CN110125391B

CN110125391B - Die and method for manufacturing pressed blank with step

Info

Publication number: CN110125391B
Application number: CN201910392611.8A
Authority: CN
Inventors: 曾涛; 王雁洁
Original assignee: ZIGONG CEMENTED CARBIDE CORP Ltd
Current assignee: Chengdu Great Wall Cutting Tools Co ltd; ZIGONG CEMENTED CARBIDE CORP Ltd
Priority date: 2019-05-13
Filing date: 2019-05-13
Publication date: 2022-05-13
Anticipated expiration: 2039-05-13
Also published as: CN110125391A

Abstract

The die comprises a lower punch, a female die and an upper punch, wherein the female die is provided with a die hole penetrating through the female die from top to bottom, the lower end of the upper punch is matched with the female die and can be inserted from the upper end of the die hole, the upper end of the lower punch is matched with the female die and can be inserted from the lower end of the die hole, the lower punch is formed by splicing the left punch and the right punch, and the top of the left punch is higher than the top of the right punch so as to form a stepped pressing surface for pressing a pressed blank with steps. The traditional lower punch with a boss-shaped pressing surface is divided into a left punch and a right punch which are different in height, when the left punch is used, a lifting ejector rod is arranged at the lower part of the left punch, so that the left punch has a certain moving space in the vertical direction, the left punch is lowered to be as high as the right punch in the pressing process by attaching the upper punch, the running height of the left punch is adjusted by the ejector rod, the height difference of raw material powder filled in a female die is changed, and the compression ratio of each part is approximately the same.

Description

Die and method for manufacturing pressed blank with step

Technical Field

The invention belongs to the technical field of hard alloy manufacturing, and particularly relates to a die and a method for manufacturing a pressed blank with a step.

Background

The hard alloy product with the steps can be used for cutting frozen soil excavation or welding cutting tools during geological mine excavation. In the prior art, when manufacturing a hard alloy product with steps, as shown in the attached

drawings

5 and 6 of the specification, raw material powder is firstly pressed into a pressed blank by a die with a step-shaped pressing surface on an inner lower punch, and then the pressed blank is sintered at high temperature, in the pressing process of the die, the lower punch with the step-shaped pressing surface is a fixed whole and cannot move in the pressing process, when the raw material powder is filled in a female die, the height difference exists between the raw material at the position A and the raw material at the position B of the filled powder, when the upper punch moves downwards and presses the raw material powder, the compression ratio of the raw material powder at the position A and the compression ratio of the raw material powder at the position B are different, so that the densities at the position A and the position B of the pressed blank obtained by pressing are different, and in the sintering process, because the density difference exists in the pressed blank, all parts of the sintered hard alloy product with steps shrink inconsistently, the sintered sample deforms, thus not conforming to the shape of the drawing.

Disclosure of Invention

In view of the above problems, an object of the present invention is to provide a die for pressing a stepped complex-shaped cemented carbide product and a method of manufacturing a stepped compact using the same.

In order to achieve the above purpose, the invention adopts the technical scheme that: the die comprises a lower punch, a female die and an upper punch, wherein a die hole penetrating through the female die from top to bottom is formed in the female die, the lower end of the upper punch is matched with the female die and can be inserted into the lower end of the die hole, the upper end of the lower punch is matched with the female die and can be inserted into the lower end of the die hole, the lower punch is formed by splicing a left punch and a right punch, and the top of the left punch is higher than the top of the right punch so as to form a step-shaped pressing surface for pressing a pressed blank with a step.

The invention also provides a method for manufacturing a pressed blank with steps by using the die, which adopts an automatic press to press, such as a powder forming press of S-20A type, wherein a horizontal supporting table is arranged on the press, a vertical hole is arranged on the supporting table, a jacking piece is arranged in the vertical hole, and a pressed block which can be vertically close to or far away from the supporting table is arranged at the upper part of the supporting table, and the method is characterized by comprising the following steps:

step 1, placing a left punch and a right punch on a supporting table of a press, wherein the left punch is positioned at the upper part of a vertical hole, a jacking piece drives the left punch to ascend to the position that the height difference between the top of the left punch and the top of the right punch is larger than the preset step height value of a pressed blank to be manufactured, sleeving a female die from the tops of the left punch and the right punch, controlling the height of the female die to ensure that the inner wall of a die hole of the female die and the tops of the left punch and the right punch form a pressing cavity with a stepped bottom surface, filling powder to be pressed into the pressing cavity, and installing the upper punch on a pressing block and adapting to the female die;

and 2, starting the pressing machine, driving the upper punch to press downwards by a pressing block of the pressing machine, continuously extruding powder in a pressing cavity in the process of pressing the upper punch downwards, so that the powder is pressed and shaped into a pressed blank with a step end, and driving the left punch to synchronously descend by the jacking piece during pressing so that the height difference between the top of the left punch and the top of the right punch is the preset step height value of the pressed blank to be manufactured.

