CN109648043B

CN109648043B - Anti-cracking method for slender sand core

Info

Publication number: CN109648043B
Application number: CN201910029056.2A
Authority: CN
Inventors: 程行东; 刘利平
Original assignee: Kocel Machinery Co Ltd
Current assignee: Kocel Machinery Co Ltd
Priority date: 2019-01-12
Filing date: 2019-01-12
Publication date: 2020-11-10
Anticipated expiration: 2039-01-12
Also published as: CN109648043A

Abstract

An anti-cracking method for a slender sand core belongs to the technical field of casting and is used for solving the problems of casting air holes, meat deficiency, leakage and the like caused in the casting process after the sand core cracks, and the anti-cracking method comprises the following steps: 1) selecting a gray cast iron material with small normal-temperature plastic deformation and low high-temperature elongation to manufacture the core iron for the slender sand core; 2) making a slender sand core by using quicksand; 3) horizontally placing the prepared slender sand core on a supporting platform in a multipoint supporting mode, and brushing non-water or little-water refractory coatings such as alcohol-based coatings and the like; 4) naturally airing the refractory coating brushed on the slender sand core in a shade drying mode; 5) and transferring the dried slender sand core to a stock area for vertical storage. The anti-cracking method solves the problems of cracks and deformation of the slender sand core by adopting the core iron without plastic deformation and adopting the sand core drying method of drying in the shade, thereby avoiding the problems of casting air holes, meat deficiency, leakage and the like caused by the cracks of the sand core.

Description

Anti-cracking method for slender sand core

Technical Field

The invention relates to the technical field of casting, in particular to an anti-cracking method for a casting sand core.

Background

An engine frame casting is usually integrated with a crankshaft seat, a cylinder sleeve, an air cavity, a water pipe and an oil pipe, a long and thin water pipe and an oil pipe sand core of a large engine frame casting are flatly placed and supported at multiple points after a steel core iron core is used for coating paint, the long and thin sand core is subjected to condensation polymerization reaction and is gradually dehydrated and generates micro shrinkage in the continuous placing and transferring process of the sand core, the steel core iron is not shrunk at normal temperature, the core iron is thin and easy to bend, so that the long and thin sand core generates micro cracks and gradually expands, the core is placed in the next day, the cracks expand, and the cracked sand core generates pyrolysis gas in the heating process of high-temperature molten metal and easily enters the molten metal through the cracks of the sand core, so that the molten metal is boiled to generate choking and air holes, and.

Disclosure of Invention

In view of the problems of the standard exceeding of the size of the casting caused by the deformation of the elongated sand core, the air holes and the meat deficiency of the casting caused by the cracks, and the like, the anti-cracking method of the elongated sand core is needed to be provided, and the problems of the cracks and the deformation of the elongated sand core are solved by adopting the core iron without plastic deformation and the sand core drying method by drying in the shade, so that the problems of the air holes, the meat deficiency, the leakage and the like of the casting caused by the cracks of the sand core are solved.

A method of cracking an elongated sand core comprising the steps of:

1) selecting a gray cast iron material with small normal-temperature plastic deformation and low high-temperature elongation to manufacture the core iron for the slender sand core;

2) making a slender sand core by using quicksand;

3) horizontally placing the prepared slender sand core on a supporting platform in a multipoint supporting mode, and brushing non-water or little-water refractory coatings such as alcohol-based coatings and the like;

4) naturally airing the refractory coating brushed on the slender sand core in a shade drying mode;

5) and transferring the dried slender sand core to a stock area for vertical storage for later use.

Preferably, a clamping device of the elongated sand core is arranged in the stock area, the clamping device is provided with a clamping part and a fixing part, and the clamping part is used for clamping the elongated sand core; the fixing part is used for fixing the clamping device on the upright post, so that the vertical storage of the slender sand core is realized. The fixing part is made of two flat plates with certain width and rigidity, through holes are formed in the two ends of each flat plate, and the two flat plates are tightly clamped through bolts, so that the fixing part is locked on the stand column. The clamping part is arranged on the fixing part and is made of two short plates with the width identical to that of the flat plate of the fixing part, one end of each short plate is fixedly connected to one side face of the flat plate, a plurality of clamping grooves are symmetrically formed in the other end of each short plate, and baffles are arranged in the clamping grooves, so that the long and thin sand cores are clamped.

