Forging method for large forge piece with conical plate

Abstract

The invention discloses a forging method for a large forge piece with a conical plate, particularly relates to an upsetting tool for designing and manufacturing the conical plate with the conical angle of 135 degrees, and solves the problems that an existing flat anvil is difficult to deform during upsetting, cracks are easily generated in the forge piece and the like. Specifically, the steel ingot is heated to the forging temperature, and the ingot body height and diameter of the steel ingot are controlled as the technological parameters; the preset steel ingot blank is placed in a special conical plate upsetting tool to be subjected to upsetting, and the height-diameter ratio of the upset steel ingot is controlled to range from 0.5 to 1.0; and then the upsetting face is flattened through an ultra-wide anvil. And process parameters such as the material width ratio, the rolling reduction and the anvil width ratio are controlled to be adjusted, and the steel ingot is drawn to the required forge piece size. By means of the method, difficult-to-deform areas can be reduced, easy-to-deform areas can be increased, looseness and cavities in the steel ingot can be forged in the subsequent drawing-out process, the defects in a forged piece are overcome, the rejection rate of materials and the production cost are reduced, and the production efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of forging, and in particular relates to a forging method for a large forging with a conical plate. Background Art

[0002] Large forgings are important pillars of large equipment in metallurgy, electric power, petroleum, chemical industry, mining, transportation industry and atomic energy industry. Therefore, it is of great significance to improve the quality of large forgings and ensure their safety and reliability during operation. In the free forging process of large forgings, upsetting is the most common basic process. At present, the common forging methods of large forgings are generally FM method and WHF method (wide anvil strong pressure forging method) and ultra-wide flat anvil compaction method. FM forging method is a process method of free forging deformation with flat anvil on the top and large platform on the bottom. WHF forging method uses upper and lower wide flat anvils and large reduction rate. In order to ensure the compressive stress state and sufficient deformation of the core of the billet, the anvil width ratio should reach 0.68-0.77, and the reduction rate should be at least 20% each time. The advantage of FM method is that it can produce large tonnage forgings with small tonnage presses. The disadvantage is that the anvil is narrow and the forging penetration performance is poor. The advantage of WHF method is good forging penetration performance, but when the reduction is large, the surface will form fractures. The extra-wide anvil has good forging performance and will not cause breakage. However, when the pressing amount is large, the contact area will increase, and the required tonnage of the press will also increase.

[0003] The main problems in the above-mentioned traditional upsetting process are: there is a difficult deformation zone in the forging process where the anvil contacts, and this difficult deformation zone can only be solved by rotating 90° forging. The deformation amount of the core of the billet and the difficult deformation zone is quite different, and the core is prone to tensile stress. The friction between the anvil and the end face of the billet causes the side of the billet to be drum-shaped, which is easy to generate circumferential tensile stress. Once the tensile stress reaches the material damage limit, cracks will occur and the forging will be scrapped. The most fundamental reason for these problems is the uneven deformation in the traditional upsetting process.

[0004] Conventional forging methods cannot effectively solve the above problems, while conical plate upsetting can effectively solve the inclusion microcracks caused by shear force in the core of the forging. The conical plate upsetting method is to first use a conical upsetting plate to upset the blank. The shape of the conical upsetting plate is certain, and the amount of pressure reduction is in a certain proportion to the height of the blank. Then the same process is performed on the riser end. This process can improve the internal stress state of the forging and force the difficult deformation area of ​​the blank to participate in the deformation. After using the conical plate, during the forging process, the difficult deformation area is reduced, the easy deformation area is increased, and the work efficiency is improved. Second, according to forging theory, there must be an anvil width ratio during the forging process. It is most appropriate to calculate the widest anvil when producing. As the pressure reduction increases, the height decreases, and the width of the anvil has exceeded the range of the optimal anvil width ratio. The 135° conical plate can reasonably solve this problem. Summary of the invention

[0005] The main purpose of the present invention is to provide a method for forging large forgings with a tapered plate according to the current development trend in the field of flat anvil upsetting forging technology. The present invention has a simple process, uses a tapered plate upsetting method to upset large forgings, reduces the difficult deformation area, increases the easy deformation area, determines the tapered plate angle to be 135° according to the anvil width within the optimal anvil width ratio range, and the upset forging is subsequently stretched through an ultra-wide anvil, which can forge the looseness and voids inside the steel ingot, eliminate the internal defects of the forging, improve the internal metal structure of the forging, greatly reduce the scrap rate of the forging, and improve the work efficiency. It can be widely used in the large forging industry.

