sample 12 is made using a generally disc-shaped base 30 having a raised edge 32 extending upward around the periphery. As shown in the embodiment shown in FIG. 2, the cylindrical guide portion 34 having a smaller diameter than the base portion 30 fits in the central portion of the base portion 30 and extends upward from the central portion. When assembled to the base 30, the end portion 33 of the cylindrical guide 34 disposed adjacent to the base 30 is tapered. The tapered portion is preferably about 2 inches of the length of the cylindrical guide portion 34. As shown in the embodiment shown in FIG. 3, a hollow cylindrical tube 14, preferably an AFS standard 5 cm (2 inch) inner diameter tube, is then placed over the base 30 and in place by a raised edge 32. An opening 36 is provided between the cylindrical guide 34 and the hollow cylindrical tube 14. Sufficient sand was then weighed and poured into the opening 36 to form a sample having a tapered hole 37 in the center and a height of 5 cm (2 inches) and a diameter of 5 cm (2 inches). Can be removed.

  As shown in the embodiment shown in FIG. 4, a pusher 38 is placed around the cylindrical guide 34 and pushed down manually to pack the sand into the opening 36 and for use with an automatic sand squeezer 40. Prepare the sample. As shown in the embodiment shown in FIG. 5, the automatic sand squeezer 40 is activated until a pressure of about 140 psi is applied to the sand sample 12, and this pressure is maintained for about 3 seconds. After the sand sample 12 is formed, the base 30, the cylindrical guide 34, and the pusher 38 are removed from the sand sample 12, and the sand sample 12 having a tapered hole 37 passing through the center remains in the cylindrical tube 14.

  As shown in the embodiment of the TET 10 shown in FIGS. 1 and 1A, the sand sample 12 and the cylindrical tube 14 are placed on the tubular sample holder 16 of the thermal erosion tester 10 during operation. As shown in FIGS. 1 and 1A, the tubular sample holder 16 has an opening 41 that allows the rotary heating element 18 to pass upward into the tapered hole 37 of the sand sample 12. to enable. The rotating heating element 18 is preferably shaped to fit the tapered hole 37 of the sand sample 12 so as to contact the sand sample 12 along the entire length of the tapered hole 37 passing through its center. . For example, the shape of the rotary heating element 18 can be generally conical or frustoconical. The rotating heating element 18 preferably has a textured surface 43 that contacts the sand sample 12 and polishes the sand sample 12. One example of such a textured surface 43 is a longitudinal rib pattern. When used for casting, the rotary heating element 18 is heated to a predetermined temperature so as to coincide with the temperature of the molten metal poured into the sand mold. The tubular sample holder 16 can be lowered above the rotating heating element 18 such that the rotating heating element 18 is in contact with the rotating heating element 18 with the rotating heating element 18 in the hollow portion of the sand sample 12. Alternatively, the rotating heating element 18 can be lifted into contact with the sand sample 12. The rotary heating element 18 can be lifted using, for example, a hydraulic member 42. The rotating heating element 18 and the sand sample 12 preferably contact slowly so as to avoid the loss of the sand sample 12 as a result of contact between the sand sample 12 and the rotating heating element 18 or as a result of the high speed movement of the sand sample 12. Be made.

  The sand sample 12 is placed on the rotating heating element 18 and held on the rotating heating element by the weight of the sand sample itself, so that a predetermined pressure can be applied to the sand sample 12 by the rotating heating element 18 or the sand. The sample 12 can be fixed in place by coming into contact with the rotating heating element 18. The rotary heating element 18 can be rotated at a variable speed by the transmission motor 20. Next, the rotary heating element 18 is rotated by about 1/4 rotation to about 1 rotation, and during this rotation, the rotary heating element 18 rubs against the sand sample 12, and some of the sand loosens and erodes. Preferably, sufficient rotation is provided to produce measurable and reproducible results. Further, the rotational speed is preferably selected to increase sand loss reproducibility using the same type of sand sample 12.

  A funnel 22 is placed under the rotating heating element 18 so that the polished and loose sand 26 is trapped in the funnel 22 as it falls from the sand sample 12. The funnel 22 is preferably a glass material or a plastic material. The measuring member 24 measures the mass of sand collected in the funnel 22. The weight and appearance of the polished and loose sand 26 can be monitored throughout the duration of the thermal erosion test.

  During or after the thermal erosion test, the test worker can observe the shade of the sand. High temperatures affect the clay content or chemical binder in the sand and cause wear. In the sand sample 12 that is polished at room temperature, the sand to be polished has a charcoal black color, which is the same color as the sand used in the sand sample as it exits the mixer. When sand sample 12 is tested at 300 ° C., the polished sand is gray, and when sand sample 12 is tested at 700 ° C., the polished sand is light gray.

  As shown in FIG. 6, TET 10 measures the bulk surface wear of sand sample 12 at high temperatures. The TET 10 includes a sensor 50 that measures the elapsed time of the thermal erosion test, a sensor 52 that measures the temperature of the rotary heating element 18, and a sensor 54 that measures the weight of sand polished from the sand sample 12. All sensors preferably take measurements in real time. Data collected by the sensors 50, 52, 54 is transmitted to the data collection system 56. The data collection system 56 continuously records the data collected by these sensors 50, 52, 54, optionally throughout the duration of the thermal erosion test. Preferably, as data is collected by the data collection system 56, a graphical representation 58, such as a curve, is also generated by the data collection system 56 to indicate the change in mass of the sand sample 12 as a function of time.

