CN111710225A - Fluidity measuring device and method for investment casting - Google Patents

Abstract

The invention provides a fluidity measuring device for investment casting, which comprises: the mold assemblies are arranged on the rack, each mold assembly comprises an upper template and a lower template, the upper template is arranged on the lower template, one surface of the lower template, which is close to the upper template, is provided with a snake-shaped runner, the upper template is provided with a runner port, and the runner port is communicated with a pouring inlet of the snake-shaped runner; the pouring cup is arranged on the upper template and communicated with the pouring inlet through the runner opening; and the heating device is arranged on the rack and adopts a constant-temperature heating device. According to the fluidity measuring device and the fluidity measuring device for investment casting, the heating device adopts a water bath or a thermostat, so that fire hazard caused by heating by adopting an open fire electric furnace in the experimental process is avoided, and meanwhile, the electric furnace adopts constant temperature to heat the material to be measured, so that the temperature of the material to be measured is easy to control, and energy waste is prevented.

Description

Fluidity measuring device and method for investment casting

Technical Field

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

Background

Casting is one of the basic processes of the modern basic machinery manufacturing industry. The fluidity experiment related to the casting process is a basic experiment course of mechanical engineering specialties of ordinary colleges and universities. Through the fluidity experimental teaching, students can know the concept, the testing method and the influencing factors of the fluidity of the material, and meanwhile, the students can comprehensively know the basic knowledge of engineering materials and material forming.

Traditional fluidity experiment teaching mainly focuses on the field of aluminum alloy materials, and fluidity is one of casting performances of alloy and directly influences the mold filling capacity of liquid alloy. The better the fluidity of the alloy, the stronger the mold filling capability, the more the casting with clear outline, thin wall and complex can be cast, and simultaneously the alloy is also beneficial to the floating and discharging of impurities and gas and the shrinkage and repair in the solidification process; and the alloy with poor fluidity is difficult to fill the die cavity, the die filling capability is reduced, and the defects of insufficient casting, cold shut, air holes, slag inclusion and the like are easy to generate.

With the development of the technology, investment casting is gradually developed. Investment casting, also known as precision casting or lost wax casting, is a process in which a fusible material (wax, etc.) is used to make a precise fusible pattern, a plurality of layers of refractory coatings are applied to the pattern, the pattern is dried and hardened to form an integral shell, the lost wax is melted by heating the shell, the shell is baked at high temperature to form a refractory shell, liquid metal is poured into the shell, and the shell is cooled to form a casting. The main advantages of investment casting over other casting methods are as follows: the casting has high dimensional precision and low surface roughness, can cast castings with complex shapes, generally has precision reaching 5-7 level and roughness reaching two Ra25-6.3 mu m; the casting method can be used for casting thin-wall castings and castings with small weight, the minimum wall thickness of the investment casting can reach 0.5mm, and the weight can be as small as several grams; the casting with fine patterns, characters and fine grooves and bent pores can be cast; the shape and the inner cavity shape of the investment casting are almost not limited, parts with complex shapes which are difficult to manufacture by sand casting, forging, cutting processing and other methods can be manufactured, and some assemblies and welding parts can be directly cast into integral parts after structural improvement, so that the weight of the parts is reduced, and the production cost is reduced; the type of casting alloy is almost unlimited and is commonly used for casting alloy steel parts, carbon steel parts and heat-resistant alloy castings; production batches are not limited and can range from single-piece to batch mass production. With the development of investment casting technology, the variety of the mould materials is increasingly diversified, and the compositions are different. The molding materials are generally divided into high-temperature, medium-temperature and low-temperature molding materials according to the melting point of the molding materials. The melting point of the low-temperature mould material is about 60 ℃, and the paraffin-stearic acid mixture widely applied in China is used as the low-temperature mould material. The melting point of the high-temperature mould material is higher than 120 ℃, and the mould material consisting of 50% of rosin, 20% of ozokerite and 30% of polystyrene is a typical high-temperature mould material. The melting point of the medium-temperature mould material is between the two types of mould materials, and the existing medium-temperature mould material can be basically divided into two types of rosin-based mould material and wax-based mould material.

