A method for making a sand core for casting

Abstract

The present invention relates to a core making method for a sand core for casting, wherein the sand core for casting comprises a sand core body and a sand core in a chilled iron region. The sand core body is cored by 3D printing, and there is no need to consider the demoulding and material removal problems, and one-time high-precision printing of sand cores of various complex structures can be achieved. The core making process of the sand core in the chilled iron region comprises the following steps: installing a panel on the sand core body, and arranging a number of chills in the panel; filling resin sand in the panel, and after the resin sand is solidified, removing the panel, and solidifying and forming the chill, the sand core in the chilled iron region, and the sand core body by manual core making. The chill and the sand core structure are flush without steps, and the cast casting does not need to be polished and shaped. The core making method for the sand core for casting disclosed in the present invention avoids the use of adhesive to post-place the chill, and the compact sand filling ensures that there is no seam between the chill and the sand core, effectively preventing the chill from falling off and the formation of defects such as choking and pores during the pouring process.

Description

Technical Field

[0001] The invention relates to the technical field of casting, in particular to a method for making a sand core for casting. Background Art

[0002] With the promotion and application of 3D printing technology, the method of using 3D printed sand cores for casting production has gradually been applied in the industry. 3D printed sand cores are solidified by using liquid connectors to create three-dimensional solid prototypes. Chills cannot be placed during the 3D printing sand core process. The conventional solution is to design a chiller groove where the chiller is needed when designing the 3D printing sand core casting process. After the sand core is printed, the chiller is bonded to the chiller groove.

[0003] During the transportation and use of the sand core, the chill is at risk of falling off due to the weak bonding of the chill under the action of gravity. After repeated use, the chill has dimensional errors, and the chill cannot be placed in the chill slot, which increases the difficulty of on-site operation, or the chill can be placed in the chill slot but the gap between it and the chill slot is too large, resulting in casting defects. In addition, when glue is used to bond the chill, the molten iron reacts with the glue during the pouring process to produce gas, causing porosity-type quality defects in the casting around the chill. Summary of the invention

[0004] Based on this, it is necessary to provide a core making method for casting sand cores without bonding chillers to address technical problems such as poor bonding of post-printed chillers, deformation of chillers, and reaction of bonding glue with molten iron.

[0005] In order to solve the above problems, the present invention adopts the following technical solutions:

[0006] An embodiment of the present invention discloses a core making method for a sand core for casting, wherein the sand core for casting comprises a sand core body and a sand core in a cold iron area, wherein the sand core body is core-made by 3D printing; the core making method for the sand core in the cold iron area comprises the following steps: installing a surrounding plate on the sand core body, and arranging a plurality of cold irons in the surrounding plate; filling the surrounding plate with resin sand, and removing the surrounding plate after the resin sand is solidified.

[0007] In one of the embodiments, a first mounting portion matching the enclosure is provided on the sand core body, and is used to mount the enclosure to the sand core body; the first mounting portion and the sand core body are printed and formed integrally.

[0008] In one of the embodiments, a second mounting portion matching the chiller is provided on the sand core body for mounting the chiller on the sand core body; the second mounting portion is integrally printed with the sand core body.

[0009] In one of the embodiments, a positioning piece is provided on the sand core body for positioning the chiller; the positioning piece is integrally printed with the sand core body.

[0010] In one embodiment, a plurality of sand hanging pieces are provided on the non-working surface of the chiller.

[0011] In one embodiment, the cross-section of the cold iron gradually increases from the outer wall to the inner wall of the enclosure.

[0012] In one embodiment, a plurality of connectors are provided at the joint between the sand core body and the cold iron region sand core.

[0013] In one of the embodiments, the connecting piece is a groove and / or a boss arranged on the sand core body, and the groove and / or the boss are printed and formed integrally with the sand core body; when resin sand is filled in the enclosure, resin sand is also filled in the groove and / or around the boss.

[0014] In one embodiment, the resin sand is a mixture of casting sand, resin and curing agent.