  The thermal erosion tester 10 described herein more closely reproduces the sand mold response when the sand mold is used to cast molten metal. The thermal erosion tester 10 allows an operator to evaluate the reaction of the sand sample 12 when heat is applied to the sand sample 12 during polishing. Because the type of sand used in the mold generally contains clay and / or other binders, heat can significantly change the friability of the sand. Clay and other binders denature and break when heated at the mold-metal contact of the mold. Therefore, measuring the friability at the expected temperature of the mold-metal contact provides a more accurate determination of the actual performance of the mold. The thermal erosion test described herein also takes into account the pressure that occurs when pouring molten metal into a mold from a certain height, and reflects the actual situation encountered when molten metal is poured into a sand mold. It also provides a more accurate representation. The results of testing various sand and binder systems can be compared to determine the relative corrosion resistance of the sample.

  One embodiment of the present invention is an apparatus that performs a thermal erosion test on a sand sample and includes a sample holder that supports the sand sample. The rotating heating element is disposed below the sample holder and is operatively rotated by a motor. The rotating heating element is configured to pass through the opening in the sample holder and contact the sand sample while being operatively rotated by the motor. A funnel is placed under the sample holder and is configured to capture loose sand that has been polished from the sand sample by contact of the rotating heating element with the sand sample. The metering member is configured to detect the weight of loose sand.

  Another aspect of the present invention is an apparatus that performs a thermal erosion test on a sand sample, and is an apparatus that includes a heating element. The motor is operatively engaged with the heating element and rotates the heating element when the heating element contacts the sand sample. A member is provided for collecting sand that has been polished and loosened from the sand sample by rotation of the heating element.

  Another aspect of the present invention is a method for performing a friability test on a sand sample. The method includes supporting a sand sample on a heating element. The sand sample has a tapered hole inside. The heating element and the sand sample are brought into contact with the heating element adjacent to the tapered hole of the sand sample. The heating element is rotated to a predetermined degree, and the sand that has been polished and loosened is collected from the sand sample, and the loose sand is measured.

  In the foregoing part of the specification, specific embodiments of the invention have been described. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present invention as set forth in the claims below. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present invention. . Benefits, benefits, solutions to problems, and every element that can produce or make any benefit, advantage, or solution important and necessary in some or all claims That is, it should not be interpreted as an essential feature or element. The invention is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued.

Claims (19)

An apparatus for performing a thermal erosion test on a sand sample,
A sample holder for supporting the sand sample;
A rotating heating element disposed under the sample holder and operatively rotated by a motor, the rotating heating element being opened in the sample holder while being operatively rotated by the motor; A rotating heating element configured to penetrate the portion and contact the sand sample;
A funnel disposed below the sample holder, the funnel configured to capture loose sand polished from the sand sample by contact of the rotating heating element with the sand sample;
A metering member configured to detect the weight of the loose sand.   The apparatus of claim 1, wherein the motor that operatively rotates the rotating heating element is a variable speed motor.   The apparatus according to claim 1, wherein the rotary heating element further has a contact surface in contact with the sand sample, and the contact surface is textured.   The apparatus of claim 3, wherein the pattern of contact surfaces includes raised longitudinal ribs.   The metering member is configured to measure the weight of the loose sand at least twice during the thermal erosion test and substantially continuously during the thermal erosion test and send data to a data collection system. The apparatus of claim 1.   The apparatus according to claim 5, wherein the rotating heating element is configured to press the sand sample with a predetermined pressure through an opening in the sample holder.   The apparatus of claim 1, wherein the funnel is formed from a transparent material. An apparatus for performing a thermal erosion test on a sand sample,
A heating element;
A motor that operably engages the heating element and rotates the heating element when the heating element contacts the sand sample;
A sand sample support member for supporting the sand sample on the heating element;
A member that collects loose sand polished from the sand sample by the rotation of the heating element ;
A member for detecting the weight of the loose sand ;
The heating device is configured to be lifted to contact the sand sample during the thermal erosion test and to apply a predetermined pressure to the sand sample during the thermal erosion test .   The apparatus of claim 8, wherein the heating element has a shape that is generally conical or frustoconical.   9. The apparatus of claim 8, wherein the heating element rotates from about 1/4 turn to about 1 turn while in contact with the sand sample. The apparatus of claim 10 , wherein the heating element is configured to be maintained at a temperature during the thermal erosion test that approximates a molten metal casting temperature.   9. The apparatus of claim 8, wherein the member that collects loose sand polished from the sand sample by the rotation of the heating element is a funnel, and the funnel is transparent. A method for performing a friability test on a sand sample,
Supporting the sand sample having a tapered hole therein on a heating element;
Contacting the heating element and the sand sample with the heating element adjacent to the tapered hole of the sand sample;
Rotating the heating element to a predetermined degree;
Recovering polished and loose sand from the sand sample;
Weighing said loose sand. 14. The method of claim 13 , further comprising observing the loose sand color. The method of claim 13 , wherein weighing the loose sand comprises continuously weighing the loose sand during the friability test. 16. The method of claim 15 , further comprising creating a graphical representation of the loose sand weight versus elapsed time during the friability test. Step of rotating the degree of the heating element predetermined during which the heating element is in contact with the sand sample, comprising rotating the heat generating body by about 1/4 turn to about one revolution, to claim 13 The method described. Heating the heating element to a temperature approximating the casting temperature of the molten metal;
The method of claim 13 , further comprising pressing the sand sample and the heating element together at a predetermined pressure. Providing a tapered cylindrical guide portion and hollow tube removably coupled to a generally disc-shaped base, wherein the tapered cylindrical guide portion is generally perpendicular to a central portion of the disc-shaped base; The hollow tube is disposed radially outward from the tapered cylindrical guide portion, and a space is provided between the tapered cylindrical guide portion and the hollow tube. Are defined, and
The method of claim 13 , further comprising forming sand in the space between the tapered cylindrical guide and the hollow tube to form the sand sample.

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