CN217647436U - Positioning structure for improving size precision of sand core produced by sand lined iron mold - Google Patents

Abstract

The utility model provides an improve sand-lined metal mold production psammitolite size precision's location structure includes psammitolite body and core print, and psammitolite body both ends have the core respectively, and two core are fixed respectively in the core print cavity, all are equipped with fit clearance between every core and the core print cavity, and every core bottom edge all is equipped with round collection sand groove, and the medial surface of every core or every core lateral surface set up a plurality of abrasive bands arch respectively, and the bellied thickness in every abrasive band all is greater than fit clearance. The utility model discloses a through the abrasive band arch on core print or the core print, make core print and core print form interference fit, unnecessary sand can be fallen by the friction during dress core, falls into the sand collecting tank of core print bottom, and the core location can be assisted to the abrasive band arch, and the process of dress core while rubbing can be well-centered with the core print, size deviation when the dress core among the prior art can be reduced greatly to improve foundry goods size precision effectively, be fit for promoting.

Description

Positioning structure for improving size precision of sand core produced by sand lined iron mold

Technical Field

The utility model belongs to the technical field of the casting of the complicated foundry goods of engine, concretely relates to improve location structure of sand lined metal mould production foundry goods size precision.

Background

The sand core is mainly used for forming an inner cavity and a hole of a casting, the design of the sand core is an important link in the design process of a casting process, and the sand core has direct influence on the quality of the casting, the casting process and the casting process equipment. The cylinder cover belongs to a complex engine part and has high requirements on the wall thickness. When the complex casting is produced, a cylinder cover cavity is formed by the sand core, and if the fit clearance between the sand core and the casting mold is too large, the sand core can move in the casting mold, so that the casting is rejected due to unqualified size and wall thickness.

The core print is an important component of the sand core and refers to the part of the sand core that is not in contact with the metal except for the casting. It includes core head length, inclination, gap and other structure. The core head has the functions of positioning, supporting and fixing the sand core, and can bear the gravity of the sand core and the buoyancy of liquid metal to the core body during pouring. Wherein; the positioning function of the core print is that the core print is matched with the core seat, so that the sand core can be conveniently and accurately placed in the sand mould, the sand core can be divided into a vertical core print and a horizontal core print according to the position of the core print in the sand mould, and the core print of the sand core which is vertically placed during mould closing is the vertical core print.

The compact rate of the molding sand of the tidal film sand is about 80-95, the sand core assembly casting mold can realize zero clearance and form close fit through pressure, the size precision of the casting is higher, and the size precision of the casting can be ensured through the fit of the sand core and the casting mold when the tidal film sand is used for producing a cylinder cover.

Iron mold sand-coated casting is a casting technique for coating a thin layer of molding sand (also called precoated sand) around the inner cavity of a metal mold (also called iron mold). The obtained casting has the advantages of good mechanical property, labor saving, material and equipment saving, low production cost and the like. The compaction rate of the molding sand of the iron mold sand-lined process is all 100, the sand-lined layer is hard and brittle, the core head cannot apply pressure integrally when the sand core is installed, and otherwise the sand layer is easy to collapse. In order to ensure the integrity of the casting mold and the sand core, the matching of the sand core and the casting mold can only be clearance matching, and simultaneously, because the sand box of the iron mold sand-coating process has cold and hot states, the size of the core seat can change, the sand core also has dimensional changes such as deformation, and in order to ensure that the cold and hot states can smoothly load and unload the core, the matching clearance of the core head is larger than that of the damp mold process, so that the forming dimensional precision of the mud core is lower than that of the damp mold.

Because the heating temperature of the mold and the iron mold is different, the casting temperature is different when the core is filled, and the conventional iron mold sand-coating process usually selects to enlarge the fit clearance of the sand core to ensure the integrity of the sand core and the casting mold so as to normally fill the core in both a cold state and a hot state. Therefore, when the core is installed, the gap is large, the position of the sand core is not fixed, the size of the casting is prone to generating deviation and uneven wall thickness, particularly, the casting is developed towards the direction of reducing the wall thickness under light weight and tide, and the risk caused by core installation fluctuation is large. For the casting with complexity and high requirement on wall thickness dimension, such as a cylinder cover, the casting is easy to reject due to unqualified wall thickness.

SUMMERY OF THE UTILITY MODEL

The utility model provides an improve iron mold sand lining production psammitolite size precision's location structure, the concrete scheme is as follows:

the utility model provides an improve location structure of sand core size precision of sand-lined metal mold production, includes psammitolite body and core print, psammitolite body both ends have the core respectively, and two core are fixed respectively in the core print cavity, all are equipped with fit clearance between every core and the core print cavity, and every core bottom edge all is equipped with round sand collecting tank, and the medial surface of every core print or every core lateral surface set up a plurality of abrasive band archs respectively, and the bellied thickness in every abrasive band all is greater than fit clearance.

