WO2018039852A1

WO2018039852A1 - Casting method for monolithic multi-way valve body casting

Info

Publication number: WO2018039852A1
Application number: PCT/CN2016/097127
Authority: WO
Inventors: 丁先华
Original assignee: 丁先华
Priority date: 2016-08-29
Filing date: 2016-08-29
Publication date: 2018-03-08

Abstract

Disclosed is a casting method for a monolithic multi-way valve body casting, the method comprising the steps of: preparing a core producing mould, and checking and cleaning the mould; producing a main core by mould sand, and demoulding by spraying a mould release agent after the main core is shaped; preparing small cores, and drilling exhaust holes in the small cores; removing flash on the main core and the small cores, and removing a transition nozzle on the main core; fixing the main core by a sand core bonding preparation tooling, firstly assembling the small core at one side, and then assembling the small core at the other side; mounting the assembled sand core into a shell body; and casting a valve body: performing a pouring process via a side thin gate on two sides at the same time, using an exothermic riser 120 mm in diameter and 220 mm in height, and placing a dedicated chill iron at the bottom face of the shell body. The monolithic multi-way valve body casting produced by such a casting method has the advantages of the linearity of a main valve hole of the casting blank being controlled to be less than or equal to 1.0 mm, ensuring the valve hole linearity, solving the problems of shrinkage cavity, shrinkage porosity, internal gas holes and other casting defects of the casting, especially defects of micropores of the casting, and improving the compactness of the internal structure.

Description

Method for casting integral multi-way valve body casting

Technical field

The invention relates to the technical field of engineering machinery equipment manufacturing, in particular to a method for casting a whole multi-way valve body casting.

Background technique

The product manufactured by the manufacturing method is a key component of the hydraulic control system of the large excavator, and is the development direction of the hydraulic control system of the large excavator today.

An excavator, also known as a digging machine, is a earthmoving machine that uses a bucket to excavate materials above or below the surface of the carrier and into the transport vehicle or to the stockyard. From the development of construction machinery in recent years, the development of excavators is relatively fast, and excavators have become one of the most important construction machinery in engineering construction.

Most of today's large excavators have hydraulic control systems. The hydraulic system consists of hydraulic pumps, control valves, hydraulic cylinders, hydraulic motors, pipelines, fuel tanks, etc. The hydraulic transmission system transmits the power of the engine to the hydraulic pressure through hydraulic pumps. Actuators such as motors and hydraulic cylinders act to drive the work unit to complete various operations.

The hydraulic valve is a key component of the hydraulic system. The hydraulic valve structure and precision requirements of the large excavator are very high, especially for some multi-oil valves. The temperature rises rapidly during the working process, and the temperature is too high, resulting in the hydraulic valve not working stably. And the amount of wear is large, the pressure fluctuation or shock vibration of the hydraulic system will cause the valve body to leak, and the pressure is ≥35Mpa, the pressure is more likely to leak under the high pressure working condition, the hydraulic valve body casting shrinkage, shrinkage, internal air hole casting, etc. The problem is often a defect in the product, requiring a higher internal tissue compactness and a straightness of the main valve hole casting blank of less than 1.0 mm.

Summary of the invention

The object of the present invention is to provide an integral multi-way valve for the defects existing in the prior art. Casting method of valve body casting, casting valve body casting control main valve hole casting blank straightness is less than or equal to 1.0 mm, ensuring valve hole straightness, solving cast casting shrinkage, shrinkage, internal air hole and other casting defects, especially casting internal micropores The defect is to improve the internal organization compactness to achieve no leakage under the high pressure working condition with rated pressure ≥35Mpa.

In order to solve the above technical problems, the present invention provides a method for casting an integral multi-way valve body casting, comprising the following steps:

S1, preparing a core mold, inspecting the mold and cleaning the dirt on the mold;

S2: The main core is made of sand, and the steel bar is placed in the main hole of the main core as a core bone, and the vent needle is placed in the mold in sequence, and the vent needle is rotated one turn after the sand is finished, after the main core is shaped, Demolding with a spray release agent;

S3, preparing a small core, drilling a vent hole at a position of a vertical rib on the small core;

S4, repairing the main core, the small core on the blunt, removing the transition nozzle on the main core;

S5. Fix the main core through the sand core bonding tool, first assemble the small core of one side to the main core, and after the adhesive is completely solidified, turn over the assembled sand core and fix the main core through the sand core bonding tool. And then assemble the small core on the other side to the main core;

S6, preparing a casing, and installing the assembled sand core into the casing;

S7, valve body casting: using the side thin gate on both sides of the simultaneous casting process, the use of 120mm diameter, 220mm high riser riser, placed special cold iron on the bottom of the shell;

S8. After the valve body is formed, the main core and the small core in the valve body are broken due to high temperature, thereby forming a flow passage of the valve body cavity.

Specifically, the pouring temperature in S7 ranges from 1390 ° C to 1430 ° C, the pouring time ranges from 18 s to 25 s, and the tapping temperature ranges from 1510 ° C to 1530 ° C.

Further, after the pouring is completed, stirring is carried out in the riser to prevent the formation of a small molten pool which cannot be complemented, and the feeding effect is achieved.

Specifically, an asbestos cloth having a shrinkage gap of 1.5 mm is placed at the core of all the main holes, and when the casting is expanded, there will be a gap of 1.5 mm to prevent the bending of the main hole, and in combination with the action of the special cold iron, The straightness of the main hole is within 1.0 mm.

Specifically, S2 further includes using a water-based paint, and adding graphite powder to the water-based paint to prepare a paint having a Baume degree range of 35° Bé-42° Bé.

