A casting jolting device and lost foam precision casting process

Abstract

The application discloses a casting vibration device and a lost foam precision casting process, and relates to the technical field of lost foam precision casting. The casting vibration device is used for vibration of a casting sand box, the casting sand box is used for placing a model and casting sand, and comprises a vibration rod. One end of the vibration rod is provided with a constant moment structure, and the constant moment structure is connected with a reciprocating mechanism. The application adopts the form of the vibration rod with a cavity penetrating on the sand box, and matches the constant moment and the reciprocating mechanism, thereby simultaneously solving the problems that the existing lost foam model vibration method excessively relies on experience, the vibration effect degree cannot be quantified, and the existing lost foam vacuum pouring method is a method of setting a vacuum pipe on the sand box to perform vacuumizing. The vacuumizing effect is mainly concentrated near the vacuum pipe. When the vacuum pipe is filled with casting sand, the vacuum cannot act on the casting sand at other positions, thereby causing the problem of limited vacuum effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of lost foam precision casting technology, in particular to a casting tamping device and lost foam precision casting process. BACKGROUND

[0002] Casting is a method of pouring liquid metal into a casting cavity adapted to the shape of the part, and after cooling and solidification, a part or blank is obtained. The traditional casting model needs to be tamped in the sand box to ensure the stability of the inner cavity after removal. In lost foam casting, the casting sand around the lost foam in the sand box also needs to be tamped to ensure the stability of the subsequent pouring. In addition, if the method of vibrating while pouring is used, it can prevent the casting sand from being scattered and thus causing poor part shape.

[0003] The Chinese invention with application number CN201010278501.8 relates to a lost foam casting model boxing method, which mainly tamps the sand box according to experience, and the tamping effect is limited. The method of vibrating while pouring still causes deformation and iron pack sand problems. If the vacuum method is used for pouring, it is more likely to cause the above problems.

[0004] In addition, the existing lost foam vacuum pouring process uses a vacuum pipe on the sand box to perform vacuumizing. The vacuumizing effect is mainly concentrated near the vacuum pipe. When the vacuum pipe is filled with casting sand, the vacuum cannot act on the casting sand at other positions (such as Figure 1 ), thereby causing limited vacuum effect.

[0005] Lost foam casting is a dry sand casting with foam plastic mold using binder-free dry sand combined with vacuum technology. Lost foam is prone to carbonization defects. The main reason for carbonization defects is that the foam material contains carbon. During pouring, the foam decomposes and releases free carbon, which invades the molten steel.

[0006] Therefore, based on years of experience in design, development and practical production in the relevant industry, the present applicant has researched and improved the existing tamping method and lost foam precision casting process, and provides a casting tamping device and lost foam precision casting process. SUMMARY

[0007] (I) Technical problems solved

[0008] In view of the deficiencies of the prior art, the present application provides a casting tamping device and lost foam precision casting process, which solves the following technical problems:

[0009] 1. The existing lost foam model tamping method relies too much on experience, and the tamping effect cannot be quantified.

[0010] 2. The existing lost foam vacuum casting method involves setting up a vacuum tube on the sand box to create a vacuum. The vacuum effect is mainly concentrated near the vacuum tube. Once the vacuum tube is filled with casting sand, the vacuum cannot be applied to the casting sand in other areas, resulting in a limited vacuum effect.

[0011] 3. Existing lost foam casting is prone to carbon enrichment defects. The main reason for carbon enrichment defects is that the foam material contains carbon. During casting, the foam burns and decomposes to release free carbon, which then invades the molten steel.

[0012] (II) Technical Solution

[0013] To achieve the above objectives, the present invention provides the following technical solution: a vibration compaction device for casting, used for compacting a casting sand box, wherein the casting sand box is used to hold a model and casting sand, and includes a vibrating rod that penetrates the casting sand box and is rotatably connected to it. The vibrating rod is used to vibrate the casting sand to compact it. The vibrating rod is positioned in a location within the casting sand box that is difficult to compact, and includes a reciprocating mechanism. The vibrating rod has a protrusion, and one end of the vibrating rod has a constant torque structure connected to the reciprocating mechanism.

