JPS6343175B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to warm and hot forging of steel, and uses a dispersion liquid in which calcium sulfate or barium sulfate, which is a new lubricant, is uniformly dispersed in an aqueous solution of colloidal graphite. By spraying the dispersion onto the mold at a predetermined injection pressure, the extrusion depth ratio (l/
d) Two or more warm/hot forgings are possible. Cold forging is currently widely used as a forming method that provides high dimensional accuracy, but although it provides high accuracy, it has high deformation resistance and limits the forming shape. Recently, warm forging has been attracting attention as a method to solve these problems. Generally, during warm forging, a lubricant film is formed by a tumbler method, a dipping method, etc. after pretreatment such as pickling and shotplast to make it easier for lubricant to adhere to the workpiece. The forging process is performed by heating to a temperature of . For carbon steel, low-alloy steel, etc., when the workpiece is heated during forging, an oxide film is formed on the outermost surface, and the lubricating action of this film helps to eliminate the conventionally used graphite and molybdenum disulfide. Warm forging was possible to some extent even with lubricants such as. However, in machining involving an extrusion depth ratio (l/d) of 2 or more and a large increase in surface area, the lubricating performance of the above-mentioned lubricants was insufficient and seizure occurred. In addition, graphite molybdenum disulfide and the like undergo significant oxidation at high temperatures of 500°C or higher, and there are significant restrictions on their use, such as processing temperature and heating conditions. The present invention solves the above-mentioned drawbacks by finding conditions for obtaining the best lubrication performance regarding the composition of the dispersion liquid sprayed to lubricate the mold, the mold temperature, the spray injection pressure, etc. The purpose of the present invention is to provide a warm/hot forging method that does not cause seizure even in processing that involves a large increase in surface area in a high temperature range without any processing. The method of the present invention will be explained in detail below. The dispersion liquid used in the present invention uses a colloidal graphite aqueous solution as a solution that facilitates the adhesion of the lubricant to the mold and the uniform dispersion of the added solid lubricant. For example, even in the hot forging region of about 1250℃, there is almost no oxidation wear or decomposition, and even under high temperature and high pressure, all new surfaces that occur during deformation are protected with a lubricating film. Calcium sulfate or barium sulfate, which can be used as an adhesive and has particularly excellent seizure resistance, was used. Note that calcium sulfate here refers to anhydrite (CaSO ₄ ), hemihydrate gypsum (CaSO ₄・1/2
H ₂ O) dihydrate gypsum (CaSO ₄ 2H ₂ O). The composition of the dispersion liquid and the added lubricant in which good lubrication performance can be obtained is as follows. Its composition consists of a colloidal graphite aqueous solution containing graphite (A) at a weight ratio of 0.5 to 30%, and one or two types of calcium sulfate or barium sulfate (B) having an average particle size of 50μ or less. in comparison
0.1-30% (However, A+B: 35% or less,
and B/A+B×100: 10% or more). The reason for limiting the amount of graphite in the colloidal graphite aqueous solution and the sum of one or two of calcium sulfate or barium sulfate is that the lower limits are set to 0.5% and 0.1% because the lubricating performance is insufficient below this. , and the upper limit exceeds 30% for each, and if the sum of both exceeds 35%, it becomes difficult to form a uniform lubricant film when spray lubrication is applied to the mold, which is not preferable. In the second invention, a lubricant made of calcium sulfate or barium sulfate, and one or more layered solid lubricants such as boron nitride fluoride graphite, molybdenum disulfide, and tungsten disulfide are added in a weight ratio. 0.5-15% (However, A+B+
By uniformly dispersing it in an aqueous colloidal graphite solution so that C: 35% or less and B/A+B+C×100: 10% or more, excellent seizure resistance and a low coefficient of friction can be obtained. It is something. In addition, regarding the mold temperature, when using spray lubrication, the adhesion to the mold is poor at temperatures below 100℃;
If the temperature is above ℃, the spray liquid will repel and a uniform film cannot be formed. Therefore, in order for the dispersion liquid to form a lubricating film of uniform thickness on the mold surface, the mold temperature must be adjusted.
It is necessary to maintain the temperature between 100 and 450℃. In addition, when the degree of processing is large, 150 to 350
It is preferable to set the temperature to ℃. Also, in order to maintain the mold temperature at 100 to 450°C, the amount of lubricant applied is increased or decreased. Furthermore, in some cases, the mold temperature may be adjusted by incorporating a heater or a water cooling jacket into the mold. Regarding the spraying pressure of the dispersion liquid onto the mold, if the spraying pressure is low, it is difficult to form a uniform and dense lubricating film, so it is necessary to set it to 2 kg/cm ² or more. In addition, if the injection pressure is too high, the dispersion liquid will be repelled and the amount of adhesion to the mold will vary, so when spraying lubrication with high-pressure air, it is preferable to set it to 10 kg/cm ² or less, and when spraying lubrication using an airless method, is preferably 100Kg/cm ² or less. Furthermore, regarding the average particle size of calcium sulfate or barium sulfate, if it exceeds 50μ, it will be difficult to uniformly disperse it in the colloidal graphite aqueous solution, and if spray lubrication is used, the nozzle will be easily clogged, so it should be less than 50μ. It is preferable. Next, the first invention will be explained with reference to examples. A 35φ x 35mm specimen of JISS45C and SCM4 was used as the workpiece. The spray lubricant for the mold contains calcium sulfate with an average particle size of 10μ or an average particle size of 10μ as a lubricant.
A dispersion liquid in which 1μ barium sulfate was uniformly dispersed in an aqueous colloidal graphite solution with different composition ratios was used. The mold temperature and spray pressure were changed as appropriate. During forging, an induction heating device is used to heat the workpiece to 300-1000℃, and the processing method is a backward extrusion method that processes the material into a cup shape, with an extrusion depth ratio (l/d) of 2.0-3.0.
The cross-section reduction rate was set to 70%, and the number of processed pieces was 100 each.

