A fluidity measuring device and method for investment casting

Abstract

The present invention provides a fluidity measuring device for investment casting, comprising: at least one mold assembly, which is arranged on a frame, each of the mold assemblies comprising an upper template and a lower template, the upper template being arranged on the lower template, the lower template being provided with a serpentine flow channel on a side close to the upper template, the upper template being provided with a flow channel opening, the flow channel opening being communicated with a pouring inlet of the serpentine flow channel; a pouring cup, which is arranged on the upper template, the pouring cup being communicated with the pouring inlet through the flow channel opening; and a heating device, which is arranged on the frame, the heating device being a constant temperature heating device. The present invention provides a fluidity measuring device and measuring device for investment casting, wherein the heating device is a water bath or a constant temperature box, thereby avoiding the fire hazard caused by using an open flame electric furnace for heating during the experiment, and the electric furnace is used to heat the material to be tested at a constant temperature, thereby making the temperature of the material to be tested easy to control and preventing energy waste.

Description

Technical Field

[0001] The invention relates to the technical field of investment casting teaching, and in particular to a fluidity measuring device and a measuring method for investment casting. Background Art

[0002] Casting is one of the basic processes of modern basic mechanical manufacturing industry. The fluidity experiment involved in the casting process is a basic experimental course for mechanical engineering majors in ordinary colleges and universities. Through fluidity experimental teaching, students can understand the concept, test methods and influencing factors of material fluidity, and have a more comprehensive understanding of the basic knowledge of engineering materials and material forming.

[0003] Traditional fluidity experimental teaching mainly focuses on the field of aluminum alloy materials. Fluidity is one of the casting properties of alloys and directly affects the filling capacity of liquid alloys. The better the fluidity of the alloy, the stronger the filling capacity, and the more it can cast clear contours, thin walls and complex castings. It is also conducive to the floating and discharge of inclusions and gases and the shrinkage compensation during the solidification process. However, alloys with poor fluidity are difficult to fill the mold cavity, and the filling capacity is reduced, which is prone to defects such as insufficient casting, cold shut, pores, and slag inclusions.

[0004] With the development of technology, investment casting has gradually grown. Investment casting, also known as precision casting or lost wax casting, is a process in which a precise fusible model is made of fusible materials (wax, etc.), and several layers of refractory coating are applied on the model. After drying and hardening, the model is formed into an integral shell, and then the shell is heated to melt the lost wax, and then baked at high temperature to form a refractory shell. Liquid metal is poured into the shell, and after cooling, a casting is formed. Compared with other casting methods, the main advantages of investment casting are as follows: the casting has high dimensional accuracy and low surface roughness, and can cast castings with complex shapes, with a general accuracy of 5-7 and a roughness of two Ra25-6.3μm; it can cast thin-walled castings and castings with very small weight, with the minimum wall thickness of investment castings up to 0.5mm and a weight as small as a few grams; it can cast castings with fine patterns, text, and castings with fine grooves and curved pores; the shape and inner cavity shape of investment castings are almost unlimited, and complex parts that are difficult to manufacture by sand casting, forging, cutting and other methods can be manufactured, and some assemblies and welded parts can be directly cast into integral parts after structural improvements, thereby reducing the weight of parts and reducing production costs; there is almost no limit on the type of casting alloy, and it is often used to cast alloy steel parts, carbon steel parts and heat-resistant alloy castings; there is no limit on the production batch, and it can be produced from single pieces to batches. With the development of investment casting technology, the types of mold materials are becoming more and more diverse, and the composition is different. Usually, mold materials are divided into high-temperature, medium-temperature and low-temperature mold materials according to their melting points. The melting point of low-temperature mold materials is about 60°C. The paraffin-stearic acid mixture currently widely used in my country is used as a low-temperature mold material. The melting point of high-temperature mold materials is higher than 120°C. The mold material composed of 50% rosin, 20% ozokerite and 30% polystyrene is a typical high-temperature mold material. The melting point of medium-temperature mold materials is between the above two types of mold materials. The currently used medium-temperature mold materials can basically be divided into two types: rosin-based and wax-based mold materials.