[0014] The constant torque structure can prevent the reciprocating mechanism from continuing to transmit torque to the vibrating rod after the vibrating rod is fixed.

[0015] Preferably, the constant torque structure includes a constant torque disk, which is sleeved on one end of the vibrating rod. A blind hole is provided on the inner side of the constant torque disk, and a spring is connected inside the blind hole. A slider is connected to the end of the spring, and the slider abuts against the surface of the vibrating rod. The slider can drive the vibrating rod to rotate.

[0016] When the torque on the constant torque disk is too large, the constant torque disk can rotate relative to the vibrating rod.

[0017] Preferably, the reciprocating mechanism is one of a Scottish yoke and a crank-slider mechanism;

[0018] When the reciprocating mechanism is a Scottish yoke, the reciprocating mechanism includes a turntable, a vertical rod, a horizontal rod, and a sliding sleeve. The vertical rod has a groove, and the turntable has a pin that can slide within the groove. One side of the vertical rod is connected to the horizontal rod, and the horizontal rod has teeth. The horizontal rod passes through the sliding sleeve and is slidably connected to it. The torque plate is a gear, and the torque plate meshes with the teeth on the horizontal rod.

[0019] Preferably, the vibrating rod is a tube structure with a cavity inside, and a through hole is provided on the protrusion, which communicates with the cavity, and the cavity is used for vacuuming.

[0020] Preferably, a filter element is disposed inside the through hole.

[0021] A lost foam precision casting process, including model manufacturing of lost foam, model coating, box molding, compaction, pouring, including a casting compaction device;

[0022] The compaction includes the following steps:

[0023] S1.1: Place the casting sand box on the compaction table;

[0024] S1.2: Put the model into the casting sand box, and start filling the casting sand, start the reciprocating mechanism during the filling of the casting sand, so that the reciprocating mechanism drives the vibration rod to rotate back and forth through the constant torque structure until the casting sand around the vibration rod is compacted to the reciprocating mechanism drives the constant torque structure to idle;

[0025] S1.3: After the casting sand is filled, prepare for the subsequent step.

[0026] Preferably, the pouring includes the following steps:

[0027] S2.1: Connect the vacuum device to the cavity of the vibration rod and open the vacuum device;

[0028] S2.2: Start pouring, vibrate the casting sand box during pouring, and maintain the vacuum degree in the cavity;

[0029] S2.3: After pouring is completed, prepare for the subsequent step.

[0030] Preferably, the coating thickness of the model coating is greater than 5mm.

[0031] Preferably, the model coating is a multi-layer coating, and the first layer of coating is a surface coating.

[0032] Preferably, after the model coating, the model is heated to a smooth cavity with the coating of the model as the inner surface.

[0033] (Three) beneficial effects

[0034] The present application provides a casting compaction device and a lost foam precision casting process. It has the following beneficial effects:

[0035] (1) The casting compaction device and the lost foam precision casting process adopt a constant torque structure and a vibration rod that penetrates the sand box, which can effectively quantitatively control the degree of compaction, and the precision requirement of the reciprocating structure is not high, greatly saving the investment cost.

[0036] (2) The casting compaction device and the lost foam precision casting process combine the vacuum pipe with the vibration rod, the vibration rod can be used for vacuumizing after vibrating the sand box, the range of vacuum action is increased, which effectively prevents the box from collapsing, and the gas generated during pouring can also be promptly removed.

[0037] (3), the casting of the compaction device and the lost foam precision casting process will model the coating thickening, and the coating solidification after the lost foam model heating and melting, make the coating star inside the smooth cavity, avoid because the lost foam model foam plastic model in the carbon into the molten steel. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 is the schematic diagram of the vacuum range of the existing vacuum extraction mode;

[0039] Figure 2 is the schematic diagram of the structure of the compaction device;

[0040] Figure 3 is the A-A sectional view;

[0041] Figure 4 is the A-A sectional view; Figure 2 is the A-A sectional view;

[0042] Figure 5 is the schematic diagram of the compaction device in use;

[0043] Figure 6 is the schematic diagram of the vacuum range of the compaction device.