[0015] In one embodiment, the curing time of the resin sand is 5 minutes to 10 minutes.

[0016] The technical solution adopted by the present invention can achieve the following beneficial effects:

[0017] The core making method of the sand core for casting disclosed by the present invention adopts 3D printing to make the core of the sand core body, and there is no need to consider the demoulding and material removal problems. It can realize one-time high-precision printing of sand cores with various complex structures, greatly improving the flexibility of casting process design; the chill, the sand core in the chill area and the sand core body are solidified and formed by manual core making. The chill and the sand core structure are flush without steps, and the cast casting does not need to be polished and shaped. The core making method of the sand core for casting disclosed by the present invention avoids the use of adhesive to post-place the chill, and the compact sand filling ensures that there is no gap between the chill and the sand core, effectively preventing the chill from falling off and the formation of defects such as choking and air holes during casting. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A top view of a casting sand core made by the core making method disclosed in an embodiment of the present invention;

[0019] Figure 2 for Figure 1 A cross-sectional view of

[0020] Figure 3 It is a top view of the core making state of the sand core in the chill area;

[0021] Figure 4 for Figure 3 A cross-sectional view of

[0022] Description of reference numerals:

[0023] 100 - sand core body, 110 - first mounting portion, 120 - second mounting portion, 131 - groove, 132 - boss;

[0024] 200-hoarding;

[0025] 300-cold iron, 310-sand hanging parts;

[0026] 400-Cold iron area sand core. DETAILED DESCRIPTION

[0027] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly understood.

[0028] It should be noted that when an element is referred to as being "disposed on" another element, it may be directly on the other element or there may be a centered element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a centered element at the same time. The terms "vertical", "horizontal", "left", "right", "top", "bottom", "bottom end", "top end" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0030] The embodiment of the present invention discloses a method for making a sand core for casting, such as Figure 1 , Figure 2As shown, the casting sand core may include a sand core body 100 and a cold iron region sand core 400. The sand core body 100 may be made by 3D printing, without considering the demoulding and material removal issues, and may realize one-time high-precision printing of sand cores of various complex structures, greatly improving the flexibility of casting process design. After the sand core body 100 is printed, the cold iron region sand core 400 may be made by manual method with the sand core body 100 as the base. During the manual core making, the cold iron 300, the cold iron region sand core 400 and the sand core body 100 may be solidified and formed into one body.

[0031] Specifically, the core making method of the casting sand core disclosed in the embodiment of the present invention may include the following steps:

[0032] S01. Design the structure of the sand core body 100 and import the design data into the 3D printer.

[0033] S02, using a 3D printer to print the sand core body 100, and cleaning the loose sand on the sand core body 100.

[0034] S03, such as Figure 3 , Figure 4 As shown, a surrounding plate 200 is installed on the sand core body 100 , and the surrounding plate 200 and the sand core body 100 together form a receiving cavity.

[0035] It should be noted that the enclosure 200 may be an integral structure or may be formed by splicing a number of panels, and the embodiment of the present invention does not impose any specific limitation on this.

[0036] S04. Place a number of chillers 300 in the accommodating cavity as required.

[0037] S05. Fill the containing cavity with resin sand, compact it and scrape it flat.

[0038] S06, after the resin sand in the accommodating cavity is solidified, the enclosure 200 is removed, and the following is obtained: Figure 1 , Figure 2 Sand core for casting shown.

[0039] S06. Applying a casting coating on the casting sand core.

[0040] The cold iron 300 is arranged in the cold iron area sand core 400, which can effectively control the solidification order of the molten metal during the pouring process and prevent defects such as shrinkage and shrinkage cavities in the casting. There is no seam between the cold iron 300 and the cold iron area sand core 400, and the cold iron 300, the cold iron area sand core 400 and the sand core body 100 can be integrally formed without using adhesive, thereby ensuring the strength and hardness of the entire sand core, and effectively preventing the cold iron from falling off and the formation of defects such as choking and pores during pouring. The core making method of the casting sand core disclosed in the embodiment of the present invention is simple and easy to operate, and is conducive to on-site operations; it solves the problem that the cold iron of the 3D printed sand core is difficult to set, and the cold iron 300 and the enclosure 200 can be recycled and reused, effectively reducing the production cost.

