Flat die for thread rolling

Abstract

To provide a flat die for thread rolling that ensures the lifespan of the flat die while eliminating the large diameter difference between the left and right sides of the workpiece during thread rolling. [Solution] A flat die for rolling, having a feeding section with multiple feeding teeth that perform the initial rolling process on the workpiece, and a finishing section formed continuously with the feeding section and having multiple finishing teeth, wherein the feeding teeth have front feeding teeth and rear feeding teeth formed between the front feeding teeth and the finishing teeth, the front feeding teeth are formed with at least an increase in tooth thickness and a decrease in tooth root as they move toward the rear feeding teeth, and the rear feeding teeth are formed with at least an increase in tooth height and a decrease in tooth root as they move toward the finishing teeth.

Description

Technical Field

[0005]

[0001] The present invention relates to a flat die for swaging used during swaging of gears and the like.

Background Art

[0002] Conventionally, in swaging using a flat die for swaging, it is known that the large-diameter dimension differs between the tooth surfaces on the left and right sides due to differences in the flow of the metal flow of the workpiece. In Patent Document 1, the large-diameter dimension is suppressed by making the die tooth root into two steps up to about half of the tooth height during swaging, and in the latter half of the swaging, the tooth root is relieved to stop suppressing the large diameter, and the large diameter is suppressed again with the tooth root of the flat die for swaging with the finishing teeth, thereby disclosing a swaging technique for reducing the dimensional difference between the left and right sides.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the swaging method disclosed in Patent Document 1, although the dimensional accuracy of the workpiece can be ensured, there is a problem that tooth chipping occurs in the initial stage of swaging, and the life of the flat die for swaging is significantly shortened.

[0005] For example, schematic diagrams of the swaging form using a conventional flat die for swaging are shown in FIGS. 6 to 8 respectively. First, in order to suppress the left-right difference in the large-diameter dimension during swaging, as shown in FIGS. 6 and 7, the tooth root of the flat die for swaging escapes from the large diameter of the workpiece in the first half and the second half of the biting part. Thereafter, as shown in FIG. 8, the large diameter of the workpiece is suppressed with the finishing teeth to improve the left-right difference in the large diameter, but the load on the finishing teeth increases, making the machining teeth prone to chipping, and ultimately there is a problem that the life of the flat die for swaging is shortened to 1 / 3 to 1 / 4.

[0006] Therefore, the object of the present invention is to provide a flat die for rolling that ensures the lifespan of the flat die for rolling while eliminating the large diameter difference on both the left and right sides of the workpiece during rolling. [Means for solving the problem]

[0007] The present invention provides a flat die for rolling, comprising: a cutting section having a plurality of cutting teeth that perform the initial rolling process on a workpiece; and a finishing section formed continuously with the cutting section and having a plurality of finishing teeth, wherein the cutting teeth comprise front cutting teeth and rear cutting teeth formed between the front cutting teeth and the finishing teeth, and the front cutting teeth are formed with at least an increase in tooth thickness and a decrease in tooth root as they move toward the rear cutting teeth, and the rear cutting teeth are formed with at least an increase in tooth height and a decrease in tooth root as they move toward the finishing teeth. [Effects of the Invention]

[0008] The present invention provides a flat die for rolling, comprising a cutting section with a plurality of cutting teeth that perform the initial rolling process on the workpiece, and a finishing section formed continuously with a plurality of finishing teeth, wherein the cutting teeth include front cutting teeth and rear cutting teeth formed between the front cutting teeth and the finishing teeth, and the front cutting teeth are formed with at least an increase in tooth thickness and a decrease in tooth root as they move toward the rear cutting teeth, and the rear cutting teeth are formed with at least an increase in tooth height and a decrease in tooth root as they move toward the finishing teeth, thereby ensuring the lifespan of the flat die for rolling while eliminating the large diameter difference between the left and right sides of the workpiece during rolling. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram of the shape of the machining teeth of a flat die for thread rolling, which is one embodiment of the present invention. [Figure 2] This is a schematic diagram of the rolling process using the front cutting teeth of a flat die for rolling. [Figure 3]This is a schematic diagram of the rolling process using the rear cutting teeth of a flat die for rolling. [Figure 4] This is a schematic diagram of the rolling process using the finishing teeth of a flat die for rolling. [Figure 5] This shows the tooth profile shape of the workpiece as a result of the rolling process test in the example. [Figure 6] This is a schematic diagram of a conventional rolling process using a flat die with forward-cutting teeth. [Figure 7] This is a schematic diagram of a conventional rolling process using a flat die with rear cutting teeth. [Figure 8] This is a schematic diagram of a conventional rolling process using the finishing teeth of a flat die for rolling. [Modes for carrying out the invention]

[0010] An embodiment of the flat die for rolling according to the present invention will be described with reference to the drawings. A schematic diagram is shown in Figure 1. As shown in Figure 1, the rolling of gears using the flat die for rolling according to the present invention is formed from three main types of processing: tooth height increase, tooth thickness increase, and tooth root decrease. Next, the details of these three types of rolling processes will be described. A schematic diagram of the rolling process using the front cutting teeth of the flat die for rolling is shown in Figure 2, a schematic diagram of the rolling process using the rear cutting teeth of the flat die for rolling is shown in Figure 3, and a schematic diagram of the rolling process using the finishing teeth of the flat die for rolling is shown in Figure 4.