[0044] In the figure: 1, the casting sand box;11, bearing;2, vibration rod;21, protrusion;211, through hole;22,;3, rotating disc;31, pin;4, constant moment disc;41, sliding block;42, spring;5, vertical rod;51, cross rod;52, sliding sleeve;53, sliding groove;6, gearbox;7, motor;8, model. DETAILED DESCRIPTION

[0045] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the present application.

[0046] Example 1: basic structure to solve the problem that the existing lost foam model compaction method relies too much on experience and cannot quantify the degree of compaction effect

[0047] As Figures 2 to 4A kind of casting vibration device, for the vibration of casting sand box 1, casting sand box 1 is used to put into model 8 and casting sand, including vibration rod 2, vibration rod 2 is through casting sand box 1 and is rotatably connected with casting sand box 1, vibration rod 2 is used to vibrate casting sand and make it compact, vibration rod 2 is arranged in the position of casting sand box 1 not easy to compact, including reciprocating mechanism, vibration rod 2 is provided with protrusion 21, one end of vibration rod 2 is provided with constant torque structure, and constant torque structure is connected with reciprocating mechanism;

[0048] Wherein:

[0049] The position not easy to compact can be the position of model 8 internal corner and upper model 8 structure blockage, such as Figure 5 .

[0050] In order to reduce the friction of vibration rod 2 and casting sand box 1, bearing 11 can be arranged on the position corresponding to vibration rod 2 of casting sand box 1.

[0051] Constant torque structure can prevent reciprocating mechanism from continuing to transmit torque to vibration rod 2 after vibration rod 2 is fixed.

[0052] Constant torque structure can be as follows:

[0053] Including constant torque disc 4, constant torque disc 4 is sleeved on one end of vibration rod 2, blind hole is formed on the inner side of constant torque disc 4, spring 42 is connected in blind hole, the end of spring 42 is connected with sliding block 41, and sliding block 41 abuts against the surface of vibration rod 2, and sliding block 41 can drive vibration rod 2 to rotate.

[0054] When the torque of constant torque disc 4 is too large, constant torque disc 4 can rotate relative to vibration rod 2.

[0055] In order to prevent sliding block 41 from sliding on vibration rod 2, recess can be arranged on the corresponding position of vibration rod 2 and matched with sliding block 41.

[0056] The torque that constant torque disc 4 can bear is not the larger the better, if the torque that can be borne is too large, reciprocating mechanism will always drive vibration rod 2 to rotate through constant torque disc 4, and then make casting sand not in compact state or destroy compact state. Therefore, before use, the maximum torque that constant torque disc 4 can bear can be determined by the characteristics of casting sand and the requirement of compact degree by the person skilled in the art through limited times of test, for example: if the compact degree is required to be higher, the maximum torque that constant torque disc 4 can bear can be increased by increasing the stiffness coefficient of spring 42.

[0057] If the compact degree is required to be lower, the maximum torque that constant torque disc 4 can bear can be reduced by reducing the stiffness coefficient of spring 42.

[0058] The reciprocating mechanism is a Scotch yoke, and the reciprocating mechanism comprises a rotating disc 3, a vertical rod 5, a cross rod 51 and a sliding sleeve 52, the vertical rod 5 is provided with a sliding groove 53, the rotating disc 3 is provided with a pin 31 which can slide in the sliding groove 53, one side of the vertical rod 5 is connected with the cross rod 51, the cross rod 51 is provided with a gear, the cross rod 51 penetrates through the sliding sleeve 52 and is in sliding connection with the sliding sleeve 52, the fixed torque disc 4 is a gear, and the fixed torque disc 4 is in meshing connection with the gear provided on the cross rod 51. In order to ensure that the gear rack on the cross rod 51 is in meshing connection with the gear on the fixed torque disc 4, the sliding groove 53 is usually fixedly connected with the casting sand box 1.

[0059] The difference between the crank slider mechanism and the Scotch yoke lies in that the crank slider mechanism has a quick return characteristic and can make the torque acting on the vibrating rod 2 change unevenly, and the movement output curve of the Scotch yoke is always a sine function, and the Scotch yoke has better mechanical output performance.

[0060] In the embodiment, the motor 7 can drive the rotating disc 3 through the gearbox 6. In order to improve the stability of the meshing connection between the gear rack on the cross rod 51 and the gear on the fixed torque disc 4, the motor 7 and the gearbox 6 are usually placed on the vibrating table or are fixedly connected with the casting sand box 1.