[0041] In an optional embodiment disclosed in the present invention, in step S04, a chill 300 is disposed on the inner wall of the enclosure 200. After core making is completed, at least one side of the chill 300 is flush with the surface of the sand core, and the chill 300 acts as a direct cooling chill during the casting process.

[0042] In another optional embodiment disclosed in the present invention, in step S04, the chill 300 is disposed in the accommodating cavity, and a certain distance is provided between the chill 300 and the inner wall of the enclosure 200. After the core making is completed, the chill 300 is placed in the sand core to serve as a sand-isolating chill in the casting process. Of course, the distance between the chill 300 and the inner wall of the enclosure 200 can be arbitrarily designed according to the casting process requirements, and the embodiment of the present invention does not impose specific restrictions on this.

[0043] In the embodiments disclosed in the present invention, in step S01, a first mounting portion 110 matching the enclosure 200 can also be designed for installation positioning and limiting of the enclosure 200; in step S02, the first mounting portion 110 and the sand core body 100 are printed integrally; the first mounting portion 110 can be a mounting boss, a mounting groove, etc., as long as it matches the enclosure 200; preferably, it is a mounting groove. In step S06, after removing the enclosure 200, resin sand can be filled in the mounting groove. After the resin sand is solidified, the traces of the first mounting portion are eliminated, thereby reducing the amount of later processing of the casting.

[0044] In the embodiment disclosed in the present invention, in step S01, a second mounting portion 120 matching the cold iron 300 can also be designed for installation positioning and limiting of the cold iron 300; in step S02, the second mounting portion 120 and the sand core body 100 are printed integrally; the second mounting portion 120 can be a mounting boss, a mounting groove, etc., as long as it matches the cold iron 300.

[0045] Furthermore, in step S01, a positioning mark (not shown in the figure) can also be designed, and correspondingly, a corresponding positioning mark is also set on the cold iron; in step S02, the positioning mark can be printed integrally with the sand core body 100, and when preventing the cold iron 300, the positioning mark can assist the second mounting part 120 in installation and positioning.

[0046] In the embodiment disclosed in the present invention, a plurality of sand hanging pieces 310 may be provided on the chill 300 to reliably connect the chill 300 with the sand core and improve the stability of the chill 300 in the sand core. It should be noted that for the straight-cooled chill, the sand hanging pieces 310 should be provided on the non-working surface of the chill 300; during casting, the surface of the chill located on the cavity surface should maintain its flatness.

[0047] In the embodiments disclosed in the present invention, the shape of the chill 300 can be arbitrarily designed according to the shape of the casting and the casting process requirements. Preferably, the chill 300 can be an inverted slightly shaped casting (not shown) with a cross-sectional area increasing from the outer wall to the inner wall of the enclosure 200, so as to prevent the chill 300 from falling off the sand core during the transportation and use of the sand core.

