CN110605359B

CN110605359B - Low-cost titanium alloy machining graphite mold casting method

Info

Publication number: CN110605359B
Application number: CN201910939931.0A
Authority: CN
Inventors: 石明星; 焦海峰; 刘英智; 郑栓柱; 李勇
Original assignee: Beijing Xinghang Electromechanical Equipment Co Ltd
Current assignee: Beijing Xinghang Electromechanical Equipment Co Ltd
Priority date: 2019-09-30
Filing date: 2019-09-30
Publication date: 2021-01-08
Anticipated expiration: 2039-09-30
Also published as: CN110605359A

Abstract

The invention provides a low-cost titanium alloy machining graphite mold casting method which comprises the steps of pouring system design, graphite mold design, smelting pouring, disassembly and recovery. The cost of the graphite casting mold is reduced by 20-30%, and the graphite casting mold has high popularization value; the recovery of partial casting mold is realized by optimizing the casting system, designing the graphite mold and accurately controlling the amount of cast metal, and the recovery rate is over 50 percent; the invention adopts external mold layered design, small contact design and staggered die drawing for the first time to realize the reuse of the graphite type of the multi-chuck frame casting; the pouring system, the graphite type structure and the fixing mode are convenient to disassemble and clean, the graphite blocks are not easy to damage, and the graphite type is favorably recycled.

Description

Low-cost titanium alloy machining graphite mold casting method

Technical Field

The invention belongs to the technical field of titanium alloy casting, and particularly relates to a low-cost titanium alloy machining graphite mold casting method.

Background

At present, the most widely applied technological methods for titanium alloy casting are investment casting technology and machining graphite type technology, investment casting is suitable for casting complex thin-wall castings, but for some large-size weak-rigidity titanium alloy castings, investment casting cannot guarantee the size precision and metallurgical quality of the castings, only the machining graphite type casting technology can be adopted, and the technological method has the advantages of flexible design, unlimited casting parting surface, short processing period, high size stability and the like, and is a common choice for titanium alloy casting manufacturers at home and abroad. But machine adds graphite casting titanium alloy cost is higher, on the one hand, graphite raw material cost constantly increases, machine adds a kilogram graphite casting mould and exceeds fifty yuan, on the other hand, the back is accomplished in the graphite casting mould pouring, can only use once, lead to machine to add graphite type foundry goods cost higher, especially some large-scale complicated titanium alloy castings, the graphite quantity reaches several tons even, titanium liquid pours into the graphite type and solidifies the in-process that becomes the foundry goods and can stronger contractility, casting structure, fixed position instrument, gating system etc. can produce powerful hindrance effect to graphite type recovery, lead to can not play the mould, secondly during the graphite type pouring, receive titanium liquid high temperature effect and fill the pressure of type pressure head, produce the crackle easily, can not be used for next use, and the metal volume of pouring is difficult to control, the metal liquid that spills over and splashes causes very big difficulty for retrieving.

Disclosure of Invention

Technical problem to be solved

The invention provides a low-cost titanium alloy machining graphite mold casting method, which aims to solve the technical problem of reducing the casting cost.

(II) technical scheme

In order to solve the technical problem, the invention provides a low-cost titanium alloy machining graphite type casting method, which comprises the following steps:

s1, designing a pouring system:

the pouring position is selected on the central plane of the casting, the ingates are concentrated on the central plane, and the length of the ingates is prolonged to ensure that the distance between the horizontal pouring channel and the outer surface of the casting mold is 30-50 mm;

s2, graphite type design:

s2-1, selecting a casting mold parting surface on a casting center plane, dividing a graphite outer mold to be recovered into a plurality of blocks, controlling a single block of graphite to be 40-90 kg, controlling the local minimum wall thickness to be not less than 5mm, and simultaneously drilling 2-8 hoisting holes on two end surfaces; for the revolving body casting, the recovery graphite stripping positions are in staggered fit or are provided with 3-5-degree draft angles. For a frame casting with a clamp, the recovered graphite is designed in a layered mode, namely an upper outer die and a lower outer die are designed into four layers from two layers, the inner layer forms a cavity of the casting, the wall thickness of the cavity is controlled to be 10-15 mm, the outer layer is used for recovery, the minimum wall thickness is controlled to be 30-50 mm, the inner layer and the outer layer are provided with 3-5-degree draft angles, the clamp is independently designed to be tightly matched with the inner layer, the clamp is in non-contact fit with the outer layer, a 2-4 mm gap is reserved, and meanwhile, the clamp is limited at the outermost side of the outer layer, so that fire escape in;