Specifically, the jacking piece is the ejector rod arranged at the lower part of the left punch, the ejector rod is located in a vertical hole of the supporting table, the lower part of the ejector rod is a pneumatic core rod cylinder arranged on the press, the pneumatic core rod cylinder drives the ejector rod to vertically move in the vertical hole in

steps

1 and 2, and the length of the ejector rod is selected according to needs in the pressing blank process.

The invention has the beneficial effects that:

the die and the method for manufacturing the pressed blank with the step, provided by the invention, decompose the traditional lower punch with the boss-shaped pressing surface into the left punch and the right punch with different heights, when in use, the liftable ejector rod is arranged at the lower part of the left punch, so that the left punch has a certain moving space in the vertical direction, the pressing of the upper punch is attached during the pressing process, the left punch is lowered to be as high as the right punch, the operating height of the left punch is adjusted by the ejector rod, the height difference of the female die for filling raw material powder is changed, the compression ratio of each part is close to the same, therefore, the density of each part of the pressed compact tends to be consistent, the sintering shrinkage deformation caused by density difference is reduced, the problem that the density of each part of the pressed compact is not uniform due to the fact that the compression ratio of the filled raw material powder is not consistent in the process of pressing the pressed compact by adopting the die with the step-shaped pressing surface is solved, and the problem of deformation of a sintered product is further solved.

Drawings

FIG. 1 is a mold provided by the present invention;

fig. 2 to 4 are schematic views of a method of manufacturing a green compact using a die;

FIGS. 5 and 6 are schematic diagrams of a pressed blank manufactured by using a conventional die;

wherein, 1 is left towards, 2 is right towards, 3 is the bed die, 4 is the upper punch, 5 is the brace table, 6 is the briquetting, 7 is the ejector pin, 8 is left gland, 9 is right gland, 10 is the upper gland, 11 is the briquetting, 12 is pneumatic core rod cylinder.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

Examples

As shown in fig. 1, the present embodiment provides a die, which includes a lower punch, a female die 3, and an upper punch 4, wherein the female die 3 has a die hole penetrating through the female die 3 from top to bottom, the lower end of the upper punch 4 is adapted to the female die 3 and can be inserted from the upper end of the die hole, the upper end of the lower punch is adapted to the female die 3 and can be inserted from the lower end of the die hole, the lower punch is formed by splicing a left punch 1 and a right punch 2, and the top of the left punch 1 is higher than the top of the right punch 2 to form a stepped pressing surface; the ejector rod 7 is arranged below the left punch 1, and the ejector rod 7 can move vertically and drive the left punch to move in the vertical direction.

Taking the manufacturing of the pressed blank with steps as an example, the height of the pressed blank with steps at the low stage is 10cm, the height of the high stage is 15cm, and the height difference of the steps is 5cm, a die with the height difference of the top of the left punch and the right punch is selected, the compression ratio of the raw material powder is 80%, the die provided by the embodiment is used for manufacturing the pressed blank with steps, a powder forming press of the model S-20A is adopted for pressing, a horizontal support table 5 is arranged on the press, a pressing block 6 which can be vertically close to or far away from the support table 5 is arranged at the upper part of the support table 5, a pneumatic core rod cylinder is arranged at the lower part of the support table, each part of the die is installed by using a die frame arranged on the press, as shown in figure 2, when the die is assembled, the ejector rod 7 is firstly installed on a die frame connecting piece with the pneumatic core rod (floating punch) cylinder, the support table 5 of the press is arranged above the ejector rod 7, a vertical hole for the ejector rod 7 to pass through is arranged on the support table 5, installing a left punch, a right punch and a female die on a support table 5 of a press, fixing the left punch 1 on the upper part of a vertical hole of the support table 5 through a left gland 8, wherein a space for the left punch 1 to vertically move is arranged in the left gland 8, fixing a right punch 2 on the support table 5 through a right gland 9, installing a large plate externally arranged outside the female die 3 and adjusting the tightness degree of a fastening screw to enable the large plate and the surface of the female die 3 to be in the same plane, installing a material pushing box on the large plate, pressing the material pushing box through a pressing cylinder, finally installing an upper punch 4 on a pressing block 6 through the upper punch gland 10, and enabling the upper punch 4 to freely run inside and outside the female die 3 and be fastened through the screw in the upper punch gland 10 when the upper punch is not scratched;