[0048] In the embodiments disclosed in the present invention, in order to increase the connection reliability between the sand core body 100 and the cold iron area sand core 400, a number of connectors can be arranged between the two. For example, in step S01, a groove 131 can be arranged on the side of the sand core body 100 facing the bonding surface of the sand core body 100 and the cold iron area sand core 400; in step S02, the groove 131 can be printed and formed integrally with the sand core body 100; in step S05, resin sand can be filled into the groove 131 and compacted at the same time when filling sand, and after the resin sand is solidified, a connecting boss that fits tightly with the groove 131 is formed in the groove 131, and the connection reliability between the sand core body 100 and the cold iron area sand core 400 is increased by the connection boss and the groove 131. Preferably, the groove 131 can be a stepped groove. Optimally, the groove 131 includes a large end and a small end, wherein the small end is arranged at the end thereof away from the cold iron region sand core 400, and the large end is arranged at the end thereof facing the cold iron region sand core 400, so as to facilitate the smooth implementation of the sand filling and compacting steps in the groove 131. For another example, in step S01, a boss 132 may be arranged on the side of the joining surface of the sand core body 100 and the cold iron region sand core 400 facing the cold iron region sand core 400; in step S02, the boss 132 may be integrally printed with the sand core body 100; after the sand filling in step S05, a connecting groove that closely matches the boss 132 is formed in the cold iron region sand core 400 after the resin sand is cured, and the connection reliability between the sand core body 100 and the cold iron region sand core 400 is increased by the cooperation between the connecting groove and the boss 132. Preferably, the boss 132 may be stepped. Optimally, the boss 132 may include a large end and a small end, wherein the small end is disposed at one end thereof facing the sand core body 100 and the large end is disposed at one end thereof facing the cold iron region sand core 400, so as to facilitate the limiting connection between the boss 132 and the connecting groove.

[0049] In the embodiments disclosed in the present invention, any of the resin sands described above may be formed by uniformly mixing molding sand for casting with resin and curing agent to achieve dual-component curing of the cold iron region sand core 400. Furthermore, the curing time of the resin sand may be 5 to 10 minutes, that is, the waiting time between steps S05 and S06 may be 5 to 10 minutes.

[0050] According to the sand core making method for casting sand core disclosed in the embodiment of the present invention, there is no gap between the chill and the sand core, and the chill and the cavity can be completely isolated after the coating is applied. After pouring, the chill will not be wrapped by the molten metal and will automatically fall off during cleaning, so there is no need to clean the chill.

[0051] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for making a sand core for casting, characterized in that: The casting sand core comprises a sand core body and a cold iron region sand core, wherein the sand core body is made by 3D printing; and the making process of the cold iron region sand core comprises the following steps: A shroud is installed on the sand core body, and a plurality of chillers are arranged in the shroud; Filling the enclosure with resin sand, and removing the enclosure after the resin sand is solidified; The sand core body is provided with a first mounting portion matching the enclosure plate, and used for mounting the enclosure plate on the sand core body; the first mounting portion and the sand core body are integrally printed and formed; The first mounting portion is a mounting groove, and resin sand is filled into the mounting groove after the enclosure is removed; The joint between the sand core body and the cold iron area sand core is provided with a plurality of connecting pieces; The connecting piece is a groove and / or a boss arranged on the sand core body, and the groove and / or the boss are integrally printed and formed with the sand core body; when the resin sand is filled into the enclosure, the resin sand is also filled into the groove and / or around the boss; The groove is a stepped groove, the groove includes a large end and a small end, the small end of the groove is arranged at the end of the groove away from the sand core in the cold iron area, and the large end of the groove is arranged at the end of the groove facing the sand core in the cold iron area; the boss is stepped, the boss includes a large end and a small end, the small end of the boss is arranged at the end of the boss facing the sand core body, and the large end of the boss is arranged at the end of the boss facing the sand core in the cold iron area.

2. The method for making a casting sand core according to claim 1, characterized in that: A second mounting portion matching the chiller is provided on the sand core body and is used to mount the chiller on the sand core body; the second mounting portion is integrally printed with the sand core body.

3. The method for making a casting sand core according to claim 2, characterized in that: A positioning piece is arranged on the sand core body for positioning the cold iron; the positioning piece and the sand core body are integrally printed and formed.

4. The method for making a casting sand core according to claim 1, characterized in that: The non-working surface of the chiller is provided with a plurality of sand hanging pieces.

5. The method for making a casting sand core according to claim 1, characterized in that: The cross section of the cold iron gradually increases from the outer wall to the inner wall of the enclosure.

6. The method for making a casting sand core according to any one of claims 1 to 5, characterized in that: The resin sand is a mixture of casting sand, resin and curing agent.

7. The method for making a casting sand core according to claim 6, characterized in that: The curing time of the resin sand is 5 to 10 minutes.

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