Post-arrangement method of 3D printing sand core bar

Abstract

The invention relates to a postposition method of a 3D printing sand core bar, the core bar comprises a main bar and an auxiliary shell bar, the cross section of the main bar is elliptical, and the auxiliary shell bar is of a sheet structure with an arc-shaped cross section; the 3D printing sand core is provided with a core bar hole with a circular cross section; wrapping the short axial surface of the main rib with two auxiliary shell ribs, and inserting the auxiliary shell ribs and the main rib into the core rib hole together; and the main ribs are rotated, so that the auxiliary shell ribs abut against the inner wall of the core bar hole through the long axial surfaces of the main ribs. According to the method, the core bar is ingenious in structural design and simple in postposition operation, it can be guaranteed that the core bar can be easily inserted into the core bar hole through the difference of the long axis and the short axis of the oval main bar, after the main bar rotates, the auxiliary shell bar can abut against the inner wall of the core bar hole, and the strength of the sand core is improved. Meanwhile, due to the gap between the core bar hole and the short axial surface of the main bar, gas in the sand core can be exhausted through the gap, the effect of reinforcing the sand core is achieved, and the requirement for sand core exhaust can be met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of casting, in particular to a post-setting method of a 3D-printed sand core skeleton. BACKGROUND

[0002] In the traditional casting process, in order to increase the strength of the sand core with cantilever structure or slender rod structure, steel bars and the like are usually manually pre-embedded as the core skeleton during the core making process. After the sand hardens, the core skeleton is tightly combined with the sand core to form a firm whole, effectively preventing the sand core from being broken due to external force during transportation or damaged due to the action of molten metal buoyancy during pouring.

[0003] The 3D-printed sand core adopts additive manufacturing technology, and is directly formed by layer-by-layer laying of sand particles and spraying of a binder. This process breaks through the limitation of traditional core making on complex geometric shapes, and significantly improves the design freedom. In the 3D printing process, the core skeleton cannot be pre-embedded during printing, and can only be post-set in the sand core after printing. In the prior art, a core skeleton hole for inserting the core skeleton is arranged in the sand core, and then during the core assembly stage, mud glue is extruded into the hole, and the core skeleton is inserted, and the connection between the sand core and the core skeleton is realized after the mud glue is solidified.

[0004] This method has obvious quality problems. In order to ensure that the core skeleton is smoothly inserted, the core skeleton hole usually needs to be larger than the size of the core skeleton, and there is a gap between the two. If the gap is too large, it is easy to increase the filling amount of mud glue, and even because of the insufficient filling amount, the combination between the core skeleton and the sand core is not firm, and the bearing capacity is insufficient. Moreover, the excessive mud glue is difficult to dry completely, and gas is easy to be generated during high-temperature pouring, causing the "choking fire" defect. If the gap between the core skeleton hole and the core skeleton is reduced to reduce the filling amount of mud glue, the mud glue is difficult to flow into the pores, causing insufficient adhesion between the core skeleton and the sand core, and the effective connection strength between the core skeleton and the sand core cannot be established, resulting in failure of the core skeleton. The sand core is easy to crack under stress or thermal shock, and then causes casting defects such as molten metal drilling, choking fire, sand inclusion, and sand sticking. Therefore, how to post-set the core skeleton in the 3D-printed sand core has become a key technical problem that needs to be broken through at present. In addition, in the existing sand core casting process, a special exhaust hole needs to be arranged for sand core exhaust. SUMMARY

[0005] Therefore, it is necessary to provide a post-setting method of a 3D-printed sand core skeleton which can not only strengthen the sand core but also help the sand core exhaust.

[0006] In order to solve the above problems, the present application adopts the following technical scheme: The embodiment of the present application discloses a post-setting method of a 3D printed sand core skeleton, the skeleton comprises a main bone and an auxiliary shell bone, the cross section of the main bone is elliptical, and the auxiliary shell bone is a sheet structure with a circular arc cross section; the 3D printed sand core is provided with a skeleton hole with a circular cross section; two auxiliary shell bones are wrapped to the minor axis surface of the main bone, and the auxiliary shell bones and the main bone are inserted into the skeleton hole together; the main bone is rotated, so that the major axis surface of the main bone makes the auxiliary shell bones abut against the inner wall of the skeleton hole.

[0007] In one embodiment, the length of the minor axis of the main bone: the length of the major axis is 0.7-0.9:1.

[0008] In one embodiment, the diameter of the skeleton hole = the length of the major axis of the main bone + 2 x the thickness of the auxiliary shell bone.

[0009] In one embodiment, the major axis surface of the main bone is provided with an anti-skid structure.

[0010] In one embodiment, the anti-skid structure is a groove structure densely distributed.

[0011] In one embodiment, the rotation angle of the main bone is 90°.

[0012] In one embodiment, the main bone is a tubular structure.

[0013] In one embodiment, the circular arc angle of the auxiliary shell bone is 50°-70°.

[0014] In one embodiment, the skeleton hole is taken out together in the 3D printing process of the sand core.