In the experimental practice teaching of various colleges and universities, some fluidity measurement teaching experiments are usually carried out in order to present the investment casting process to students, and the fluidity measurement teaching experiments are realized by a fluidity measurement teaching device. The melting process of the current fluidity measurement teaching device adopts an open fire electric furnace, fire hazard exists in the measuring process, the electric furnace is used for heating low-temperature mould material, the temperature is not easy to control, the heating temperature is easily overhigh, smoke and other waste gas is generated, and the test condition is inconvenient to control.

Disclosure of Invention

In order to solve the problems, the invention provides a fluidity measuring device and a fluidity measuring method for investment casting.

In order to achieve the above purpose, the invention adopts a technical scheme that:

a fluidity measuring device for investment casting, comprising: the mold assemblies are arranged on the rack, each mold assembly comprises an upper template and a lower template, the upper template is arranged on the lower template, one surface of the lower template, which is close to the upper template, is provided with a snake-shaped runner, the upper template is provided with a runner port, and the runner port is communicated with a pouring inlet of the snake-shaped runner; the pouring cup is arranged on the upper template and communicated with the pouring inlet through the runner opening; and the heating device is arranged on the rack and adopts a constant-temperature heating device.

Further, the constant-temperature heating is a water bath or a constant-temperature box.

Further, the die assembly further comprises a die base and a clamping device, the die base is arranged on the rack, and the lower template is arranged on the die base; the clamping device comprises a vertical fixing rod and a transverse pressing rod, one end of the vertical fixing rod is fixed on the rack, the other end of the vertical fixing rod is connected with one end of the transverse pressing rod, the other end of the transverse pressing rod is provided with a limiting screw, and the upper template is pressed on the lower template through the limiting screw.

Furthermore, one end of the transverse pressure rod, which is far away from the vertical fixed rod, is sequentially provided with a threaded hole, a buffer hole and a limiting hole, the limiting screw comprises a threaded rod and a limiting rod, the threaded hole, the buffer hole and the limiting hole are coaxially arranged, and the threaded rod and the limiting rod are coaxially arranged; be equipped with the internal thread on the threaded hole inner wall, be equipped with the external screw thread on the threaded rod, the internal thread with external screw thread fit realizes the stop screw is the tilting, the diameter of buffer hole is greater than the diameter of screw hole, the diameter of screw hole is greater than the diameter of spacing hole, the one end of gag lever post with the threaded rod is connected, the other end of gag lever post stretches out spacing hole butt is in on the cope match-plate pattern.

Furthermore, the snake-shaped runner comprises at least two straight runners and at least one semicircular runner, the two straight runners are connected through the semicircular runner, and the pouring inlet is connected with one end of one straight runner.

Further, the upper template is a transparent material plate.

Further, the transparent material plate is one of a PC plate, an organic glass plate, or a paml plate.

The invention also provides a fluidity measuring method for investment casting, which comprises the following steps: s10 test preparation, namely detecting and cleaning the fluidity measuring device for investment casting; s20, configuring a material to be tested in a container, placing the container filled with the material to be tested in a heating device, and heating according to the test temperature condition to melt the material to be tested to obtain a molten material; s30, pouring the melted material to be tested into a mould assembly through a pouring cup, and recording pouring result data, wherein the pouring result data comprises sample surface quality, sample filling length and flowing time; and S40, when the die assembly is cooled to the room temperature, cleaning the material to be measured and resetting the fluidity measuring device for investment casting to finish the measurement of the material to be measured.

Compared with the prior art, the technical scheme of the invention has the following advantages:

(1) according to the fluidity measuring device and the fluidity measuring method for investment casting, the heating device adopts a water bath or a thermostat, so that fire hazard caused by heating by adopting an open-fire electric furnace in the experimental process is avoided, and meanwhile, the electric furnace adopts constant temperature to heat the material to be measured, so that the temperature of the material to be measured is easy to control, and energy waste is prevented.