Furthermore, the abrasive belt bulges are arc cylinders, trapezoidal cylinders, triangular cylinders or semicircular cylinders, and the thickness of each abrasive belt bulge is 0.5-4mm larger than the matching gap.

Further, the sand trap is arranged according to the shape of the core print.

Furthermore, the core print is a circular vertical core print, the sand collecting groove is an annular groove, and at least three abrasive belt bulges are circumferentially arrayed on the inner circumferential surface of each core print or the outer circumferential surface of each core print.

Furthermore, the core print is a square vertical core print, the sand collecting groove is a groove shaped like a Chinese character 'hui', and at least one abrasive belt bulge is respectively arranged on four inner sides of each core print or on four outer sides of each core print.

Furthermore, the core print is a horizontal core print, the overlooking sections of the two core print bases are symmetrical C-shaped, the sand collecting groove is a C-shaped groove, and at least one abrasive belt bulge is arranged on three inner sides of each core print base or the outer side surface of each core print base respectively.

The advantages of the utility model

The utility model provides an improve sand-lined metal mold production foundry goods size precision's location structure, it is protruding through design abrasive band on core print or core print, it can make core print and core print form interference fit under the cold and hot condition of sand box (core print size can change), unnecessary sand can be rubbed off during the dress core, the process of dress core while rubbing can be with core print alignment steady, thereby improve the positioning accuracy of psammitolite, lower core is accomplished back psammitolite body or core print and abrasive band arch is zero clearance, make the undulant greatly reduced of dress core, different staff's operation can not cause the psammitolite body to have the fluctuation in core print position yet. The sand belt protrusion can assist in core installation and positioning, the core head can be centered in the process of installing the core while rubbing, and the size deviation in the prior art can be greatly reduced, so that the size precision of the casting is effectively improved, the casting with complex casting is favorably cast, and the casting with high requirements on wall thickness and size can be effectively scrapped due to the fact that the casting size and the wall thickness are not combined. The problems that the existing sand-lined metal mold process usually increases the gap between the core heads to ensure the integrity of the core heads and the casting molds, but causes larger core setting size deviation, thereby causing the deviation of the casting size and the uneven wall thickness are solved. And the method has a larger fault tolerance rate on the deformation of the casting mold under the cold and hot conditions. Can be widely applied to the core print design of various complicated castings produced by the sand-lined metal mold process.

Drawings

FIG. 1 is a schematic front view of a circular vertical core print and a core print seat after core setting in example 1.

Fig. 2 is a schematic view of a top view of the core print of fig. 1.

FIG. 3 is a schematic view of a plane structure of example 1 after core setting.

FIG. 4 is a schematic top view of a square vertical core print and a core print seat after core setting in example 2.

Fig. 5 is an enlarged view of a portion of the structure of fig. 4.

FIG. 6 is a top view of the horizontal core print and the core print base after core setting in example 3.

Fig. 7 is a schematic view of a main surface portion structure of fig. 6.

Fig. 8 is a schematic view of a top view of the core print of fig. 6.

FIG. 9 is a schematic top view of the core print and core print base of example 4 without abrasive belt after core setting.

Figure 10 is a schematic cross-sectional view of a horizontal core print of example 4 cored-out abrasive belt.

Fig. 11 is a schematic view of a core print with a trapezoidal column as the sanding belt protrusion 4 in embodiment 1.

Fig. 12 is a schematic view of a core print with a triangular column-shaped protrusion 4 of the abrasive belt of embodiment 1.

In the figure:

1. a core print; 2. a core print; 3. fitting gaps; 4. the abrasive belt is raised; 5. a sand collecting tank; 6. the sand core body.

Detailed Description

The present invention will be further explained with reference to the drawings and the embodiments, and it should be noted that the embodiments are not intended to limit the scope of the present invention.

Example 1

As shown in fig. 1 and 3, the positioning structure for improving the dimensional accuracy of a sand core produced by sand-lined metal mold according to embodiment 1 includes a sand core body and a core base 1, core heads 2 are respectively disposed at two ends of the sand core body, the core heads 2 are circular vertical core heads, the two core heads 2 are respectively fixed in cavities of the core base 1, a fit gap 3 is disposed between each core head 2 and the cavity of the core base 1, three abrasive belt protrusions 4 are arrayed along at least a circumference of an inner circumferential surface of each core base 1 or an outer circumferential surface of each core head 2, the abrasive belt protrusions 4 are arc cylinders, trapezoidal cylinders, triangular cylinders, or semicircular cylinders, and a thickness of each abrasive belt protrusion 4 is 0.5-4mm greater than the fit gap. Preferably, the thickness of abrasive belt protrusion 4 of embodiment 1 is the radius of a semicircular cylinder. Every 1 bottom edge of core print all is equipped with round sand collection groove 5, and sand collection groove 5 is the annular groove, and sand collection groove 5 can set up according to the shape of core print 2.