【table】

[Table] As shown in Table 1, in the method of the present invention, a dispersion in which calcium sulfate or barium sulfate is added to a colloidal graphite aqueous solution is used as the mold spray liquid, and the mold temperature is 100 to 450°C, and the spray is By setting the pressure within the range of 2 to 100 Kg/cm ² , all pieces could be processed without seizing despite the severe processing conditions of an extrusion depth ratio (l/d) of 2.0 to 3.0. However, in the conventional method, seizure occurred in several pieces of any steel type. This shows that severe machining cannot be performed simply by using a colloidal graphite aqueous solution as a spray lubricant. Also, regarding the comparative method, 30
Burn-in occurs in less than Therefore, it can be seen that good lubrication performance cannot be obtained if the compositions of the dispersion liquid and the added lubricant do not satisfy the compositions of the present invention. Next, the second invention will be explained with reference to examples. A nutacle was manufactured using a JISSCr4 70φ x 200mm specimen as the workpiece. The product shape is shown in Figure 2. Calcium sulfate with an average particle size of 10μ or an average particle size as a spray lubricant for molds
A dispersion was used in which 1μ of barium sulfate was mixed with molybdenum disulfide or boron nitride, which are layered solid lubricants that lower the coefficient of friction, and uniformly dispersed in an aqueous colloidal graphite solution. The material to be processed is heated to 1150℃ using an induction heating device, and the number of pieces processed is
500 pieces.

【table】

[Table] Regarding the overhanging property of the flesh in Table 2, the friction coefficient was evaluated based on the degree of lack of thickness at the R part of the tip of the shaft of the nutacle shown in ^Figure 2. , 2 ^R or more and less than 3 ^R is △, and 3 ^R or more is ×. The results are as shown in Table 2. In order to satisfy the composition of the second invention as a mold spray liquid, calcium sulfate or barium sulfate, molybdenum disulfide, boron nitride,
Using a dispersion with a composite addition of fluorinated graphite, the mold temperature is 100 to 450℃, and the spray pressure is 2 to 100Kg/
By setting it within the range of cm ² , all pieces did not seize despite the severe processing conditions, and the meat extrusion properties were all below 2 ^R , indicating a low coefficient of friction. However, in the comparative method, the anti-seizure property was good when the composition of the added layered solid lubricant was slightly lower, but the radius of the tip of the shaft of the knuckle was 2 to 3 ^R.
It is large and the meat does not stick out well. In addition, if the composition of calcium sulfate or barium sulfate and the composition of the added layered solid lubricant are not satisfactory, seizure will occur in 10 pieces, and the tip R of the shaft will be 3 ^R or more, resulting in poor extension properties. . This indicates that addition of a layered solid lubricant such as boron nitride, graphite fluoride, and molybdenum disulfide improves stretchability and lowers the coefficient of friction. As described above, the present invention does not require complicated lubrication treatment for the workpiece, and the dispersion in which calcium sulfate or barium sulfate, which is an inexpensive lubricant, is uniformly dispersed in an aqueous colloidal graphite solution is heated to a predetermined temperature. By spray lubricating the held mold at a predetermined injection pressure, it is possible to form a uniform and dense lubricating film with excellent seizure resistance on the mold surface, making it possible to perform even under severe processing conditions that were previously considered impossible. It is extremely useful industrially as it enables warm and hot forging, reduces manufacturing costs and improves yield.

[Brief explanation of the drawing]

The drawings show the shapes of the molded products; FIG. 1 shows a cup shape formed by backward extrusion, and FIG. 2 shows a knuckle formed by die forging.

Claims (1)

[Scope of Claims] 1. In a colloidal graphite aqueous solution containing 0.5 to 30% by weight of graphite (A), one or two types of calcium sulfate or barium sulfate (B) having an average particle size of 50μ or less are added. ) is the weight ratio, 0.1 to 30
% (however, A+B: 35% or less and B/A+B×100: 10% or more), and this dispersion was placed in a mold maintained at about 100 to 450°C under an injection pressure of 2. Spray lubricate with ~100Kg/ ^cm2 ,
A warm/hot forging method using mold spray lubrication, which is characterized by forging the heated workpiece at a temperature of 500°C or higher. 2. In a colloidal graphite aqueous solution containing graphite (A) at a weight ratio of 0.5 to 30%, one or the sum of two types (B) of calcium sulfate or barium sulfate with an average particle size of 50 μ or less is added at a weight ratio of 0.1 ~30%,
The sum (C) of one or more layered solid lubricants such as boron nitride, graphite fluoride, molybdenum disulfide, and tungsten disulfide with an average particle size of 50μ or less is 0.5 to 15% by weight (A+B+C: 35% or less and B/A+B+C×100:10% or more), and then heat this dispersion at 100 to 450°C.
The injection pressure is 2 to 100Kg/cm ² to the mold that is maintained at a certain level.
spray lubricate and then heat the workpiece.
Warm/hot forging method using mold spray lubrication, characterized by forging at temperatures of 500°C or higher.