in the pressing process, as shown in fig. 2, a cylinder of a pneumatic core rod (floating punch) of the press is inflated to push the top rod 7 upwards until the height difference between the top of the left punch 1 and the top of the right punch 2 is greater than a preset step height value of a green compact to be manufactured, the height difference between the top of the left punch 1 and the top of the right punch 2 is calculated according to the compression ratio of raw material powder and the preset step height value of the green compact to be pressed, specifically 5 ÷ 80% ~ 6.25cm, the powder to be pressed is filled into a pressing cavity with a stepped bottom surface, which is surrounded by the female die 3 and the tops of the left punch 1 and the right punch 2, and then the height of the raw material at the upper part of the left punch is 10 ÷ 80% ~ 12.5cm, and the height of the raw material at the upper part of the right punch is 15 ÷ 80% ~ 18.75 cm; starting a press, driving the upper punch 4 to press downwards and continuously extrude powder in a pressing cavity by the briquetting 6 as shown in fig. 3, during the pressing, discharging air by an air cylinder of a pneumatic core rod (a floating punch) to enable the top rod 7 to descend to enable the horizontal height of the bottom of the left punch 1 to be consistent with that of the bottom of the right punch 2, even if the left punch 1 falls on the supporting table 5, after the pressing is finished, driving the upper punch 4 to move upwards by the briquetting 6 as shown in fig. 4 to obtain a compact 11 with a step end, wherein the low-order size of the compact 11 corresponding to the left punch 1 is 10cm, the high-order size of the compact 11 corresponding to the right punch 2 is 15cm, the height difference of the step of the compact 11 is the height difference between the tops of the left punch 1 and the right punch 2, namely, which is predetermined 5cm, after the compact is manufactured, the theoretical compression ratio of the raw material corresponding to the low-order segment pressed by the left punch 1 is 10 ÷ 12.5 × 100% ═ 80%, and the theoretical compression ratio of the raw material corresponding to the high-order segment pressed by the right punch 2 is 15.75 × 100% ÷ 80%, thereby making the seal of the compact uniform.

When the conventional die and method shown in fig. 5 and 6 are used for pressing, a step with a height difference of 5cm is punched downwards, when the material is charged, if the material is charged according to the height of 12.5cm of the upper layer material powder in the low stage, the height of the upper layer material powder in the high stage is 17.5cm, and after the material is made into a green compact, the theoretical compression ratio of the material corresponding to the low stage a of the green compact is 80% from 10 ÷ 12.5 × 100%, and the theoretical compression ratio of the material corresponding to the high stage B of the green compact is 86% from 15 ÷ 17.5 × 100%, so that the compression ratio of the material powder in the made green compact is inconsistent, the density of the green compact is not uniform, and the green compact is easy to deform during high-temperature sintering.

According to the die and the pressing method provided by the embodiment, the existing lower punch is separated into the left punch and the right punch with different heights, so that the raw material powder is compressed with the same compression ratio along with the relative movement of the female die and the upper punch, and the densities of all parts of the pressed blank tend to be consistent.

The above examples of the present invention are merely illustrative of the present invention and are not intended to limit the embodiments of the present invention. Variations and modifications in other variations will occur to those skilled in the art upon reading the foregoing description. Not all embodiments are exhaustive. All obvious changes and modifications of the present invention are within the scope of the present invention.

Claims

1. A method for manufacturing a pressed blank with a step by adopting a die comprises a lower punch, a female die and an upper punch, wherein the lower punch is formed by splicing a left punch and a right punch, the top of the left punch is higher than that of the right punch, and the pressed blank with the step also comprises a top rod arranged at the lower part of the left punch;

pressing by adopting a powder forming press, wherein a horizontal support table is arranged on the press, a vertical hole is formed in the support table, a jacking piece is arranged in the vertical hole, the jacking piece is a jacking rod arranged at the lower part of the left punch, and a pneumatic core rod cylinder arranged on the press is arranged at the lower part of the jacking rod; the upper portion of supporting bench sets up the briquetting that can be close to or keep away from perpendicularly for the supporting bench, its characterized in that includes the following step:

step 1, placing a left punch and a right punch on a supporting table of a press, wherein the left punch is positioned at the upper part of a vertical hole, a jacking piece drives the left punch to ascend to the position that the height difference between the top of the left punch and the top of the right punch is larger than the preset step height value of a pressed blank to be manufactured, sleeving a female die from the tops of the left punch and the right punch, controlling the height of the female die to ensure that the inner wall of a die hole of the female die and the tops of the left punch and the right punch form a pressing cavity with a stepped bottom surface, filling powder to be pressed into the pressing cavity, and installing the upper punch on a pressing block and being matched with the female die;