s2-2, fixing the recovered graphite by bolts and nuts, wherein the interval between the two fixing positions is 300-600 mm, and the bolts are in clearance fit with the graphite and are convenient to detach. The recovered graphite and the core are positioned by 1-3 pins, and the diameter of each pin is 10-12 mm;

s3, smelting, pouring, disassembling and recycling:

the amount of the poured metal is controlled through a smelting process, so that the phenomenon that the amount of the poured metal is increased and overflows to block the recovery of graphite is prevented;

after the graphite mold is poured, cooling to below 100 ℃ and cleaning, firstly, destroying the graphite on the ingate, then cutting off the ingate by acetylene flame to separate the casting mold from the pouring channel, and for a pouring cup on the sprue, after a bolt nut is disassembled, the recovery can be realized along the mold opening direction; for the recovery of the graphite outer mold, firstly, the casting mold is placed on a flat floor, the bolt is knocked out after the nut is disassembled, the hoisting rod is placed at the hoisting hole, force is stably applied by a crown block along the mold opening direction, the positioning position of the pin is manually knocked to stably apply force, the pin is smoothly pulled out, and the graphite is disassembled block by block from top to bottom; the recovered graphite is blown clean on the surface by an air pipe, the surface characteristics of the graphite are complete, the graphite can be repeatedly used, and if the graphite is locally damaged, a loose piece is independently processed to replace the damaged part.

Further, in step S1, the graphite type pouring cup is of an outer square and inner circle structure, a pouring cup base is added, a dismounting hole is arranged on the outer mold of the pouring cup in a matched mode, the pouring cup is fixed through a bolt and a nut, the bolt is in clearance fit with the graphite, and the pouring cup is convenient to dismount.

Further, in step S3, the melting weight is calculated from the sum of the casting weight, the skull weight, and the funnel weight, and then the melting stroke is calculated by substituting the ingot diameter, the crucible diameter, and the alloy density constant, thereby precisely controlling the amount of metal.

Further, in step S3, the mold is covered with asbestos cloth before casting to prevent the casting splash from overflowing from the hopper.

(III) advantageous effects

The invention provides a low-cost titanium alloy machining graphite mold casting method which comprises the steps of pouring system design, graphite mold design, smelting pouring, disassembly and recovery.

Compared with the prior art, the invention has the beneficial effects that:

1. the cost of the graphite casting mold is reduced by 20-30%, and the graphite casting mold has high popularization value.

2. The invention realizes the recovery of partial casting mould by optimizing the casting system, designing the graphite mould and accurately controlling the amount of cast metal, and the recovery rate is over 50 percent.

3. The invention adopts external mold layering design, small contact design and staggered die drawing for the first time to realize the reuse of the graphite type of the multi-chuck frame casting.

4. The pouring system, the graphite type structure and the fixing mode are convenient to disassemble and clean, the graphite blocks are not easy to damage, and the graphite type is favorably recycled.

Drawings

FIG. 1 is a design drawing of the recovery of a topping cup in an embodiment of the present invention: (a) an outer structure; (b) an internal structure;

FIG. 2 is a design drawing of a ring mold according to example 1 of the present invention;

FIG. 3 is a design drawing of a frame mold according to example 2 of the present invention.

Detailed Description

In order to make the objects, contents and advantages of the present invention clearer, the following detailed description of the embodiments of the present invention will be made in conjunction with the accompanying drawings and examples.

Example 1

The technical scheme of the invention is further explained by taking an annular ring casting as an example, and the maximum outline dimension of the casting is phi 613 multiplied by 786 mm.

S1, designing a pouring system:

the pouring position is selected on the circle center plane of the casting, the four ingates are concentrated on the circle center plane, and the length of the ingates is prolonged to ensure that the cross gate is 40mm away from the outer surface of the casting mold. As shown in figure 1, the graphite type pouring cup is designed into an outer square and inner circle structure, the two parts are designed into three parts, a pouring cup base is added, meanwhile, a dismounting hole is matched on an outer die of the pouring cup, fixing of the pouring cup is changed from iron wire fixing into bolt and nut fixing, and a bolt is in clearance fit with graphite and is convenient to dismount, as shown in figure 2.

S2, graphite type design:

s2-1, selecting a casting mold parting surface on a casting center plane, controlling a single graphite block to be 50-70 kg, controlling the local minimum wall thickness to be 32mm, drilling 4 hoisting holes on two end surfaces, and matching the recovered graphite mold stripping positions in a staggered manner.