[0005] In the experimental practice teaching of major universities, in order to present the investment casting process to students, some fluidity measurement teaching experiments are usually carried out, and the fluidity measurement teaching experiments are realized by a fluidity measurement teaching device. The melting process of the current fluidity measurement teaching device uses an open flame electric furnace, which has a fire hazard during the measurement process. At the same time, it is difficult to control the temperature of the low-temperature mold material using an electric furnace, which can easily lead to excessive heating temperature and smoke and other exhaust gases, making it inconvenient to control the test conditions. Summary of the invention

[0006] In order to solve the above problems, the present invention provides a fluidity measuring device and method for investment casting. The heating device adopts a water bath pot or a constant temperature box, which avoids the fire hazard of using an open flame electric furnace for heating during the experiment. At the same time, the electric furnace adopts a constant temperature to heat the material to be tested, so that the temperature of the material to be tested is easy to control and energy waste is prevented.

[0007] In order to achieve the above purpose, a technical solution adopted by the present invention is:

[0008] A fluidity measuring device for investment casting comprises: at least one mold assembly, which is arranged on a frame, each of the mold assemblies comprises an upper template and a lower template, the upper template is arranged on the lower template, a serpentine runner is arranged on a side of the lower template close to the upper template, a runner opening is arranged on the upper template, and the runner opening is communicated with a pouring inlet of the serpentine runner; a pouring cup, which is arranged on the upper template, and the pouring cup is communicated with the pouring inlet through the runner opening; and a heating device, which is arranged on the frame, and the heating device is a constant temperature heating device.

[0009] Furthermore, the constant temperature heating is a water bath or a constant temperature box.

[0010] Furthermore, the mold assembly also includes a mold base and a clamping device, the mold base is arranged on the frame, and the lower mold plate is arranged on the mold base; the clamping device includes a vertical fixing rod and a transverse pressure rod, one end of the vertical fixing rod is fixed to the frame, and the other end of the vertical fixing rod is connected to one end of the transverse pressure rod, and a limiting screw is provided at the other end of the transverse pressure rod, and the limiting screw presses the upper mold plate onto the lower mold plate.

[0011] Furthermore, a threaded hole, a buffer hole and a limit hole are sequentially arranged at one end of the transverse pressure rod away from the vertical fixing rod, and the limit screw includes a threaded rod and a limit rod, and the threaded hole, the buffer hole and the limit hole are coaxially arranged, and the threaded rod and the limit rod are coaxially arranged; an internal thread is arranged on the inner wall of the threaded hole, and an external thread is arranged on the threaded rod, and the internal thread cooperates with the external thread to realize the up and down rotation of the limit screw, the diameter of the buffer hole is larger than the diameter of the threaded hole, and the diameter of the threaded hole is larger than the diameter of the limit hole, one end of the limit rod is connected to the threaded rod, and the other end of the limit rod extends out of the limit hole and abuts against the upper template.

[0012] Furthermore, the serpentine flow channel includes at least two straight flow channels and at least one semicircular flow channel, the two straight flow channels are connected through the semicircular flow channel, and the pouring inlet is connected to one end of one of the straight flow channels.

[0013] Furthermore, the upper template is a transparent material plate.

[0014] Furthermore, the transparent material plate is one of a PC plate, a plexiglass plate or a PAM plate.

[0015] The present invention also provides a method for measuring fluidity for investment casting, comprising the following steps: S10 test preparation, testing and cleaning a fluidity measuring device for investment casting; S20 configuring a material to be tested in a container, placing the container containing the material to be tested in a heating device, and heating the material to be tested according to a test temperature condition so that the material to be tested is melted to obtain a molten material; S30 pouring the melted material to be tested into a mold assembly through a pouring cup, and recording pouring result data, the pouring result data including sample surface quality, sample filling length, and flow time; and S40 waiting for the mold assembly to cool to room temperature, cleaning the material to be tested and resetting the fluidity measuring device for investment casting to complete the measurement of the material to be tested.