[0006] In order to solve the technical problems existing in the existing upsetting method, the present invention provides a forging method for a large forging with a tapered plate, comprising the following steps:

[0007] 1. Design and manufacture a special tool for upsetting, wherein the special tool for upsetting is a conical upsetting plate.

[0008] 2. Place the heated steel ingot in a special upsetting tool in the working condition of the press equipment, and place the conical upsetting plate under the workpiece. The press applies a load to the workpiece to upset the steel ingot. After upsetting, the height-to-diameter ratio of the workpiece is controlled between 0.5 and 1.0. Remove the workpiece and use a flat anvil to flatten the upsetting end face by local rolling.

[0009] 3. The steel ingot is widened and elongated. Due to its large height and small length, the entire forging can be fully covered by an extra-wide anvil, and no breakage will occur even if a large amount of pressure is applied.

[0010] 4. During the pressing process, when the contact area is small, the effect is the FM method. If the pressing continues to increase, the contact area will increase, and the effect is the WHF method. If the pressing continues, the contact area will be larger, and the effect is the ultra-wide anvil method. Reverse 180° and press once, which can forge the looseness and voids inside the ingot, and return to the furnace for heating to further weld the forged looseness and voids.

[0011] 5. The process parameters of anvil width ratio, reduction rate and material width ratio during ingot widening and lengthening are as follows:

[0012] The friction coefficient between the anvil and the forging is 0.2~0.8, the anvil width ratio is 0.5~0.8, the reduction is 14%~20%, and the material width ratio is 0.7~1.0.

[0013] The forging method of a large forging with a tapered plate of the present invention has the following advantages and beneficial effects:

[0014] 1. The present invention adopts a special tooling for upsetting a tapered plate for upsetting, and controls the parameters of the billet's height-to-diameter ratio, material width ratio, reduction rate, and anvil width ratio during elongation, so that the difficult-to-deform area of ​​the steel ingot is reduced during the forging process, the easy-to-deform area is increased, the tensile stress in the deformation area of ​​the billet core is controlled, and the circumferential tensile stress caused by the drum shape on the side of the billet is controlled, thereby improving the stress state of the billet core, making the stress state of the core subject to three-way compressive stress, thereby preventing cracks caused by tensile stress inside the billet and avoiding material cracking.

[0015] 2. When the present invention covers the entire forging with an ultra-wide anvil for drawing, the looseness and voids inside the ingot can be forged together, the internal defects of the blank can be eliminated, the metal structure inside the blank can be improved, the scrap rate of the forging can be greatly reduced, the production cost can be reduced, and the work efficiency can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 These are examples of the shape and dimensions of the tapered plate used in the upsetting method with a tapered plate.

[0017] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work. DETAILED DESCRIPTION

[0019] In order to more clearly understand the above-mentioned objectives, features and advantages of the present invention, the scheme of the present invention will be further described below. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0020] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein; the embodiments in the specification are only part of the embodiments of the present invention, rather than all of the embodiments.

[0021] The cone angle of the conical upsetting plate is set to 135°, the finished forging specifications are 4100mm long × 2700mm wide × 800mm high, the design billet specifications are 6300mm high × 3500mm in diameter, and the height-to-diameter ratio is 1.8. First, the steel ingot is heated to the forging temperature, and the ingot body height and diameter are controlled to the ingot body process design height, height H = 6300mm, diameter D = 3500mm, and height-to-diameter ratio H / D = 1.80;

[0022] In the step of upsetting the steel ingot, the preset steel ingot blank is placed in a special tooling for conical plate upsetting, and a press applies a load to the blank to press the steel ingot down to a height of 2100 mm with an average diameter of 3503 mm. The height-to-diameter ratio of the steel ingot after upsetting is 0.6. Then the conical upsetting plate is removed, and the upsetting surface is flattened by a local rolling method using an extra-wide anvil.