[0061] Embodiment 2: The basic structure for solving the problem that the vacuum effect is limited in the existing lost foam vacuum pouring mode is to set a vacuum pipe on the sand box to perform vacuumizing, and the vacuumizing effect is mainly concentrated near the vacuum pipe. When the vacuum pipe is filled with casting sand, the vacuum cannot act on the casting sand at other positions, thereby causing the problem of limited vacuum effect.

[0062] The difference from the embodiment 1 lies in that:

[0063] The vibrating rod 2 is in a pipe structure, and has a cavity 22 in the pipe structure. The convex part 21 is provided with a through hole 211, and the through hole 211 is in communication with the cavity 22. The cavity 22 is used for vacuumizing.

[0064] In the embodiment, a filter core can be arranged in the through hole 211 to prevent the casting sand from entering the cavity 22.

[0065] Embodiment 3: The basic process for solving the problem that the existing lost foam is prone to produce carbonization defects is that the carbonization defects are mainly caused by the fact that the foam material contains carbon, free carbon is decomposed by burning of the foam during pouring, and the carbon invades the molten steel.

[0066] A lost foam precision casting process, comprising lost foam model 8 manufacturing, model coating, box embedding molding, vibrating, pouring, and comprising a casting vibrating device.

[0067] The model 8 can be a foam plastic model 8.

[0068] The coating thickness of the model coating is greater than 5mm, the model coating is a multilayer coating, the first layer of coating is a surface coating, the model 8 is heated after the model coating, so that the coating of the model 8 becomes a cavity with a smooth inner surface, and after heating, the original model 8 has been melted and disappeared, and the shell formed by the multilayer coating with the cavity serves as a new mold for pouring.

[0069] The coating is applied by immersion, and the model needs to be dried before each layer of coating is applied to ensure the strength of the coating, and the purpose of the coating thickness of the model coating being greater than 5mm is to form a shell with sufficient strength in the subsequent process.

[0070] The tamping includes the following steps:

[0071] S1.1: Place the casting sand box 1 on the tamping table;

[0072] S1.2: Put the model 8 into the casting sand box 1, and start filling the casting sand, and start the reciprocating mechanism during the filling of the casting sand, so that the reciprocating mechanism drives the vibration rod 2 to rotate back and forth through the constant torque structure, until the casting sand around the vibration rod 2 is tamped to the point where the reciprocating mechanism drives the constant torque structure to idle;

[0073] S1.3: After the casting sand is filled, prepare for the subsequent steps.

[0074] The pouring includes the following steps:

[0075] S2.1: Connect the vacuum device to the cavity 22 of the vibration rod 2 and start the vacuum device;

[0076] S2.2: Start pouring, and vibrate the casting sand box 1 during pouring, and maintain the vacuum degree in the cavity 22;

[0077] S2.3: After the pouring is completed, prepare for the subsequent steps.

[0078] In this embodiment, in order to improve the effect of vacuumizing, a plastic film can be used to seal the surface of the sand box 1.

[0079] In summary, the present application adopts the form of a vibration rod with a cavity penetrating through the sand box, and is matched with a constant torque and a reciprocating mechanism, which solves the problems that the existing lost foam model tamping method relies too much on experience, the degree of tamping effect cannot be quantified, and the existing lost foam vacuum pouring method is to set a vacuum pipe on the sand box to perform vacuumizing, the effect of vacuumizing is mainly concentrated near the vacuum pipe, and when the vacuum pipe is filled with casting sand, the vacuum cannot act on the casting sand at other positions, thereby causing the problem of limited vacuum effect.

[0080] It should be noted that in the description of the application, the terms "upper", "lower", "left", "right", "front", "back" and the like indicate the orientation or positional relationship of the structure of the application shown in the drawings, and are only for the convenience of describing the application simply, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application.

[0081] For "first" and "second" in the technical solution, it is only a call distinction for the same or similar structure, or the corresponding structure with similar function, not the arrangement of the importance of these structures, and has no order, or comparison size, or other meanings.