[0016] The above technical solution of the present invention has the following advantages compared with the prior art:

[0017] (1) In the fluidity measuring device and method for investment casting of the present invention, the heating device adopts a water bath pot or a constant temperature box, thereby avoiding the fire hazard of using an open flame electric furnace for heating during the experiment. At the same time, the electric furnace uses a constant temperature to heat the material to be tested, making the temperature of the material to be tested easy to control and preventing energy waste.

[0018] (2) The present invention provides a fluidity measuring device and method for investment casting. The upper mold plate is clamped to the lower mold plate by a clamping device, which reduces the assembly time of the mold assembly. At the same time, the clamping device is provided with a buffer hole and a limit spring to avoid damage to the mold assembly by the clamping device during the assembly of the upper and lower mold plates. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The technical solutions and beneficial effects of the present invention will be made apparent by describing in detail the specific embodiments of the present invention in conjunction with the accompanying drawings.

[0020] Figure 1 It is a structural diagram of a fluidity measuring device for investment casting according to one embodiment of the present invention;

[0021] Figure 2 Shown is a structural diagram of a mold assembly according to an embodiment of the present invention;

[0022] Figure 3 Shown is a structural diagram of a lower template according to an embodiment of the present invention;

[0023] Figure 4 The figure shows a cross-sectional view of a mold assembly and a pouring cup connected in accordance with an embodiment of the present invention;

[0024] Figure 5 Shown is a structural diagram of a clamping device according to an embodiment of the present invention;

[0025] Figure 6Shown is a cross-sectional view of a clamping device according to an embodiment of the present invention;

[0026] Figure 7 Shown is a cross-sectional view of a vertical fixing rod and a transverse compression rod according to an embodiment of the present invention;

[0027] Figure 8 The figure shows the overall structure of a water bath pot according to an embodiment of the present invention;

[0028] Fig. 9 Shown is a diagram of the components of a water bath according to an embodiment of the present invention;

[0029] Fig.10 Shown is a cross-sectional view of a water bath pot according to an embodiment of the present invention;

[0030] Fig.11 The figure shows a structural diagram of a thermostat box according to an embodiment of the present invention;

[0031] Fig.12 Shown is an experimental flow chart of a method for measuring fluidity for investment casting according to an embodiment of the present invention.

[0032] Reference numerals

[0033] 1 rack, 11 storage table, 2 mold assembly, 21 upper template, 211 runner outlet, 22 lower template, 221 serpentine runner, 222 pouring inlet, 223 straight flow channel, 224 semicircular runner, 24 mold base, 241 vertical limit plate, 23 positioning pin, 3 pouring cup, 4 heating device, 41 container, 5 clamping device, 51 vertical fixing rod, 52 transverse pressure rod, 521 threaded hole, 522 buffer hole, 523 limit hole, 524 limit surface, 53 limit screw, 531 threaded rod, 532 limit rod, 54 limit spring, 61 water bath box, 62 first partition net, 63 upper cover, 64 heating tube, 71 second partition net, 72 oven box. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0035] This embodiment provides a fluidity measurement device for investment casting, such as Figure 1As shown, it includes: a frame 1, a mold assembly 2, a pouring cup 3 and a heating device 4. At least one of the mold assemblies 2 is arranged on the frame 1, so that multiple groups of experiments can be carried out at the same time, saving classroom experiment time. The pouring cup 3 is arranged on the mold assembly 2, and the heating device 4 is arranged on the frame 1. The frame 1, the mold assembly 2 and the pouring cup 3 are all made of stainless steel or aluminum alloy materials to prevent the equipment from rusting and difficult cleaning.

[0036] The frame 1 includes a storage table 11, which is used to store test materials and auxiliary tools such as cleaning shovels. The mold assembly 2, the pouring cup 3 and the heating device 4 are all arranged on the frame 1. The height of the frame 1 is designed with reference to ergonomics, which is easy to operate in experiments. Two, three, four or five or more mold assemblies 2 can be integrated on the frame 1 as needed. For example, when two mold assemblies 2 are integrated, the fluidity comparison experiment of two wax formulas under two temperature conditions can be completed simultaneously; when three mold assemblies 2 are integrated, the fluidity comparison experiment of two wax formulas under three temperature conditions can be completed simultaneously; when four mold assemblies 2 are integrated, the fluidity comparison experiment of two wax formulas under four temperature conditions can be completed simultaneously; when five mold assemblies 2 are integrated, the fluidity comparison experiment of two wax formulas under five temperature conditions can be completed simultaneously.