The thickness of the abrasive belt bulge 4 is 0.5-4mm larger than the fit clearance, and the abrasive belt bulge 4 is designed into an arc cylinder, a trapezoid cylinder or a triangular cylinder or a semicircular cylinder, so that one end of the abrasive belt bulge 4 close to the core print 2 is gradually thickened and transited towards the direction of the core base 1, the abrasive belt bulge 4 is not easily wiped off by a lower core, the auxiliary positioning effect on the core print 2 can be realized, the abrasive belt bulge 4 can be easily rubbed off by the core print 2 in the core mounting process, the core mounting difficulty is avoided, and the core mounting error caused by the large fit clearance 3 can be well solved while the workload of workers is not increased.

As the abrasive belt protrusion 4 is additionally arranged to assist in centering of the core print, on the basis of the design, the fit clearance 3 in the cavity of the core print 2 and the core base 1 can be further enlarged, when the machine modeling, the wet modeling and the production quantity in the prior art are large, the common fit clearance 3 is 0.5-lmm, and the common clearance 3 is 1.5-3mm in the conventional iron mold sand-coating process, under the condition of the design, the longer fit clearance can be widened to 4-5mm, and the larger fault tolerance rate is realized for the deformation of a casting mold under the cold and hot conditions.

The working principle is as follows: at the dress core in-process, put into the sand box that has modelled with psammitolite body 6, put into core print 1 cavity after core print 2 is put through abrasive band arch 4 and is made a heart, when core print 2 got into core print 1, be greater than the coincidence of partial abrasive band arch 4 and core print 2 of fit clearance 3 behind the lower core and fallen into sand collecting tank 5 by the friction, core print 2 reaches zero clearance with core print 1 and closely cooperates, prevents that core print 2 from rocking, blows off the loose sand that is fallen by the friction after the dress core is accomplished.

Example 2

As shown in fig. 4 and 5, the positioning structure for improving the size precision of the sand core for sand-lined metal mold production provided by this embodiment 2 includes a sand core body and a core base 1, core heads 2 are respectively disposed at two ends of the sand core body, the core heads 2 are square vertical core heads, the two core heads 2 are respectively fixed in cavities of the core base 1, a fit gap 3 is respectively disposed between each core head 2 and the cavity of the core base 1, and at least one abrasive belt protrusion 4 is respectively disposed on four inner sides of each core base 1 or four outer sides of each core head 2. The abrasive belt bulges 4 are semi-circular cylinders, a circle of sand collecting groove 5 is arranged at the edge of the bottom of each core print 1, the sand collecting grooves 5 are grooves shaped like Chinese character 'hui', and the thickness of each abrasive belt bulge 4 is 0.5-4mm larger than the fit clearance. The thickness of the abrasive belt bulge 4 is the radius of a semicircular cylinder. The working principle is the same as in embodiment 1.

Example 3

As shown in fig. 6 to 8, the positioning structure for improving the size precision of the sand core in sand lined metal mold production provided by this embodiment 3 includes a sand core body and a core holder 1, core heads 2 are respectively provided at two ends of the sand core body 6, the core heads 2 are square horizontal core heads, the overlooking cross sections of two core holders 1 are symmetrical C-shaped, the two core heads 2 are respectively fixed in cavities of the core holder 1, a fit clearance 3 is provided between each core head 2 and the cavity of the core holder 1, and at least one abrasive belt protrusion 4 is provided on three outer side surfaces of each core head 2 corresponding to the cavity of the core holder 1. The abrasive belt bulges 4 are semicircular cylinders, the edge of the bottom of each core print 1 is provided with a circle of sand collecting groove 5, each sand collecting groove 5 is a C-shaped groove, and the thickness of each abrasive belt bulge 4 is 0.5-4mm larger than the fit clearance. The thickness of the abrasive belt bulge 4 is the radius of a semicircular cylinder. The working principle is the same as in embodiment 1.

Comparative example 4

As shown in fig. 9 and 10, neither the square vertical core print of fig. 9 nor the horizontal core print of fig. 10 has a sanding belt on the core print holder 1 or the core print 2. Four faces of the square vertical core print or three faces of the horizontal core print are provided with matching gaps 3, when in operation, the core prints can move up and down and left and right in the range of the matching gaps 3, the cores can not be at the same fixed position every time, and the core loading position can not be fixed. The general fit clearance of the sand lined metal mold process is 1.5-3mm, which means that the maximum variation of the sand core position in the vertical and horizontal directions after manual core setting can reach 3-6mm, so that the maximum wall thickness difference of a casting formed by the sand core can reach 3-6mm, and the quality hidden danger is very large.