(2) According to the fluidity measuring device and the fluidity measuring method for investment casting, the upper template is clamped with the lower template through the clamping device, so that the assembling time of the die assembly is reduced, and meanwhile, the clamping device is provided with the buffer holes and the limiting springs, so that the damage of the clamping device to the die assembly in the assembling process of the upper template and the lower template can be avoided.

Drawings

The technical solution and the advantages of the present invention will be apparent from the following detailed description of the embodiments of the present invention with reference to the accompanying drawings.

FIG. 1 is a view showing the construction of a fluidity measuring apparatus for investment casting according to an embodiment of the present invention;

FIG. 2 is a block diagram of a mold assembly according to one embodiment of the present invention;

FIG. 3 is a lower template structure according to an embodiment of the present invention;

FIG. 4 is a cross-sectional view of the mold assembly and the pouring cup after they are connected according to one embodiment of the invention;

FIG. 5 is a schematic view of a clamping device according to an embodiment of the present invention;

FIG. 6 is a cross-sectional view of a clamping device according to an embodiment of the invention;

FIG. 7 is a cross-sectional view of a vertical fixation rod and a lateral compression rod of one embodiment of the present invention;

FIG. 8 is a view showing an overall structure of a water bath according to an embodiment of the present invention;

FIG. 9 is a view of the components of a water bath according to an embodiment of the present invention;

FIG. 10 is a sectional view of a water bath according to an embodiment of the present invention;

FIG. 11 is a view showing a structure of an incubator in accordance with an embodiment of the present invention;

FIG. 12 is a flow chart of the fluidity measurement method for investment casting according to an embodiment of the present invention.

Reference numerals

The device comprises a machine frame 1, an 11 storage table, a2 mold assembly, a 21 upper mold plate, a 211 runner port, a 22 lower mold plate, a 221 snake-shaped runner, a 222 pouring inlet, a 223 straight runner, a 224 semicircular runner, a 24 mold base, a 241 vertical limiting plate, 23 positioning pins, a 3 pouring cup, a 4 heating device, a 41 container, a 5 clamping device, a 51 vertical fixing rod, a 52 transverse pressing rod, a 521 threaded hole, a 522 buffer hole, a 523 limiting hole, a 524 limiting surface, 53 limiting screws, 531 threaded rods, 532 limiting rods, 54 limiting springs, a 61 water bath box body, 62 first separation nets, 63 upper covers, 64 heating pipes, 71 second separation nets and 72 oven box bodies.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The present embodiment provides a fluidity measuring apparatus for investment casting, as shown in fig. 1, including: frame 1, mould assembly 2, pouring basin 3 and heating device 4. At least one of the die assemblies 2 is arranged on the rack 1, so that multiple groups of experiments can be carried out simultaneously, and the classroom experiment time is saved. The pouring cup 3 is arranged on the die assembly 2, and the heating device 4 is arranged on the frame 1. The frame 1 the mould subassembly 2 and pouring basin 3 all adopts stainless steel material or aluminum alloy material preparation, prevents that equipment from rustting, and the clearance is difficult.

The rack 1 comprises a storage table 11, wherein the storage table 11 is used for containing test materials and auxiliary appliances such as a cleaning shovel. The die assembly 2, the pouring cup 3 and the heating device 4 are all arranged on the rack 1, and the height design of the rack 1 refers to human engineering, so that the experimental operation is easy. 2, 3, 4 or 5 or more of the mould assemblies 2 may be integrated on the frame 1 as required. For example, when 2 mould assemblies 2 are integrated, the fluidity comparison experiment of two wax formulations under two temperature conditions can be simultaneously completed; when 3 die assemblies 2 are integrated, the fluidity comparison experiment of two wax material formulas under three temperature conditions can be completed at the same time; when 4 mould assemblies 2 are integrated, a flowability comparison experiment of two wax material formulas under four temperature conditions can be completed at the same time; when 5 mould assemblies 2 are integrated, the flowability comparison experiment of two wax formulations under five temperature conditions can be simultaneously completed.