[0037] like Figures 2 to 4 As shown, the mold assembly 2 includes an upper template 21 and a lower template 22. The upper template 21 is arranged on the lower template 22. The upper template 21 is a transparent material plate, and the transparent material plate is one of a PC plate, an organic glass plate or a PAM plate. The transparent material plate is used as the upper template 21 to visualize the flow and molding process of the low-temperature mold material in the flow channel of the lower template 22 during the casting process, and it is easy to observe the experimental phenomenon. At the same time, combined with the visualized upper template 21, the surface morphology and quality of the sample obtained under different casting conditions can be intuitively observed.

[0038] The mold assembly 2 also includes a mold base 24, the lower mold plate 22 abuts against the vertical limit plate of the mold base 24, and the upper mold plate 21 is positioned with the lower mold plate 22 by a positioning pin 23 provided on the lower mold plate 22. The upper mold plate 21 is pressed against the lower mold plate 22 by an "L"-shaped clamping device 5 provided on the frame.

[0039] like Figures 5 to 7As shown, the clamping device 5 includes a vertical fixing rod 51 and a transverse pressing rod 52. One end of the vertical fixing rod 51 is fixed to the frame 1, and the other end of the vertical fixing rod 51 is connected to one end of the transverse pressing rod 52. A limit screw 53 is provided at the other end of the transverse pressing rod 52. The limit screw 53 presses the upper template 21 onto the lower template 22. A threaded hole 521, a buffer hole 522 and a limit hole 523 are sequentially provided at one end of the transverse pressing rod 52 away from the vertical fixing rod 51. The limit screw 53 includes a threaded rod 531 and a limit rod 532. The threaded hole 521, the buffer hole 522 and the limit hole 523 are coaxially arranged. The threaded rod 531 and the limit rod 532 are coaxially arranged. An internal thread is provided on the inner wall of the threaded hole 521, and an external thread is provided on the threaded rod 531. The internal thread cooperates with the external thread to realize the up and down rotation of the limit screw 53. The diameter of the buffer hole 522 is larger than the diameter of the threaded hole 521. A limit spring 54 is arranged in the buffer hole 522 and the threaded hole 521. One end of the limit spring 54 abuts against the limit surface 524 of the limit hole 523, and the other end of the limit spring 54 abuts against the lower surface of the threaded rod 531. The diameter of the threaded hole 521 is larger than the diameter of the limit hole 523. One end of the limit rod 532 is connected to the threaded rod 531, and the other end of the limit rod 532 extends out of the limit hole 523 and abuts against the upper template 21. When the threaded rod 531 rotates downward, the limit spring 54 is compressed to give the threaded rod 531 a resistance, which will remind the user to be careful, and the resistance becomes greater as the threaded rod 531 moves downward. The limit spring 54 first retreats into the buffer hole 522. When the limit spring 54 is tightened to the maximum compression amount, the threaded rod 531 cannot continue to rotate. At this time, the limit rod 532 is at the maximum stroke, and the limit spring 54 can avoid damage to the mold assembly 2 due to excessive tightening force.

[0040] The lower mold 22 is provided with a serpentine flow channel 221 on one side close to the upper mold 21, and a flow channel opening 211 is provided on the upper mold 21, and the flow channel opening 211 is communicated with a pouring inlet 222 of the serpentine flow channel 221. The serpentine flow channel 221 includes at least two direct flow channels 223 and at least one semicircular flow channel 224, and the two direct flow channels 223 are connected by the semicircular flow channel 224, and the pouring inlet 222 is connected to one end of the direct flow channel 223. In the design of the direct flow channel 223 and the semicircular flow channel 224, the lengths of the direct flow channel 223 and the semicircular flow channel 224 are usually designed to be fixed integer values, so as to facilitate the measurement and reading of experimental data.