The heating temperature of the main core in S2 is 150°C-170°C, the sanding pressure is not less than 0.6MPa, the sanding time is not less than 6s, and the curing time is not less than 120s.

The overall multi-way valve body casting manufactured by the manufacturing method of the present invention has the following beneficial effects:

1. Using high-strength HAGD290 type sand core, using HA377 water-based paint, placing 6.5-diameter steel bar as the core in the main hole to increase the bending strength of the main hole and solve the problem of sand core fracture;

2. Due to the intensive and complicated flow path of the casting, the heat is dense and easy to produce defects such as sticky sand. The HA377 water-based paint is used and a certain amount of graphite powder is added as the coating. The Baume degree of the coating is controlled at 35°Bé-42°Bé. Effective control of sand stick defects;

3. Use a hot riser with a diameter of 120mm and a height of 220. The special cold iron is placed on the bottom surface, and the casting process is carried out on both sides of the thin gate. The overheating phenomenon of the riser is directly avoided, and a good heat dissipation effect can be achieved.

4. After the pouring is completed, use mechanical stirring to keep stirring in the riser to prevent the formation of a small molten pool that cannot be filled up, and achieve the feeding effect;

5. In order to ensure that the straightness of the casting is less than 1.0mm, an asbestos cloth with a shrinkage gap of 1.5mm is placed at the core of all the main holes. When the casting expands, there will be a gap of 1.5 to prevent the main hole from being bent. The role of iron, thus ensuring the straightness of the main hole is within 1.0mm.

detailed description

The technical solutions in the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

Example:

The invention provides a method for casting an integral multi-way valve body casting, comprising the following steps:

S2: The main core is made of high-strength HAGD290 type sand. During the production, the steel bar is placed in the main hole of the main core as the core bone, and the ventilation needle is placed in the mold in order, and the vent needle is rotated once after the sand is completed. After the main core is shaped, the release agent is used for demolding;

S6, preparing a casing, and installing the assembled sand core into the casing;

S7, valve body casting: using the side thin gate on both sides of the simultaneous casting process, using a 120mm diameter, 220mm high riser, placing special cold iron on the bottom of the shell, changing the solidification sequence of molten iron, increasing the solidification speed of the bottom molten iron;

Specifically, the pouring temperature range of the valve body pouring is 1390 ° C - 1430 ° C, the pouring time range is 18 s -25 s, and the tapping temperature range is 1510 ° C - 1530 ° C.

Specifically, the preparation of the main core further includes using a HA377 water-based paint, and adding graphite powder to the water-based paint to prepare a paint having a Baume degree range of 35° Bé-42° Bé.

Specifically, the heating temperature in the main core is 150° C.-170° C., the sanding pressure is not less than 0.6 MPa, the sanding time is not less than 6 s, and the curing time is not less than 120 s.

The above is only the preferred embodiments of the present invention, and the scope of the present invention is not limited thereto, and thus equivalent changes made in the claims of the present invention are still within the scope of the present invention.

Claims

The invention relates to a method for casting a multi-way valve body casting, which comprises the following steps:

S1, preparing a core mold, inspecting the mold and cleaning the dirt on the mold;

S2: The main core is made of sand, and the steel bar is placed in the main hole of the main core as a core bone, and the vent needle is placed in the mold in sequence, and the vent needle is rotated one turn after the sand is finished, after the main core is shaped, Demolding with a spray release agent;

S3, preparing a small core, drilling a vent hole at a position of a vertical rib on the small core;

S4, repairing the main core, the small core on the blunt, removing the transition nozzle on the main core;

S5. Fix the main core through the sand core bonding tool, first assemble the small core of one side to the main core, and after the adhesive is completely solidified, turn over the assembled sand core and fix the main core through the sand core bonding tool. And then assemble the small core on the other side to the main core;

S6, preparing a casing, and installing the assembled sand core into the casing;

S7, valve body casting: using the side thin gate on both sides of the simultaneous casting process, the use of 120mm diameter, 220mm high riser riser, placed special cold iron on the bottom of the shell;

S8. After the valve body is formed, the main core and the small core in the valve body are broken due to high temperature, thereby forming a flow passage of the valve body cavity.
The method for casting a valve body casting of an integral multi-way valve according to claim 1, wherein the pouring temperature in the S7 ranges from 1390 ° C to 1430 ° C, the pouring time ranges from 18 s to 25 s, and the tapping temperature ranges from 1510 ° C. 1530 ° C.
The method for casting a valve body casting of an integral multi-way valve according to claim 2, characterized in that after the pouring is completed, stirring is carried out in the riser to prevent the formation of a small molten pool which cannot be complemented, and the feeding effect is achieved.
A method for casting a valve body casting of an integral multi-way valve according to claim 2, characterized in that asbestos having a shrinkage gap of 1.5 mm is placed at the core of all the main holes The cloth, when the casting expands, will have a gap of 1.5 mm to prevent the bending of the main hole, and in combination with the action of the special cold iron, the straightness of the main hole is within 1.0 mm.
The method for casting a valve body casting of an integral multi-way valve according to claim 1, wherein the S2 further comprises using a water-based paint, and adding graphite powder to the water-based paint to prepare a Baume degree range. It is a coating of 35° Bé-42° Bé.
The method for casting a valve body casting of an integral multi-way valve according to claim 1, wherein the heating temperature of the main core in S2 ranges from 150 ° C to 170 ° C, the sand injection pressure is not less than 0.6 MPa, and the sand shooting time. Not less than 6s, the curing time is not less than 120s.