[0023] After upsetting, the steel ingot is stretched and stretched to the finished product specifications of 4100mm in length × 2700mm in width × 800mm in height. Due to the large height and small length, the entire forging is covered with an extra-wide anvil, and there will be no breakage even if the amount of pressure is large. During the pressing process, when the contact area is small, the FM method is used. If the pressure continues to increase, the contact area increases, which is the WHF method. If the pressure continues, the contact area will increase, which is the extra-wide anvil method. Reverse 180° and press once to forge the looseness and voids inside the steel ingot, return to the furnace for heating, and further weld the forged looseness and voids.

[0024] A forging method for a large forging with a tapered plate of the present invention specifically comprises the following steps:

[0025] 1. Design and manufacture a special tool for upsetting, wherein the special tool for upsetting is a conical upsetting plate.

[0026] 2. Place the heated steel ingot in a special upsetting tool in the working condition of the press equipment, and place the conical upsetting plate under the workpiece. The press applies a load to the workpiece to upset the steel ingot. After upsetting, the height-to-diameter ratio of the workpiece is controlled between 0.5 and 1.0. Remove the workpiece and use a flat anvil to flatten the upsetting end face by local rolling.

[0027] 3. The steel ingot is widened and elongated. Due to its large height and small length, the entire forging can be fully covered by an extra-wide anvil, and no breakage will occur even if a large amount of pressure is applied.

[0028] 4. During the pressing process, when the contact area is small, the effect is the FM method. If the pressing continues to increase, the contact area will increase, and the effect is the WHF method. If the pressing continues, the contact area will be larger, and the effect is the ultra-wide anvil method. Reverse 180° and press once, which can forge the looseness and voids inside the ingot, and return to the furnace for heating to further weld the forged looseness and voids.

[0029] 5. The process parameters of anvil width ratio, reduction rate and material width ratio during ingot widening and lengthening are as follows:

[0030] The friction coefficient between the anvil and the forging is 0.2~0.8, the anvil width ratio is 0.5~0.8, the reduction is 14%~20%, and the material width ratio is 0.7~1.0.

[0031] The specific embodiments of the present invention are described in detail below:

[0032] Embodiment 1

[0033] The finished forging specification of Example 1 of the present invention is 4100 mm long × 2700 mm wide × 800 mm high, the material is H13, and the non-destructive testing of the forging adopts Part 15 of GB / T 37400.15-2019.

[0034] A forging method for a large forging with a tapered plate according to a first embodiment of the present invention specifically comprises the following steps:.

[0035] 1. Design special upsetting tooling, which includes a tapered upsetting plate at the bottom. The tapered angle of the upsetting plate is determined to be 135° according to the optimal anvil width ratio range of the blank. According to the finished forging product specifications, the process design height and diameter of the ingot body are determined.

[0036] 2. Heat the steel ingot to the required forging temperature, the billet height H = 6300mm and the diameter D = 3500mm, and preform the steel ingot to a height-to-diameter ratio between 1.75 and 2.0.

[0037] 3. Upsetting the steel ingot: Place the pre-set blank in a special tooling for upsetting a conical plate, apply load to the blank by a press, and upset the steel ingot to a height of 2100 mm and an average diameter of 3503 mm. The height-to-diameter ratio of the steel ingot after upsetting is controlled between 0.5 and 1.0. Remove the blank and use an extra-wide anvil to locally roll and flatten the upsetting end surface.

