Valve rod nut made of novel composite material and casting and machining production process of valve rod nut

Abstract

The invention discloses a novel composite material valve-stem nut and a casting and machining production process thereof, the internal material of the valve-stem nut is high-nickel nodular cast iron, the external material of the valve-stem nut is common nodular cast iron, and the casting and machining production process comprises a blank casting stage and a finished product machining stage. The valve rod nut and the casting and machining production process thereof have the advantage that the cost is greatly reduced on the premise that the main performance is not reduced.

Description

Technical Field

[0001] The invention relates to the field of valve stem nuts, in particular to a valve stem nut made of a novel composite material and a casting and machining production process thereof. Background Art

[0002] The valve stem nut is a transmission nut in the valve. The internal trapezoidal thread connects the valve stem and rotates and rubs to drive the valve stem to move up and down, and then drives the gate or valve disc connected to the valve stem to move up and down to open and close the valve. The internal trapezoidal thread is the key part of the valve stem nut. The corrosion resistance / wear resistance / self-lubricating property / high and low temperature resistance of the material determines its use environment and life. The external part is the connection nut gland / handwheel / cap, which does not move relative to each other, so the material requirements are not high.

[0003] At present, pure high-nickel ductile iron is generally used for valve stem nuts, but the cost is high due to the high material price and difficulty in machining. Therefore, the main purpose of the present invention is to develop a new composite material valve stem nut without affecting the main performance and reducing the cost. Summary of the invention

[0004] The technical problem to be solved by the present invention is that currently the valve stem nut is generally made of pure high-nickel ductile iron, but due to the high price of the material and the difficulty of machining, the cost is high.

[0005] In order to solve the above technical problems, a technical solution adopted by the present invention is: to provide a valve stem nut made of a new composite material and its casting and machining production process, wherein the internal material of the valve stem nut is high-nickel ductile iron, and the external material of the valve stem nut is ordinary ductile iron.

[0006] The casting and machining production process includes two stages: casting the blank and machining the finished product.

[0007] The blank casting stage comprises the following steps:

[0008] A1: Select the coated sand casting process, design and draw the blank drawing Tm according to the finished drawing Tc of the valve stem nut to be produced, and decompose the shape and size Tm1 of the internal high-nickel ductile iron part and the shape and size Tm2 of the external ductile iron part;

[0009] A2: Design and manufacture the coated sand mold M1 according to the internal blank drawing Tm1 of the valve stem nut;

[0010] A3: Use the coated sand mold M1, install it on the injection molding machine, produce the coated sand mold F1, cast the high-nickel ductile iron molten iron, and cast the high-nickel ductile iron blank n;

[0011] A4: High nickel ductile iron blank n, after inspection, select qualified parts for standby;

[0012] A5: Use qualified high-nickel ductile iron n as the internal casting core to cast the external ductile iron part of the valve stem nut, and fuse them to form an integral composite material valve stem nut casting blank N;

[0013] A6: Design and manufacture the coated sand mold M2 according to the valve stem nut blank drawing Tm, the external blank drawing Tm2 and the internal blank drawing Tm1;

[0014] A7: Use the coated sand mold M2, install it on the injection molding machine, and produce the coated sand mold F2;

[0015] A8: High nickel ductile iron n is loaded into F2 as the internal casting core, and then ductile iron molten iron is cast to fuse to form an integral composite material valve stem nut blank N.

[0016] The machining process includes the following steps:

[0017] B1: Processing the external ductile iron part of the valve stem nut: Since ductile iron is easier to cut than high-nickel ductile iron, it can be produced using ordinary turning and milling compound CNC machine tools, and the qualified external dimensions can be processed according to the drawing Tc;

[0018] B2: Processing the high-nickel ductile iron part inside the valve stem nut: Use precision CNC lathe to process and process the qualified internal dimensions according to drawing Tc.

[0019] The beneficial effects of the present invention are as follows:

[0020] The new composite material valve stem nut is divided into external material and internal material. The external material is made of ordinary ductile iron, which reduces material cost and machining cost; the internal material is made of high-nickel ductile iron, which has corrosion resistance / wear resistance / self-lubricating property / high and low temperature resistance, achieving the main technical indicators of valve stem nuts and reducing costs. DETAILED DESCRIPTION

[0021] The preferred embodiments of the present invention are described in detail below so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0022] The inner material of the stem nut is made of high nickel ductile iron, and the outer material of the stem nut is made of ordinary ductile iron.

[0023] The casting and machining production process includes two stages: casting the blank and machining the finished product.