The technical scheme of the invention has the beneficial effects that: the deformation of the slender sand core is reduced by adopting the core iron with small deformation at normal temperature, so that the risks of deformation and cracking of the sand core are reduced; by adopting the use of the less-water refractory coating, the cracking of the sand core caused by high-temperature drying is avoided; and the deformation of the core iron in the length direction is further reduced by vertically placing the slender sand core, namely the core iron is prevented from freely stretching in the length direction under the action of the self gravity of the core iron and the gravity of the externally wrapped core sand, so that the cracking of the sand core and the bending deformation caused by horizontal placement are avoided. Finally, the problems of casting air holes, meat deficiency, leakage and the like caused by the cracking of the sand core are avoided.

Drawings

FIG. 1 is a schematic view of a core iron structure;

FIG. 2 is a schematic three-dimensional structure of the clamping device;

FIG. 3 is a schematic view showing the engagement of the clamping device with the column;

FIG. 4 is a front view of the clamping device in use;

FIG. 5 is a schematic side view of the clamping device in use;

in the drawings, 1-a clamping device; 101-a stationary part; 102-a clamping portion; 2-upright post; 3-a slim sand core; 301-core print pad.

Detailed Description

In order to more clearly illustrate the technical solution of the present invention, the detailed description will be given according to the embodiments of the drawings, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art that other structural forms or combinations can be obtained according to the drawings without creative efforts.

The technical scheme of the invention is specifically elaborated by taking the production of a slender sand core with the width of 60-800 mm, the height of 60-800 mm and the length of 2000-3000 mm as an example, namely the ratio of the width (height) to the length of the slender sand core is not more than 1: 10.

The casting process steps for producing the elongated sand core comprise the following steps:

1) selecting a gray cast iron material with small normal-temperature plastic deformation and low high-temperature elongation to manufacture the core iron for the slender sand core, wherein the length of the core iron is equal to or less than that of the slender sand core;

2) making a slender sand core 3 by using quicksand;

3) horizontally placing the prepared slender sand core 3 on a supporting platform in a multipoint supporting mode (namely horizontally placing), and brushing or dip-coating alcohol-based refractory paint, or applying the alcohol-based refractory paint on the surface of the slender sand core;

4) because the volatility of the alcohol-based coating is stronger, the alcohol-based refractory coating brushed on the slender sand core 3 can be naturally aired directly in a drying mode; by adopting a natural drying mode of drying in the shade, the cracking of the elongated sand core 3 caused by the sudden heating of the surface of the sand core in an ignition drying mode is avoided;

5) and (3) transferring the dried elongated sand core 3 to an area where the clamping device 1 can be fixed, such as an upright column 2 at a corner of a workshop or a specially-established stock area, and vertically storing the elongated sand core 3 for later use.

When the upright column 2 at one free corner of the workshop is used as a fixed upright column of the clamping device 1, the length of the flat plate of the fixed part 101 is larger than the width of the upright column 2, and meanwhile, it is required to ensure that through holes at two ends of the flat plate are not shielded by the upright column 2, namely, the width of the upright column 2 is smaller than the length of the flat plate between the through holes; in order to ensure the strength of the flat plate, steel plates with the thickness of 3-6 mm and the width of 100-150 mm are selected to be made into the flat plate, when the flat plate is used specifically, the two flat plates are arranged on two sides of an upright post 2 and are locked by bolts, so that the clamping device 1 is matched with the upright post 2, and the height of the clamping device 1 on the upright post 2 is required to be ensured to be three quarters of the length of the long and thin sand core 3, or one end of the long and thin sand core 3 is enabled to be on the ground and started from the ground, and the clamping device 1 is arranged at a position which is about three quarters of the length of the long and thin sand core 3. Further, in order to ensure that the core print of the elongated sand core 3 contacting the ground is not damaged, a core print cushion block 301 is further arranged between the ground and the core print of the elongated sand core 3 contacting the ground, the outer periphery of the core print cushion block 301 is a wooden square box, and the shape of the inner periphery structure of the core print cushion block is the same as that of the outer periphery structure of the core print of the elongated sand core 3, so that the protection of the core print of the elongated sand core 3 is realized. When a dedicated stock area of the elongated sand cores 3 is provided, the length of the fixing portions 101 can be matched with each other according to the width of the fixing posts 2 provided in the stock area.