[0041] The pouring cup 3 is connected to the pouring inlet 222 through the runner opening 211. The bottom of the pouring cup 3 is a tapered tube, the runner opening 211 is a tapered hole, the inner wall of the tapered hole matches the outer wall of the tapered tube, the tapered tube is accommodated in the tapered hole, and the pouring cup 3 is pressed against the upper template 21 under its own gravity to prevent the wax material from leaking during the pouring process.

[0042] The heating device 4 is arranged on the frame, and the heating device 4 is a constant temperature heating device. The constant temperature heating is a water bath or a constant temperature box. Figures 8 to 10 As shown, the water bath pot includes a water bath box 61, a first partition 62, an upper cover 63 and a heating tube 64. Water is injected into the water bath box 61, and heat is provided by the heating tube 64 to achieve constant temperature control. The material to be tested is placed in the container 41, and then placed in the water bath box 61 for heating. The first partition 62 separates the container 41 from the heating tube 64 to avoid uneven heating. The container 41 is a stainless steel beaker that can be used repeatedly to reduce experimental consumables.

[0043] like Fig.11 As shown, the thermostatic oven includes a second partition 71 and an oven body 72. The oven body 72 can be set to a temperature range of 40-300°C to achieve a constant temperature. The oven body 72 can accommodate four containers 41 at a time through the partition of the second partition 71.

[0044] The present invention also provides a method for measuring fluidity for investment casting, comprising the following steps: S10 test preparation, testing and cleaning a fluidity measuring device for investment casting. S20 configuring a material to be tested in a container, placing the container containing the material to be tested in a heating device, and heating the material to be tested according to the test temperature conditions so that the material to be tested is melted to obtain a molten material. S30 pouring the melted material to be tested into a mold assembly through a pouring cup, and recording pouring result data, the pouring result data including the surface quality of the sample, the sample filling length, and the flow time. And S40 waiting for the mold assembly to cool to room temperature, cleaning the material to be tested and resetting the fluidity measuring device for investment casting to complete the measurement of the material to be tested.

[0045] Wax material formula A and wax material formula B are used as the materials to be tested. Two sets of temperature experiments are performed for each material. The container 41 is a beaker. The fluidity measurement method is described as follows: Fig.12 As shown, the following steps are included:

[0046] S10 Test preparation, check the fluidity measuring device for investment casting, clean the dust and debris on the surface of the flow channel, and set up two mold assemblies 2, numbered 1# and 2# respectively.

[0047] S20: prepare wax formula A in two beakers, place the two beakers with the wax formula A in a heating device 4, number the two beakers 1'# and 2'# respectively, heat the 1'# beaker to 65° C. and heat the 2'# beaker to 75° C. to obtain a molten material.

[0048] S30: pour the molten material in the 1'# beaker into the 1# mold assembly through the pouring cup 3, and pour the molten material in the 2'# beaker into the 2# mold assembly through the pouring cup 3, and record the pouring result data, which includes the sample surface quality, sample filling length and flow time.

[0049] S40: cleaning the wax material, waiting for the mold assembly 2 to cool to room temperature, cleaning the mold assembly 2 and the wax material on the experimental table, and preparing for the next experiment.

[0050] Repeat step S20, add wax formula B to the two cleaned beakers, place the two beakers with the wax formula B in the heating device 4, heat the 1'# beaker to 65°C, and heat the 2'# beaker to 75°C to obtain a molten material.

[0051] Repeat step S30, pour the molten material in the 1'# beaker into the 1# mold assembly through the pouring cup 3, pour the molten material in the 2'# beaker into the 2# mold assembly through the pouring cup 3, and record the pouring result data, which includes the sample surface quality, sample filling length and flow time.

[0052] Repeat step S40, wait for the mold assembly 2 to cool to room temperature, clean the wax material and reset the fluidity measuring device for investment casting to complete the fluidity measurement of the wax material formula A and the wax material formula B.

[0053] The molten material starts to be injected from the upper end of the pouring cup 3, flows into the pouring inlet 222 through the pouring cup 3, and then flows in sequence along the serpentine flow channel 221. The molten material flows and fills the mold in the flow channel of the mold assembly 2. The flow process of the wax material can be directly observed through the transparent plate. When the cooling time of the molten material is reached, it is cooled, and finally the filling length after cooling is used to characterize its fluidity. At the same time, combined with the visual transparent plate, the surface morphology and quality of the samples obtained under different casting conditions can be directly observed. The flow lengths of different wax materials at two temperatures are shown in Table 1 below.