[0024] The blank casting stage includes the following steps:

[0025] A1: Select the coated sand casting process, design and draw the blank drawing Tm according to the finished drawing Tc of the valve stem nut to be produced, and decompose the shape and size Tm1 of the internal high-nickel ductile iron part and the shape and size Tm2 of the external ductile iron part;

[0026] A2: Design and manufacture the coated sand mold M1 according to the internal blank drawing Tm1 of the valve stem nut;

[0027] A3: Use the coated sand mold M1, install it on the injection molding machine, produce the coated sand mold F1, cast the high-nickel ductile iron molten iron, and cast the high-nickel ductile iron blank n;

[0028] A4: High nickel ductile iron blank n, after inspection, select qualified parts for standby;

[0029] A5: Use qualified high-nickel ductile iron n as the internal casting core to cast the external ductile iron part of the valve stem nut, and fuse them to form an integral composite material valve stem nut casting blank N;

[0030] A6: Design and manufacture the coated sand mold M2 according to the valve stem nut blank drawing Tm, the external blank drawing Tm2 and the internal blank drawing Tm1;

[0031] A7: Use the coated sand mold M2, install it on the injection molding machine, and produce the coated sand mold F2;

[0032] A8: High nickel ductile iron n is loaded into F2 as the internal casting core, and then ductile iron molten iron is cast to fuse to form an integral composite material valve stem nut blank N.

[0033] The machining process for the finished product consists of the following steps:

[0034] B1: Processing the external ductile iron part of the valve stem nut: Since ductile iron is easier to cut than high-nickel ductile iron, it can be produced using ordinary turning and milling compound CNC machine tools, and the qualified external dimensions can be processed according to the drawing Tc;

[0035] B2: Processing the high-nickel ductile iron part inside the valve stem nut: Use precision CNC lathe to process and process the qualified internal dimensions according to drawing Tc.

[0036] The advantage of the invention is that the cost is greatly reduced without reducing the main performance, which is specifically reflected in two aspects:

[0037] Material cost:

[0038] The new composite material valve stem nut, the outer ductile iron accounts for 80%, the inner high nickel ductile iron accounts for 20%, the current cost of high nickel ductile iron is 50 yuan / kg, the cost of ductile iron is 8 yuan / kg, assuming that the blank weight of the valve stem nut is 1 kg, then the blank cost of pure high nickel ductile iron valve stem nut = 1 kg × 50 yuan / kg = 50 yuan, and the blank cost of the new composite material valve stem nut = 0.2 kg × 50 + 0.8 kg × 8 yuan / kg = 16.4 yuan, 16.4÷50×100% = 32.8%

[0039] According to the above calculation results, the cost of the new composite valve stem nut blank is only 32.8% of that of pure high-nickel ductile iron.

[0040] Processing cost:

[0041] Ductile iron is easier to cut than high-nickel ductile iron. The external dimension processing fee of 1 kg of pure high-nickel ductile iron stem nut is 5 yuan / piece, and the internal dimension processing fee is 5 yuan / piece, totaling 10 yuan / piece; the external dimension processing fee of 1 kg of new composite material stem nut is 2.5 yuan / piece, and the internal dimension processing fee is 5 yuan / piece, totaling 7.5 yuan, 7.5÷10×100%=75%.

[0042] Comprehensive cost:

[0043] (16.4+7.5)÷(50+10)×100%=39.8%

[0044] In summary, the cost of the new composite valve stem nut is only 39.8% of that of pure high-nickel ductile iron.

[0045] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the specification of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A new type of composite material valve stem nut, characterized in that: The inner material of the valve stem nut is high-nickel ductile iron, and the outer material of the valve stem nut is ordinary ductile iron.

2. A new composite material valve stem nut casting and machining production process, characterized in that: The casting and machining production process includes two stages: casting the blank and machining the finished product.

3. The casting and machining production process according to claim 2, characterized in that: The blank casting stage comprises the following steps: A1: Select the coated sand casting process, design and draw the blank drawing Tm according to the finished drawing Tc of the valve stem nut to be produced, and decompose the shape and size Tm1 of the internal high-nickel ductile iron part and the shape and size Tm2 of the external ductile iron part; A2: Design and manufacture the coated sand mold M1 according to the internal blank drawing Tm1 of the valve stem nut; A3: Use the coated sand mold M1, install it on the injection molding machine, produce the coated sand mold F1, cast the high-nickel ductile iron molten iron, and cast the high-nickel ductile iron blank n; A4: High nickel ductile iron blank n, after inspection, select qualified parts for standby; A5: Use qualified high-nickel ductile iron n as the internal casting core to cast the external ductile iron part of the valve stem nut, and fuse them to form an integral composite material valve stem nut casting blank N; A6: Design and manufacture the coated sand mold M2 according to the valve stem nut blank drawing Tm, the external blank drawing Tm2 and the internal blank drawing Tm1; A7: Use the coated sand mold M2, install it on the injection molding machine, and produce the coated sand mold F2; A8: High nickel ductile iron n is loaded into F2 as the internal casting core, and then ductile iron molten iron is cast to fuse to form an integral composite material valve stem nut blank N.

4. The casting and machining production process according to claim 2, characterized in that: The machining process includes the following steps: B1: Processing the external ductile iron part of the valve stem nut: Since ductile iron is easier to cut than high-nickel ductile iron, it can be produced using ordinary turning and milling compound CNC machine tools, and the qualified external dimensions can be processed according to the drawing Tc; B2: Processing the high-nickel ductile iron part inside the valve stem nut: Use precision CNC lathe to process and process the qualified internal dimensions according to drawing Tc.