[0011] First, the flat die for thread rolling according to the present invention has a feeding section equipped with a plurality of feeding teeth that perform the initial thread rolling on the workpiece, and a finishing section formed continuously with the feeding section and equipped with a plurality of finishing teeth. The feeding teeth are formed from anterior feeding teeth and posterior feeding teeth. The anterior feeding teeth are formed with at least an increase in tooth thickness and a decrease in tooth root as they move toward the posterior feeding teeth. Similarly, the posterior feeding teeth are formed with at least an increase in tooth height and a decrease in tooth root as they move toward the finishing teeth. Each thread rolling process using the anterior feeding teeth, posterior feeding teeth, and finishing teeth will be described below.

[0012] <Forward nibbling machining> The forward nibbling teeth are responsible for rough machining in the initial stage of the workpiece. Their role is mainly to roughly forge the workpiece material. Depending on the arrangement and shape of the forward nibbling teeth, while gradually increasing the tooth height of the workpiece, the tooth root of the workpiece material is pressed and crushed as necessary. In this process, the basic contour of the tooth profile is formed, laying the foundation for subsequent machining processes. The forward nibbling teeth are specially designed to achieve high-speed and high-precision machining, and their tooth profile can be optimized to minimize material deformation during machining.

[0013] <Backward nibbling machining> The backward nibbling teeth play the role of further precisely forging the workpiece that has been roughly machined by the forward nibbling teeth. At this stage, the tooth thickness of the workpiece is adjusted, and the tooth root is also finished more precisely. Due to the design of the backward nibbling teeth, the rough tooth profile formed by the forward nibbling teeth is further refined, preparing for the final finish. The backward nibbling teeth play an important role in smoothing the initial tooth profile forged by the forward nibbling teeth and enhancing the overall shape accuracy.

[0014] <Finishing teeth nibbling machining> The finishing teeth are responsible for the final finishing process and finish the final shape of the workpiece with high precision. At this stage, the tooth profile of the workpiece is completely formed, achieving the desired dimensional accuracy and surface finish. Due to the precise shape and arrangement of the finishing teeth, the surface of the workpiece becomes smooth, ensuring the required strength and durability. The machining by the finishing teeth is the final process to further improve the machining accuracy in the previous stage and is essential for guaranteeing the quality of the product.

Example

[0015] Next, a forging machining test (hereinafter referred to as this test) was conducted using two types of flat dies for forging machining according to the present invention (hereinafter referred to as the invention product) and a conventional flat die for forging machining (hereinafter referred to as the conventional product). Therefore, the test results will be described using the drawings.

[0016] The invention product used in this test is a flat die for forging, shown in FIGS. 1 to 4, that is, a biting portion having a plurality of biting teeth for first performing forging on a workpiece, and a flanging portion continuously formed on the biting portion and having a plurality of finishing teeth. The biting teeth are formed from front biting teeth and rear biting teeth. The front biting teeth are formed such that at least the tooth thickness increases and the tooth bottom decreases as it goes toward the rear biting teeth side, and the rear biting teeth are formed such that at least the tooth height increases and the tooth bottom decreases as it goes toward the finishing teeth side. It is a flat die for forging.

[0017] On the other hand, as shown in FIGS. 6 to 8, the conventional product shows schematic diagrams of the forging processing forms by conventional flat dies for forging in FIGS. 6 to 8 respectively. First, in order to suppress the left-right difference in the large-diameter dimension during forging, as shown in FIGS. 6 and 7, a flat die for forging is provided with a gap in which the tooth bottom of each processing tooth in the first half and the second half of the biting portion can escape from the large diameter of the workpiece. As a common specification for the invention product and the conventional product, the overall length is 42 inches and the material is high-speed tool steel.

[0018] The forging processing conditions in this test were as follows. · Material of the workpiece: Chrome manganese steel · Module of the workpiece: 1.058 · Number of teeth of the workpiece: 20 · Pressure angle of the workpiece: 30° · Forging width: 25 mm · Forging speed: 10 m / min · Lubricant type: Oil-based lubricant

[0019] After this test was completed, the tooth profile shape of the large-diameter portion of the workpiece was measured and the shape of the tip was confirmed.The measurement results of the tooth profile shape are shown in FIG. 5. As a result of measuring the burr height of the workpiece (work) forged using the conventional product, it was found to be 0.214 mm as shown in FIG. 5. On the other hand, no burr (large-diameter burr) was confirmed on the workpiece forged using the invention product. Also, the total number of workpieces processed by forging using the conventional product was 40,000, while the total number of workpieces processed by forging using the invention product was 50,000.

[0020] Based on the above test results, the cutting portion of the flat die for rolling according to the present invention is formed such that the front cutting teeth increase in thickness and the tooth root decreases as they move toward the rear cutting teeth, and the rear cutting teeth increase in height and the tooth root decreases as they move toward the finishing teeth. Therefore, it was found that this suppresses the generation of burrs on the workpiece and simultaneously reduces the processing load during the rolling process by the finishing section, which in turn leads to an improvement in the lifespan of the flat die used for rolling.

Claims

[Claim 1] A flat die for rolling, comprising a feeding section having a plurality of feeding teeth that perform the initial rolling process on a workpiece, and a finishing section formed continuously with the feeding section and having a plurality of finishing teeth, wherein the feeding teeth have front feeding teeth and rear feeding teeth formed between the front feeding teeth and the finishing teeth, and the front feeding teeth are formed with at least an increase in tooth thickness and a decrease in tooth root as they move toward the rear feeding teeth, and the rear feeding teeth are formed with at least an increase in tooth height and a decrease in tooth root as they move toward the finishing teeth.

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