[0054] It can be seen from Table 1 that the higher the temperature, the longer the filling length, and different wax formulas have different flow lengths at the same temperature.

[0055] Table 1.

[0056]

[0057] The above description is only an exemplary embodiment of the present invention, and does not limit the scope of patent protection of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the scope of patent protection of the present invention.

Claims

1. A fluidity measuring device for investment casting, characterized in that: include: A mold assembly is arranged on a frame, each of the mold assemblies includes an upper mold plate and a lower mold plate, the upper mold plate is arranged on the lower mold plate, a serpentine flow channel is arranged on a side of the lower mold plate close to the upper mold plate, a flow channel opening is arranged on the upper mold plate, and the flow channel opening is communicated with a pouring inlet of the serpentine flow channel; a pouring cup is arranged on the upper mold plate, and the pouring cup is communicated with the pouring inlet through the flow channel opening; and a heating device is arranged on the frame, and the heating device adopts a constant temperature heating device; The rack includes a storage table, which is used to store test materials and cleaning shovel auxiliary tools; the mold assembly, the pouring cup and the heating device are all arranged on the rack, and the height of the rack is designed with reference to ergonomics, which is easy for experimental operation; 2, 3, 4 or 5 mold assemblies are integrated on the rack as needed; The upper template is a transparent material plate; The transparent material plate is one of a PC plate, an organic glass plate or a PAM plate.

2. The fluidity measuring device for investment casting according to claim 1, characterized in that: The constant temperature heating is a water bath or a constant temperature box.

3. The fluidity measuring device for investment casting according to claim 1, characterized in that: The mold assembly also includes a mold base and a clamping device, the mold base is arranged on the frame, and the lower mold plate is arranged on the mold base; the clamping device includes a vertical fixing rod and a transverse pressure rod, one end of the vertical fixing rod is fixed to the frame, the other end of the vertical fixing rod is connected to one end of the transverse pressure rod, and a limiting screw is arranged at the other end of the transverse pressure rod, and the limiting screw presses the upper mold plate onto the lower mold plate.

4. The fluidity measuring device for investment casting according to claim 3, characterized in that: A threaded hole, a buffer hole and a limit hole are sequentially arranged at one end of the transverse pressure rod away from the vertical fixing rod, and the limit screw includes a threaded rod and a limit rod, and the threaded hole, the buffer hole and the limit hole are coaxially arranged, and the threaded rod and the limit rod are coaxially arranged; an internal thread is arranged on the inner wall of the threaded hole, and an external thread is arranged on the threaded rod, and the internal thread cooperates with the external thread to realize the up and down rotation of the limit screw, the diameter of the buffer hole is larger than the diameter of the threaded hole, and the diameter of the threaded hole is larger than the diameter of the limit hole, one end of the limit rod is connected to the threaded rod, and the other end of the limit rod extends out of the limit hole and abuts against the upper template.

5. The fluidity measuring device for investment casting according to claim 1, characterized in that: The serpentine flow channel includes at least two straight flow channels and at least one semicircular flow channel, the two straight flow channels are connected through the semicircular flow channel, and the pouring inlet is connected to one end of one of the straight flow channels.

6. A method for measuring fluidity for investment casting based on the fluidity measuring device for investment casting according to claim 1, characterized in that: The method comprises the following steps: S10 test preparation, testing and cleaning a fluidity measuring device for investment casting; S20 configuring a material to be tested in a container, placing the container containing the material to be tested in a heating device, and heating the container according to the test temperature conditions to melt the material to be tested to obtain a molten material; S30 pouring the melted material to be tested into a mold assembly through a pouring cup, and recording pouring result data, wherein the pouring result data includes sample surface quality, sample filling length, and flow time; and S40 waiting for the mold assembly to cool to room temperature, cleaning the material to be tested, and resetting the fluidity measuring device for investment casting to complete the measurement of the material to be tested.

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