S2-2, fixing the recovered graphite by four groups of bolts and nuts, wherein the interval between the two fixing positions is 450mm, and the bolts are in clearance fit with the graphite and are convenient to disassemble. The recovered graphite and the core are positioned by 2 pins, and the diameter of each pin is 12 mm.

S3, smelting, pouring, disassembling and recycling:

the metal content of the casting is 154 kg, the weight of the skull is 27 kg, the weight of the funnel is 16 kg, the diameter of the ingot is 285mm, the diameter of the crucible is 450mm, and the alloy density is 4.5g/cm³And the calculated smelting stroke is 385mm, after the pouring is finished, the metal amount accounts for 3/4 of the pouring cup, no overflow is found, and because the pouring of the casting mold is covered by asbestos cloth, the splashing in the funnel is effectively isolated.

After the graphite mold is poured, cooling to below 100 ℃ and cleaning, firstly, destroying the graphite on the ingate, then cutting off the ingate by acetylene flame to separate the casting mold from the pouring channel, and for a pouring cup on the sprue, after a bolt nut is disassembled, the recovery can be realized along the mold opening direction; for the recovery of the graphite outer mold, firstly, the casting mold is placed on a flat floor, the bolt is slightly knocked out by a mallet after the nut is disassembled, a hoisting rod is placed in a hoisting hole, force is stably applied by a crown block along the mold opening direction, the positioning position of the pin needs to be manually knocked to stably apply force, the pin is smoothly pulled out, and the graphite is disassembled from top to bottom one by one. Totally four pieces of graphite are recovered, the surface characteristics are complete, the graphite can be used for the next furnace, as shown in fig. 3, the recovery rate of the graphite exceeds 55%, the cost of the second furnace is saved by about 2.5 ten thousand yuan, and the recovered graphite is broken in the process of disassembly after being reused, so that the cost of the graphite is reduced by about 30% compared with the scheme that the graphite is not recovered.

Example 2

The technical scheme of the invention is further explained by taking a frame casting with a clamp as an example, the maximum outline dimension of the casting is 1438 multiplied by 475 multiplied by 47mm, the casting is provided with 10 clamps, the graphite mold is composed of 23 cores, the deformability of the graphite is poor, the cores and the casting, the clamps and the casting mold generate strong interaction, and the recycling difficulty of the external mold is very large.

S1, designing a pouring system:

the pouring position is selected on the central plane of the casting, four ingates are concentrated on the central plane, and the length of the ingates is prolonged to ensure that the cross runners are 30mm away from the outer surface of the casting. The graphite type pouring cup is designed into a square outside and round inside structure, the two parts are designed into three parts, a pouring cup base is added, meanwhile, a dismounting hole is matched on the outer die of the pouring cup, the pouring cup is fixed by an iron wire and is fixed by a bolt and a nut, and the bolt is in clearance fit with the graphite and is convenient to dismount. Two pieces are poured in each furnace, and a bilateral symmetry pouring combination mode is adopted, as shown in figure 3.

S2, graphite type design:

s2-1, selecting a casting mold parting surface on a casting center plane, dividing a graphite outer mold to be recovered into a plurality of blocks, controlling a single block of graphite to be 70 kg, controlling the local minimum wall thickness to be 18mm, simultaneously drilling 3 hoisting holes on two end surfaces, wherein the recovered graphite is in a layered design, namely, an upper outer mold and a lower outer mold are designed into four layers from two layers, an inner layer forms a cavity of the casting, the wall thickness of the cavity is controlled to be 15mm, an outer layer can be used for recovery, the minimum wall thickness is controlled to be 43mm, the inner layer and the outer layer are provided with 5-degree draft angles, a graphite mold is independently designed at a chuck and is tightly matched with the inner layer, the graphite mold is in non-contact fit with the outer layer, a 3mm gap is reserved, and the chuck is.

S2-2, two fixing bolt nuts are arranged on graphite on two sides of the chuck, 20 groups of bolt nuts are used for fixing, the two fixing positions are spaced by 200-400 mm, and the bolts are in clearance fit with the graphite and are convenient to detach. The recovered graphite and the core are positioned by 7 pins, and the diameter of each pin is 10 mm.

S3, smelting, pouring, disassembling and recycling:

the metal content of the casting is 130 kg, the weight of the solidified shell is 22 kg, the weight of the funnel is 15 kg, the diameter of the cast ingot is 280mm, the diameter of the crucible is 450mm, and the alloy density is 4.5g/cm³And the calculated smelting stroke is 310mm, after the pouring is finished, the metal amount accounts for 1/2 of the pouring cup, no overflow is found, and because the pouring of the casting mold is covered by asbestos cloth, the splashing in the funnel is effectively isolated.