The clamping part 102 is arranged on one side surface of any one flat plate of the fixing part 101, the clamping part 102 is composed of two short plates with the same structure and a baffle, one end of each short plate is connected to one side surface of the flat plate, the other end of each short plate is provided with a clamping groove, the clamping grooves are matched with the baffle, and a plurality of groups of clamping grooves are symmetrically arranged on one group of short plates; meanwhile, a plurality of groups of the clamping parts 102 are arranged in the length direction of the fixing part 101, so that one clamping device 1 can clamp a plurality of slender sand cores 3, and the space and the using amount of the clamping device 1 are saved. Further, in order to improve the connection firmness between the clamping portion 102 and the fixing portion 101, the width of the short plate of the clamping portion 102 may be equal to the width of the flat plate of the fixing portion 101. Furthermore, the depth of the clamping grooves is about one third of the width of the short plate, and a plurality of groups of symmetrical clamping grooves are distributed in the length direction of the short plate at equal intervals or unequal intervals, so that the clamping device is suitable for clamping the slender sand cores 3 with different heights. Preferably, in order to prevent the baffle from falling off, two ends of the baffle can be bent at a certain angle, or the baffle can be set to be of a C-shaped structure; meanwhile, the width of the baffle is larger than the depth of the clamping groove, so that the baffle is convenient to install and take out.

When the long and thin sand core 3 is clamped by the clamping device 1, in order to avoid the clamping part 102 from damaging the long and thin sand core 3, rubber pads are arranged on the surfaces of the clamping part 102, which are contacted with the long and thin sand core 3, so that the long and thin sand core 3 can be clamped and the long and thin sand core 3 can be prevented from being damaged.

The above embodiment is only a description of a typical application of the technical solution of the present invention, and may be reasonably expanded without creative efforts.

Claims

1. A method for preventing cracking of a slender sand core, which comprises the following steps,

selecting gray cast iron to manufacture core iron for the slender sand core;

horizontally placing the prepared slender sand core on a supporting platform in a multi-point supporting mode, and brushing a non-water-quality or less-water refractory coating which is an alcohol-based coating;

naturally airing the refractory coating applied to the surface of the slender sand core in a shade drying mode;

transferring the dried slender sand core to a stock area for vertical storage, wherein the slender sand core is vertically stored through a clamping device;

the clamping device is characterized by comprising a clamping part and a fixing part, wherein the clamping part is used for clamping the slender sand core, and the fixing part is used for locking and clamping the clamping device on an upright post; the fixing part is made of two flat plates with certain width and rigidity, through holes are formed in the two ends of each flat plate, and the two flat plates are tightly clamped on the stand columns through bolts; the height of the fixing part from the ground is three quarters of the length of the slender sand core; the clamping part is arranged on one side face of any one flat plate of the fixing part, the clamping part is composed of two short plates with the same structure and a baffle, one end of each short plate is connected to one side face of the flat plate, the other end of each short plate is provided with a clamping groove, and the clamping grooves are matched with the baffle.

2. The method of preventing cracking of an elongated sand core according to claim 1, wherein the plate has a thickness of 3mm to 6mm and a width of 100mm to 150 mm.

3. The method of cracking a tall and slender sand core as claimed in claim 1, wherein said slots are arranged in groups along the length of the slab.

4. The method of cracking a slender core as claimed in claim 3, wherein said clamping portions are provided in groups in the length direction of said fixing portion.

5. A method of preventing cracking of an elongated sand core as claimed in any one of claims 1 to 4, characterised in that a core block is also provided between the core head of the elongated sand core and the ground.