And adopt utility model's location structure, psammitolite body 6 removes to be 0 in 1 position of core print for the foundry goods wall thickness stability greatly increased that psammitolite body 6 formed has important meaning to reducing wall thickness, stable control wall thickness under the lightweight tide.

Application example 1

The CL200 cylinder cover exhaust passage core produced by my department is used for processing and positioning, one end of the sand core body is a circular vertical core print which is vertically arranged on a chassis core seat (hot core), and the other end of the sand core body is a square horizontal core print which is horizontally arranged on a central chassis core seat (hot core). The fit clearance between the core print and the chassis core print designed according to the comparative example 4 is 2mm, and the movement during pouring is prevented by adopting viscose fixation. Due to the fact that fit clearance exists, positions of the air channel cores are different after the cores are installed at each time, and the lower cores of the air channel cores are unstable, so that positioning points are fluctuated, the wall thickness of the air channel is unstable, the machining size is unstable, the rate that the front end face of a CL200 cylinder cover cannot be scrapped during machining is up to 3.5%, the rate of scrapping of unqualified wall thicknesses of the air channel is 2.6%, and the standard deviation of the wall thickness of the air channel is 1.34.

One end of the circular vertical core print is improved by adopting the scheme of the embodiment 1, as shown in figure 3, the fit clearance between the circular vertical core print and the chassis core print is 2mm, and three equidistant semicircular abrasive belt bulges with the radius of 3m are arrayed along the circumference of the outer circumference edge of the chassis core print. The circular vertical core print of the cylinder cover and the chassis core seat 1 are both circular, the sand core body is placed in the molded sand box, the circular vertical core print is placed in alignment with the chassis core seat, and the circular vertical core print is in a regular round rod shape. When the circular vertical core print is put into the chassis core print, the part of the three sand belt bulges of the core print is rubbed off, sand falls into the sand collecting groove, and the circular vertical core print is tightly matched with the chassis core print in a zero clearance manner to prevent the core print from shaking.

One end of the square horizontal core print is improved by adopting the scheme of the embodiment 3, as shown in fig. 10, three abrasive belt bulges are arranged on three side positions of the square horizontal core print, and the distance between the square horizontal core print and the central disk core seat is 2mm. The abrasive belt bulge on the square horizontal core print is a semicircular cylinder with the radius of 3 mm. When the core is placed, the square horizontal core print is contacted with the central core print seat, the redundant part of the square horizontal core print is rubbed off and is tightly matched with the central core print seat in a zero clearance way, and redundant sand needs to be blown clean by an air pipe.

After the improvement of the schemes of the embodiment 1 and the embodiment 3, the rejection rate of the CL200 cylinder cover exhaust passage core which cannot be machined and has improper wall thickness of the air passage is 0, the standard deviation of the wall thickness of the air passage is 0.23, the reduction is 82.8%, and the effect is obvious.

Claims (6)

1. The utility model provides an improve location structure of sand core size precision of sand lined metal mould production which characterized in that, includes psammitolite body and core print, psammitolite body both ends have the core respectively, and two core are fixed respectively in the core print cavity, all are equipped with fit clearance between every core and the core print cavity, and every core bottom edge all is equipped with round sand collecting tank, and the medial surface of every core or every core lateral surface of every core set up a plurality of abrasive band archs respectively, and the bellied thickness in every abrasive band all is greater than fit clearance.

2. The positioning structure of claim 1, wherein the belt protrusions are circular cylinders, trapezoidal cylinders, triangular cylinders or semicircular cylinders, and the thickness of each belt protrusion is 0.5-4mm larger than the fit clearance.

3. The positioning structure according to claim 1, wherein the sand trap is provided according to the shape of the core print.

4. The positioning structure according to claim 1, wherein the core print is a circular vertical core print, the sand trap is an annular groove, and at least three belt protrusions are circumferentially arrayed on the inner circumferential surface of each core holder or the outer circumferential surface of each core print.

5. The positioning structure according to claim 1, wherein the core print is a square vertical core print, the sand trap is a zigzag groove, and at least one belt protrusion is provided on four inner sides of each core print or four outer sides of each core print.

6. The positioning structure of claim 1, wherein the core print is a horizontal core print, the two core prints are symmetrical C-shaped in cross section in plan view, the sand collecting groove is a C-shaped groove, and at least one belt protrusion is respectively disposed on three inner sides of each core print or on the outer side of each core print.

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