As shown in fig. 2 to 4, the mold assembly 2 includes an upper mold plate 21 and a lower mold plate 22, the upper mold plate 21 is disposed on the lower mold plate 22, the upper mold plate 21 is a transparent material plate, and the transparent material plate is one of a PC plate, an organic glass plate, or a paml plate. The transparent material plate is used as the upper template 21, so that the flowing and forming processes of the low-temperature die material in the runner of the lower template 22 in the pouring process are visualized, and the experimental phenomenon is easy to observe. Meanwhile, the visual upper template 21 is combined, so that the surface appearance and the quality of the sample obtained under different pouring conditions can be visually observed.

The die assembly 2 further comprises a die base 24, the lower die plate 22 abuts against a vertical limiting plate of the die base 24, and the upper die plate 21 is located on the lower die plate 22 through a locating pin 23 arranged on the lower die plate 22. The upper template 21 is pressed with the lower template 22 through an L-shaped clamping device 5 arranged on the frame.

As shown in fig. 5 to 7, the clamping device 5 includes a vertical fixing rod 51 and a horizontal pressing rod 52, one end of the vertical fixing rod 51 is fixed on the frame 1, the other end of the vertical fixing rod 51 is connected to one end of the horizontal pressing rod 52, the other end of the horizontal pressing rod 52 is provided with a limit screw 53, and the limit screw 53 presses the upper die plate 21 onto the lower die plate 22. The horizontal depression bar 52 is kept away from the one end of vertical dead lever 51 sets gradually screw hole 521, buffer hole 522 and spacing hole 523, stop screw 53 includes threaded rod 531 and gag lever post 532, screw hole 521 the buffer hole 522 and spacing hole 523 sets up with the axle center, threaded rod 531 with the axle center setting of gag lever post 532. The inner wall of the threaded hole 521 is provided with an internal thread, the threaded rod 531 is provided with an external thread, the internal thread is matched with the external thread to realize the vertical rotation of the limit screw 53, the diameter of the buffer hole 522 is larger than that of the threaded hole 521, the buffer hole 522 and the threaded hole 521 are internally provided with a limit spring 54, one end of the limit spring 54 is abutted against a limit surface 524 of the limit hole 523, the other end of the limit spring 54 is abutted against the lower surface of the threaded rod 531, the diameter of the threaded hole 521 is larger than that of the limit hole 523, one end of the limit rod 532 is connected with the threaded rod 531, and the other end of the limit rod 532 extends out of the limit hole 523 and is abutted against the upper template 21. When the threaded rod 531 rotates downwards, the limiting spring 54 is compressed to provide resistance to the threaded rod 531, which may remind a user of caution, and the resistance increases as the threaded rod 531 moves downwards, the limiting spring 54 first recedes into the buffer hole 522, when the limiting spring 54 is tightened to the maximum compression amount, the threaded rod 531 may not rotate continuously, and at this time, the limiting rod 532 reaches the maximum stroke, and the limiting spring 54 may avoid the damage to the mold assembly 2 due to the excessive tightening force.

A serpentine runner 221 is arranged on one side of the lower template 22 close to the upper template 21, a runner port 211 is arranged on the upper template 21, and the runner port 211 is communicated with a pouring inlet 222 of the serpentine runner 221. The serpentine runner 221 includes at least two straight runners 223 and at least one semicircular runner 224, the two straight runners 223 are connected through the semicircular runner 224, and the pouring inlet 222 is connected to one end of one straight runner 223. In the design of the straight flow channel 223 and the semicircular flow channel 224, the lengths of the straight flow channel 223 and the semicircular flow channel 224 are generally designed to be fixed integer values so as to facilitate the measurement and reading of experimental data.