[0015] In one embodiment, the main bone and the auxiliary shell bone are iron or steel.

[0016] The technical solution adopted by the present application can achieve the following beneficial effects: The post-setting method of the 3D printed sand core skeleton disclosed by the present application does not need to be filled and sealed between the skeleton and the skeleton hole, and eliminates the problem of fire inhalation caused by the incomplete drying of the mud glue. The post-setting method of the 3D printed sand core skeleton disclosed by the present application has a clever skeleton structure design and simple post-setting operation. Through the difference between the long and short axes of the elliptical main bone, the skeleton can be easily inserted into the skeleton hole, the auxiliary shell bone can be abutted against the inner wall of the skeleton hole after the main bone is rotated, and the strength of the sand core is improved. At the same time, due to the gap between the skeleton hole and the short axis surface of the main bone, the gas in the sand core can be discharged through the gap, which not only strengthens the sand core but also meets the sand core exhaust. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1Structure diagram of the first state of the core bone; Figure 2 Structure diagram of the second state of the core bone; Figure 3 Structure diagram of the sand core; Figure 4 Cross-sectional view of Figure 3 ; Figure 5 Structure diagram of the sand core in another state; Figure 6 Cross-sectional view of Figure 5 .

[0018] BRIEF DESCRIPTION OF DRAWINGS 100 - main bone, 110 - long axis surface, 120 - short axis surface; 200 - auxiliary shell bone; 300 - sand core, 310 - cantilever structure, 320 - core bone hole. DETAILED DESCRIPTION

[0019] In order to facilitate the understanding of the present application, a more complete description of the present application will be provided below with reference to the relevant drawings. The preferred embodiments of the present application are shown in the drawings. However, the present application 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 application more thorough and comprehensive.

[0020] It should be noted that when an element is referred to as "provided on" another element, it can be directly on the other element or there can be a middle element. When an element is referred to as "connected to" another element, it can be directly connected to the other element or there can be a middle element. The terms "vertical", "horizontal", "left", "right", "top", "bottom", "bottom end", "top end" and the like used herein are for illustrative purposes only and are not intended to be the only implementation.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used in the specification of the present application herein are only for the purpose of describing the specific embodiments and are not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more of the associated listed items.

[0022] The embodiments of the present application disclose a post-processing method of a 3D printed sand core core bone, such as Figure 1 , Figure 2As shown, the post-processing method of the 3D printed sand core skeleton disclosed in the embodiments of the present application designs a 3D printed sand core post-processing skeleton without using mud glue to fill the gap, which can include a main skeleton 100 and two auxiliary shell bones 200. Wherein, the main skeleton 100 is a rod-shaped structure with an elliptical cross section, and the auxiliary shell bone 200 is a sheet-shaped structure with a circular arc cross section. The skeleton includes two states of the first state and the second state, and the first state is as shown in Figure 1 As shown, the two auxiliary shell bones 200 are respectively wrapped on the outer side of the two short axis surfaces 120 of the main skeleton 100, that is, the skeleton is in a non-working state; the second state is as shown in Figure 2 As shown, the two auxiliary shell bones 200 are respectively arranged on the outer side of the two long axis surfaces 110 of the main skeleton 100, and the auxiliary shell bone 200 is opened by the long axis surface 110 of the main skeleton 100, that is, the skeleton is in a working state. The main skeleton 100 and the auxiliary shell bone 200 can be iron or steel.

[0023] As shown in Figures 3 to 6 The sand core 300 in the embodiment has a cantilever structure 310, which is a weak part of the sand core 300 and is easy to break and damage, so the sand core 300 needs to be post-processed with a skeleton. The sand core 300 can be provided with a skeleton hole 320 for post-processing the skeleton. The design content of the skeleton hole 320 is added in the 3D printing process design of the sand core 300, and the skeleton hole 320 can be taken out synchronously in the 3D printing process of the sand core 300 and exposed after sanding.

[0024] In the embodiments disclosed in the present application, the skeleton is inserted into the skeleton hole 320 in two steps. As shown in Figure 3 、 Figure 4 The two auxiliary shell bones 200 are respectively wrapped on the outer side of the two short axis surfaces 120 of the main skeleton 100, so that the skeleton is in a non-working state, and the size of the skeleton is smaller than that of the skeleton hole 320. The skeleton can be easily inserted into the skeleton hole 320. When the skeleton is inserted into the skeleton hole 320, there is a gap between the long axis surface 110 of the main skeleton 100 and the skeleton hole 320, and there is also a gap between the auxiliary shell bone 200 on the outer side of the short axis surface 120 of the main skeleton 100 and the skeleton hole 320. The second step is as shown in Figure 5 、 Figure 6As shown, the position of the auxiliary shell bone 200 in the core bone hole 320 remains unchanged, the main bone 100 is manually rotated around its center by 90° or so, the long axis surface 110 of the main bone 100 props open the auxiliary shell bone 200, and the auxiliary shell bone 200 is compacted against the inner wall of the core bone hole 320. At this time, the core bone is in the working state, the long axis surface 110 of the main bone 100 and the auxiliary shell bone 200 are jointly supported in the inside of the cantilever structure 310 of the sand core 300, and the cantilever structure 310 is enhanced. In addition, when the core bone is in the working state, there is a gap between the short axis surface 120 of the main bone 100 and the core bone hole 320, which can be used for exhaust of the sand core 300 during pouring, and the sand core 300 can improve the casting quality without additionally setting exhaust holes.