After the graphite mold is poured, cooling to below 100 ℃ and cleaning, firstly, destroying the graphite on the ingate, then cutting off the ingate by acetylene flame to separate the casting mold from the pouring channel, and for a pouring cup on the sprue, after a bolt nut is disassembled, the recovery can be realized along the mold opening direction; for the recovery of the graphite outer mold, firstly, the casting mold is placed on a flat floor, the bolt is slightly knocked out by a mallet after the nut is disassembled, a hoisting rod is placed in a hoisting hole, force is stably applied by a crown block along the mold opening direction, the positioning position of the pin needs to be manually knocked to stably apply force, the pin is smoothly pulled out, and the graphite is disassembled from top to bottom one by one. The method has the advantages that four graphite blocks are recycled, the surface characteristics are complete, the method can be used for the next furnace, the graphite recovery rate exceeds 50%, after the recycled graphite is reused for one time, the surface characteristics are complete after the recycled graphite is disassembled and can still be used continuously, the cost of the second furnace is saved by about 1.9 ten thousand yuan, the recycled graphite is broken after the second furnace is poured and cleaned, the use is not influenced, the cost of the third furnace is saved by about 1.9 ten thousand yuan, the graphite is seriously damaged after the third furnace is poured and cannot be used continuously, so that the outer mold can be reused for two times, and compared with a graphite non-recovery scheme, the graphite cost is reduced by about 20%.

The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.

Claims

1. A low-cost titanium alloy machining graphite type casting method is characterized by comprising the following steps:

s1, designing a pouring system:

s2, graphite type design:

s2-1, selecting a casting mold parting surface on a central plane of the casting, dividing a graphite outer mold to be recovered into a plurality of blocks, controlling the single graphite block to be 40-90 kg, controlling the local minimum wall thickness to be not less than 5mm, and simultaneously drilling 2-8 hoisting holes on two end surfaces; the recycled graphite is in a layered design, namely an upper external mold and a lower external mold are designed into four layers from two layers, the inner layer forms a cavity of a casting, the wall thickness of the cavity is controlled to be 10-15 mm, the outer layer is used for recycling, the minimum wall thickness is controlled to be 30-50 mm, the inner layer and the outer layer are provided with 3-5 degrees of draft angle, a graphite mold is independently designed at a chuck and is tightly matched with the inner layer, the graphite mold is in non-contact fit with the outer layer, a 2-4 mm gap is reserved, and meanwhile, the chuck is limited at the outermost side of the outer layer, so that;

s2-2, fixing the recovered graphite by bolts and nuts, wherein the two fixing positions are separated by 300-600 mm, and the bolts are in clearance fit with the graphite and are convenient to disassemble; the recovered graphite and the core are positioned by 1-3 pins, and the diameter of each pin is 10-12 mm;

s3, smelting, pouring, disassembling and recycling:

after the graphite mold is poured, cooling to below 100 ℃ and cleaning, firstly, destroying the graphite on the inner pouring gate, then cutting off the inner pouring gate by acetylene flame to separate the casting mold from the pouring gate, and after the bolt nut is disassembled for the pouring cup on the straight pouring gate, the pouring cup can be recovered along the die opening direction of the pouring cup; for the recovery of the graphite outer mold, firstly, the casting mold is placed on a flat floor, the bolt is knocked out after the nut is disassembled, the hoisting rod is placed at the hoisting hole, force is stably applied by a crown block along the mold opening direction, the positioning position of the pin is manually knocked to stably apply force, the pin is smoothly pulled out, and the graphite is disassembled block by block from top to bottom; the recovered graphite is blown clean on the surface by an air pipe, the surface characteristics of the graphite are complete, the graphite can be repeatedly used, and if the graphite is locally damaged, a loose piece is independently processed to replace the damaged part.

2. The casting method as claimed in claim 1, wherein in step S1, the graphite type pouring cup is of an outer square and inner round structure, a base of the pouring cup is added, a dismounting hole is formed in an outer die of the pouring cup, the pouring cup is fixed by a bolt and a nut, and the bolt is in clearance fit with the graphite for convenient dismounting.

3. The casting method as recited in claim 1, wherein in the step S3, a melting weight is calculated from a sum of the casting weight, the skull weight and the funnel weight, and then substituted into the ingot diameter, the crucible diameter, the alloy density constant to calculate a melting stroke, thereby precisely controlling the amount of metal.

4. The casting method as described in claim 1, wherein in said step S3, the mold is covered with asbestos cloth before casting to prevent casting splash from overflowing from the hopper.