The pouring cup 3 communicates with the pouring inlet 222 through the runner port 211. The bottom of the pouring cup 3 is a conical pipe, the runner port 211 is a conical hole, the inner wall of the conical hole is matched with the outer wall of the conical pipe, the conical pipe is accommodated in the conical hole, the pouring cup 3 is tightly pressed with the upper template 21 under the action of self gravity, and leakage of wax materials in the pouring process is avoided.

The heating device 4 is arranged on the rack, and the heating device 4 adopts a constant-temperature heating device. The constant-temperature heating is a water bath or a constant-temperature box. As shown in fig. 8-10, the water bath kettle comprises a water bath box body 61, a first separation net 62, an upper cover 63 and a heating pipe 64, water is injected into the water bath box body 61, and heat is provided through the heating pipe 64, so that the regulation and control of constant temperature can be realized. The material to be measured is placed in the container 41 and then placed in the water bath box 61 for heating, and the first separation net 62 separates the container 41 from the heating pipe 64, so that uneven heating is avoided. The 41-position stainless steel metal beaker of the container can be used repeatedly, so that the experimental consumables are reduced.

As shown in fig. 11, the oven includes a second screen 71 and an oven body 72, and the oven body 72 can set a temperature range of 40-300 ℃ to achieve a constant temperature. The oven body 72 can accommodate 4 containers 41 at a time through the partition of the second partition net 71.

The invention also provides a fluidity measuring method for investment casting, which comprises the following steps: and S10 test preparation, namely detecting and cleaning the fluidity measuring device for investment casting. S20, a material to be measured is configured in a container, the container filled with the material to be measured is placed in a heating device, and the material to be measured is melted to obtain a molten material by heating according to the test temperature condition. S30, pouring the melted material to be tested into the mould assembly through the pouring cup, and recording pouring result data, wherein the pouring result data comprises the surface quality of the sample, the filling length of the sample and the flowing time. And S40, when the die assembly is cooled to the room temperature, cleaning the material to be measured and resetting the fluidity measuring device for investment casting to finish the measurement of the material to be measured.

Taking a wax formula A and a wax formula B as materials to be measured, performing two temperature experiments on each material, and taking the container 41 as a beaker to explain the fluidity measuring method, as shown in fig. 12, the method comprises the following steps:

s10 test preparation, the fluidity measuring device for investment casting is checked, surface floating dust and sundries such as a runner and the like are cleaned, and two die assemblies 2 are respectively provided with numbers 1# and 2 #.

S20 wax formula A is prepared in two beakers, the two beakers filled with the wax formula A are placed in a heating device 4, the two beakers are numbered 1 '#and2' #respectively, the 1 '# beaker is heated to 65 ℃, and the 2' # beaker is heated to 75 ℃, so that a molten material is obtained.

S30 casting the melt of the 1 '# beaker into the 1# mold assembly through the pouring cup 3 and the melt of the 2' # beaker into the 2# mold assembly through the pouring cup 3, and recording the casting result data including the surface quality of the specimen, the filling length of the specimen and the flow time. And

s40, cleaning the wax material, and after the mould assembly 2 is cooled to room temperature, cleaning the wax material on the mould assembly 2 and the experiment table to prepare for the next experiment.

And repeating the step of S20, preparing a wax material formula B in the two cleaned beakers, placing the two beakers filled with the wax material formula B in a heating device 4, heating the 1 '# beaker to 65 ℃, and heating the 2' # beaker to 75 ℃ to obtain a molten material.

Repeating the step of S30, pouring the molten material of the 1 '# beaker into the 1# mold assembly through the pouring cup 3, pouring the molten material of the 2' # beaker into the 2# mold assembly through the pouring cup 3, and recording the pouring result data, wherein the pouring result data comprises the surface quality of the sample, the filling length of the sample and the flowing time.

And repeating the step S40, and after the mould assembly 2 is cooled to the room temperature, cleaning the wax material and resetting the fluidity measuring device for investment casting, so as to finish the fluidity measurement of the wax material formula A and the wax material formula B.