[0038] 4. For the ingot stretching, the press uses an extra-wide anvil to widen and stretch the ingot to the required forging. A large amount of pressure will not cause any breakage. During the pressing process, when the contact area is small, the FM method is used. If the pressure continues to increase, the WHF method is used to increase the contact area. If the pressure continues to increase, the extra-wide anvil method is used. Reverse 180° and press once to forge the looseness and voids inside the ingot. Return to the furnace for heating to further weld the forged looseness and voids, and trim the ingot to 4100mm×2700mm wide×800mm high.

[0039] The sampling pass rate of forgings forged by a large forging method with a tapered plate in embodiment 1 of the present invention is above 90%. After flaw detection, more than 87% of the workpieces have noises below 20% and are defect-free, meeting standard requirements.

[0040] The present invention discloses a method for forging large forgings with a tapered plate. It can be seen from the embodiments that the qualified rate of forgings obtained by forging the present invention is very high, there are few defects inside the forgings, the metal structure of the forgings is improved, and the standard requirements are met. Therefore, the forgings prepared by the forging method with a tapered plate have excellent performance.

Claims

1. A method for forging a large forging with a tapered plate, characterized in that: A special tooling for upsetting a conical plate is designed and manufactured, and the special tooling for upsetting includes a lower conical upsetting plate, and the cone angle of the conical upsetting plate is determined according to the following method: calculated according to forging theory and based on the anvil width ratio in the forging process, the anvil width ratio decreases with the height of the pressing amount, and the width of the anvil exceeds the range of the optimal anvil width ratio. Using a 135° conical plate can reasonably solve this problem.

2. A method for forging a large forging with a tapered plate, characterized in that: The following steps are involved: (1) Designing and manufacturing a special upsetting tool, wherein the special upsetting tool comprises a tapered upsetting plate at a lower portion, wherein the tapered angle of the upsetting plate is determined to be 135° according to an optimal anvil width ratio range of the blank.

3. (2) Heat the steel ingot to the required forging temperature, preform the steel ingot body height H and diameter D, and preform the steel ingot to a height-to-diameter ratio between 1.75 and 2.

0.

4. (3) Upsetting the steel ingot: Place the pre-set blank in a special tooling for upsetting the conical plate, and use a press to apply a load to the blank to upset the steel ingot. The height-to-diameter ratio of the steel ingot after upsetting is controlled between 0.5 and 1.

0. Remove the blank and use an extra-wide anvil to locally roll and flatten the upsetting end surface.

5. (4) When the steel ingot is stretched, an extra-wide anvil is used on the press to widen and stretch the steel ingot to the required forging size. A large amount of pressure will not cause any breakage. During the pressing process, when the contact area is small, the FM method is used. When the pressure continues to increase, the WHF method is used to increase the contact area. When the pressure continues to increase, the extra-wide anvil method is used. The press is reversed 180° and the looseness and voids inside the steel ingot are forged together. The steel ingot is then returned to the furnace for heating to further weld the forged looseness and voids together.

6. A method for forging a large forging with a tapered plate according to claim 1, characterized in that: Using a conical plate for upsetting can effectively solve the problem that the difficult-to-deform area where the blank contacts the anvil can only be forged by rotating 90°. After using the conical plate, the difficult-to-deform area is reduced and the easy-to-deform area is increased during the forging process.

7. A method for forging a large forging with a tapered plate according to claim 1, characterized in that: The taper angle is designed to be 135° according to the range of the optimal anvil width ratio, so that the anvil width is within the range of the optimal anvil width ratio.

8. A method for forging a large forging with a tapered plate according to claim 1, characterized in that: When the forging is stretched after upsetting, an extra-wide anvil is used to cover the entire forging, so that no breakage will occur even when the amount of pressure is large.

9. A method for forging a large forging with a tapered plate according to claim 1, characterized in that: During the pressing process, when the contact area is small, the effect is the FM method. If the pressing continues to increase and the contact area increases, the effect is the WHF method. If the pressing continues and the contact area is further reduced, the effect is the super-wide anvil method. Reverse 180° and press once to forge the looseness and voids inside the ingot. Return to the furnace for heating to further weld the forged looseness and voids.

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