[0025] In the disclosed embodiment, the structures and sizes of the main bone 100, the auxiliary shell bone 200 and the core bone hole 320 should be matched with each other. The core bone hole 320 can be a hole with a circular cross section, and the diameter thereof should be equal to the sum of the length of the long axis of the main bone 100 and the thickness of the two auxiliary shell bones 200, i.e. the diameter of the core bone hole 320 = the length of the long axis of the main bone 100 + 2 x the thickness of the auxiliary shell bone 200. The length of the main bone 100 should be greater than the hole depth of the core bone hole 320 and / or the length of the auxiliary shell bone 200, so as to facilitate the rotation operation of the main bone 100. Further, the outer end of the main bone 100 can be further provided with an auxiliary structure facilitating the rotation operation, such as a hand holding part, a one-character-shaped or cross-shaped groove, etc. The length of the short axis of the main bone 100 can be 0.7-0.9 times, preferably 0.8 times, the length of the long axis. The thickness of the auxiliary shell bone 200 is preferably 1 mm.

[0026] In the disclosed embodiment, the long axis surface 110 of the main bone 100 can be provided with an anti-skid structure, so as to facilitate the core bone to remain in the working state in the sand core 300. During the transportation, core assembly and pouring of the sand core 300, the anti-skid structure can prevent the main bone 100 from sliding and failing, so that the long axis surface 110 of the main bone 100 remains to prop open the auxiliary shell bone 200 and compact the auxiliary shell bone 200 against the inner wall of the core bone hole 320; the core bone remains in the working state, and the long axis surface 110 of the main bone 100 and the auxiliary shell bone 200 are jointly supported in the inside of the cantilever structure 310 of the sand core 300, thereby enhancing the cantilever structure 310. Further, the anti-skid structure can be a groove structure provided on the surface of the long axis surface 110 and uniformly and densely distributed, and the groove depth of the groove structure is preferably 1 mm.

[0027] In the disclosed embodiment, as shown in Figure 1 , Figure 3 When the core bone is in the non-working state, the two auxiliary shell bones 200 are respectively wrapped on the outer sides of the two short axis surfaces 120 of the main bone 100, and the wrapping amount of each auxiliary shell bone 200 on the short axis surface 120 of the main bone 100, measured by the angle of the short axis surface 120, can be 50°-70°, and the optimal value is 60°.

[0028] In one optional embodiment of the present invention, the main skeleton 100 can be a tubular structure, which can reduce the weight of the core skeleton and increase the air venting of the sand core 300. The cross-sectional shape of the main skeleton 100 is still elliptical to facilitate rotational transition between working and non-working states, and the inner tube shape of its cross-section can be either elliptical or circular.

[0029] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for post-processing 3D-printed sand core skeletons, characterized in that, The core bone includes a main bone and an auxiliary shell bone. The main bone has an elliptical cross-section, and the auxiliary shell bone is a sheet-like structure with an arc-shaped cross-section. The 3D printed sand core is provided with a core hole with a circular cross-section; The two auxiliary shell bones are wrapped around the short axis surface of the main bone, and the auxiliary shell bones and the main bone are inserted together into the core bone hole; Rotate the main bone so that the long axis of the main bone presses the auxiliary shell bone against the inner wall of the core bone hole.

2. The method for post-installation of 3D printed sand core according to claim 1, characterized in that, The ratio of the minor axis length to the major axis length of the main bone is 0.7 to 0.9:

1.

3. The method for post-installation of 3D printed sand core according to claim 2, characterized in that, The diameter of the core bone hole = the long axis length of the main bone + 2 × the thickness of the auxiliary shell bone.

4. The method for post-installation of 3D printed sand core according to claim 3, characterized in that, The long axis surface of the main bone is provided with an anti-slip structure.

5. The method for post-installation of 3D printed sand core according to claim 4, characterized in that, The anti-slip structure is a densely distributed groove structure.

6. The method for post-installation of 3D printed sand core according to claim 1, characterized in that, The rotation angle of the main bone is 90°.

7. The method for post-installation of 3D printed sand core according to claim 1, characterized in that, The main bone is a tubular structure.

8. The method for post-installation of 3D printed sand core according to claim 1, characterized in that, The arc angle of the auxiliary shell is 50° to 70°.

9. The method for post-installation of 3D printed sand core according to claim 1, characterized in that, The core hole is brought out along with the sand core during the 3D printing process.

10. The method for post-installation of 3D printed sand core according to any one of claims 1 to 9, characterized in that, The main skeleton and the auxiliary shell skeleton are made of iron or steel.

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