[0082] In addition, unless otherwise explicitly specified and limited, the terms "mounting", "connection" should be understood broadly, for example, the connection can be fixed connection, or detachable connection, or integrally connected; can be mechanical connection, or electrical connection; can be directly connected, or indirectly connected through intermediate medium, can be the communication inside two structures. For those skilled in the art, the specific meaning of the above terms in the application can be understood according to the general idea of the application and the specific situation of the present scheme.

Claims

1. A casting compacting device for compacting a casting sand box (1) for placing a pattern (8) and casting sand, comprising a vibrating rod (2) which penetrates the casting sand box (1) and is connected in rotation with the casting sand box (1) for vibrating the casting sand to compact it, the vibrating rod (2) being arranged in the casting sand box (1) in a position which is not easily compacted, characterized in that: The vibrating rod (2) is provided with a protrusion (21), and one end of the vibrating rod (2) is provided with a constant moment structure connected with the reciprocating mechanism. ​ The constant moment structure can prevent the reciprocating mechanism from continuously transmitting the moment to the vibrating rod (2) after the vibrating rod (2) is fixed.

2. A casting jolter as claimed in claim 1 wherein: The constant moment structure comprises a constant moment disc (4) sleeved on one end of the vibrating rod (2), a blind hole is formed on the inner side of the constant moment disc (4), a spring (42) is connected in the blind hole, the end of the spring (42) is connected with a sliding block (41), the sliding block (41) abuts against the surface of the vibrating rod (2), and the sliding block (41) can drive the vibrating rod (2) to rotate. When the moment acting on the constant moment disc (4) is too large, the constant moment disc (4) can rotate relative to the vibrating rod (2).

3. A casting jolter as claimed in claim 2 wherein: The reciprocating mechanism is one of a Scotch yoke and a slider-crank mechanism. When the reciprocating mechanism is the Scotch yoke, the reciprocating mechanism comprises a rotating disc (3), a vertical rod (5), a cross rod (51) and a sliding sleeve (52), a sliding groove (53) is formed on the vertical rod (5), a pin (31) is arranged on the rotating disc (3), the pin (31) can slide in the sliding groove (53), one side of the vertical rod (5) is connected with the cross rod (51), the cross rod (51) is provided with a tooth, the cross rod (51) penetrates through the sliding sleeve (52) and is connected with the sliding sleeve (52) in a sliding mode, the constant moment disc (4) is a gear, and the constant moment disc (4) is engaged with the tooth arranged on the cross rod (51).

4. A casting jolter as defined in claim 1 wherein: The vibrating rod (2) is in a tube structure and has a cavity (22) therein, a through hole (211) is formed in the protrusion (21), the through hole (211) is communicated with the cavity (22), and the cavity (22) is used for vacuumizing.

5. A casting jolter as claimed in claim 4 wherein: A filter element is arranged in the through hole (211).

6. A process for precision investment casting of a lost form comprising the steps of lost form pattern (8) making, pattern coating, flasking, jolting, pouring, characterized in that: The vibrating device comprises the casting device according to any one of claims 1-5. The vibrating device comprises the following steps: S1.1: placing the casting sand box (1) on the vibrating table; S1.2: placing the model (8) into the casting sand box (1) and starting to fill the casting sand, starting the reciprocating mechanism in the process of filling the casting sand, and driving the vibrating rod (2) to rotate back and forth through the constant moment structure, until the casting sand around the vibrating rod (2) is vibrated to the point that the reciprocating mechanism drives the constant moment structure to idle; S1.3: after the filling of the casting sand is completed, preparing for the subsequent steps.

7. A process according to claim 6, wherein: The pouring process comprises the following steps: S2.1: connecting the vacuumizing device with the cavity (22) of the vibrating rod (2) and starting the vacuumizing device; S2.2: starting the pouring, vibrating the casting sand box (1) and keeping the vacuum degree in the cavity (22) during the pouring process; S2.3: after the pouring is completed, preparing for the subsequent steps.

8. A process according to claim 6, wherein: The coating thickness of the model coating is greater than 5 mm.

9. A process according to claim 8, wherein: The model coating is a multilayer coating, and the first layer of coating is a surface coating.

10. A process according to claim 8, wherein: After the model coating, the model (8) is heated to form a cavity with a smooth inner surface.

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