The molten material is injected from the upper end of the pouring cup 3, flows into the pouring inlet 222 through the pouring cup 3 and then flows along the snake-shaped flow channel 221 in sequence, the molten material flows and fills the mold in the flow channel of the mold assembly 2, the flowing process of the wax material can be directly observed through the transparent plate, the molten material is cooled after the cooling time of the molten material is reached, and finally the flowing quality of the molten material is represented by the filling length after cooling. And meanwhile, the visual transparent plate is combined, so that the surface appearance and quality of the sample obtained under different pouring conditions can be visually observed. Flow re-length at two temperatures for different wax materials is shown in Table 1 below

It can be seen from table 1 that the higher the temperature, the longer the mold length, and the different wax formulations also have different flow lengths at the same temperature.

Table 1.

The above description is only an exemplary embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent structures or equivalent processes that are transformed by the content of the present specification and the attached drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims (8)

1. A fluidity measuring device for investment casting, characterized by comprising:

the mold assemblies are arranged on the rack, each mold assembly comprises an upper template and a lower template, the upper template is arranged on the lower template, one surface of the lower template, which is close to the upper template, is provided with a snake-shaped runner, the upper template is provided with a runner port, and the runner port is communicated with a pouring inlet of the snake-shaped runner;

the pouring cup is arranged on the upper template and communicated with the pouring inlet through the runner opening; and

and the heating device is arranged on the rack and adopts a constant-temperature heating device.

2. The fluidity measuring device for investment casting according to claim 1, wherein the constant temperature heating is a water bath or an oven.

3. The fluidity measuring device for investment casting according to claim 1, wherein the mold assembly further comprises a mold base and a clamping device, the mold base is arranged on the frame, and the lower template is arranged on the mold base; the clamping device comprises a vertical fixing rod and a transverse pressing rod, one end of the vertical fixing rod is fixed on the rack, the other end of the vertical fixing rod is connected with one end of the transverse pressing rod, the other end of the transverse pressing rod is provided with a limiting screw, and the upper template is pressed on the lower template through the limiting screw.

4. The fluidity measuring device for investment casting according to claim 3, wherein one end of the transverse pressure bar, which is far away from the vertical fixing bar, is provided with a threaded hole, a buffer hole and a limiting hole in sequence, the limiting screw comprises a threaded rod and a limiting bar, the threaded hole, the buffer hole and the limiting hole are arranged coaxially, and the threaded rod and the limiting bar are arranged coaxially; be equipped with the internal thread on the threaded hole inner wall, be equipped with the external screw thread on the threaded rod, the internal thread with external screw thread fit realizes the stop screw is the tilting, the diameter of buffer hole is greater than the diameter of screw hole, the diameter of screw hole is greater than the diameter of spacing hole, the one end of gag lever post with the threaded rod is connected, the other end of gag lever post stretches out spacing hole butt is in on the cope match-plate pattern.

5. The fluidity measuring device for investment casting according to claim 1, wherein the serpentine flow passage comprises at least two straight flow passages and at least one semicircular flow passage, the two straight flow passages are connected through the semicircular flow passage, and the pouring inlet is connected to one end of one of the straight flow passages.

6. The apparatus for measuring fluidity for investment casting according to claim 1, wherein the upper mold plate is a transparent material plate.

7. The apparatus of claim 6 wherein the sheet of transparent material is one of a PC sheet, plexiglass sheet or Permet sheet.

8. A fluidity measuring method for investment casting is characterized by comprising the following steps:

s10 test preparation, namely detecting and cleaning the fluidity measuring device for investment casting;

s20, configuring a material to be tested in a container, placing the container filled with the material to be tested in a heating device, and heating according to the test temperature condition to melt the material to be tested to obtain a molten material;

s30, pouring the melted material to be tested into a mould assembly through a pouring cup, and recording pouring result data, wherein the pouring result data comprises sample surface quality, sample filling length and flowing time; and

s40, when the die assembly is cooled to the room temperature, cleaning the material to be measured, and resetting the fluidity measuring device for investment casting to finish the measurement of the material to be measured.

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