CN110541140A

CN110541140A - Mold nitriding process

Info

Publication number: CN110541140A
Application number: CN201910978920.3A
Authority: CN
Inventors: 杨如宏; 蒋佳丽; 吴露雷; 顾剑锋; 王博; 张幸; 杨旭东
Original assignee: Ikd Co Ltd; Shanghai Jiaotong University
Current assignee: Ikd Co Ltd; Shanghai Jiaotong University
Priority date: 2019-07-24
Filing date: 2019-10-15
Publication date: 2019-12-06
Anticipated expiration: 2039-10-15
Also published as: CN110423978A; CN110541140B

Abstract

The invention discloses a mold nitriding process, which comprises the following steps: the surface cleaning, the pre-oxidation and the controllable nitridation, the die and the die nitridation process, the controllable nitridation method of the invention can adjust the depth of a nitrided layer and improve the thermal fatigue performance of the die while improving the surface hardness, can improve the depth of a nitrided layer while ensuring the high hardness and the high thermal fatigue performance of a surface nitrided layer of the die, can effectively prevent the initiation and the expansion of thermal cracks, is different from the traditional nitridation process, provides a more convenient diffusion channel for the subsequent nitridation by the pre-oxidation, ensures the penetration of nitrogen atoms, and inhibits an Fe-N compound layer while improving the hardness.

Description

Mold nitriding process

Technical Field

The invention relates to the technical field of die-casting molds, in particular to a mold nitriding process.

Background

the die casting mold is an important hot work mold, and about 50% of aluminum alloy products all over the world are completed by a die casting process. In the process of producing aluminum alloy products by die casting, the aluminum alloy products are in a high-temperature and high-pressure environment for a long time, and when the aluminum alloy products are filled, the inner surface of a die expands due to rapid temperature rise to form compressive stress. In contrast, when the mold is opened and cooled by the coolant, the surface metal shrinks due to a rapid drop in temperature, resulting in tensile stress. The tensile stress and the compressive stress are repeatedly and alternately carried out, heat cracks, namely heat fatigue cracks, are formed after the tensile stress and the compressive stress exceed the strength of the material, the die fails after the heat fatigue cracks reach a certain degree, in addition, high-temperature molten metal can also cause the failures in the forms of abrasion, corrosion and the like on the surface of the die, the die needs to be polished and cleaned before the nitriding process, the die needs to be manually disassembled and cleaned after being polished usually, and the die has residues because the die cavity and other depressed areas exist in the center of the die and are directly cleaned on a polishing device, so that the processing efficiency is influenced. To this end, we propose a mold nitridation process.

Disclosure of Invention

The present invention is directed to a mold nitridation process to solve the problems of the background art.

In order to achieve the purpose, the invention provides the following technical scheme: a mold nitriding process comprises the following steps:

the method comprises the following steps: surface cleaning: and removing the oxide layer on the surface of the mold through equipment, and then cleaning.

step two: the pre-oxidation process comprises the following steps: the nitridation process is facilitated by heating the sample in air to form a thin oxide layer.

Step three: controllable nitridation: the formation of a white layer is inhibited by adjusting technological parameters such as temperature, ammonia decomposition rate, nitriding time and the like, the hardness of the surface layer is improved, and the depth of a nitriding layer is ensured.

The surface cleaning in the first step comprises the following steps:

a: the step comprises a grinding machine for grinding the workpiece to be ground, wherein a turnover plate is arranged on the grinding machine, and the grinding output end of the grinding machine grinds the workpiece to be ground on the turnover plate.

b: the step comprises a turnover plate, wherein a turnover device is arranged below the turnover plate, and the turnover plate can be adjusted at a certain angle through the turnover device.

c: the step comprises a fine adjustment device, wherein the fine adjustment device is arranged inside the turnover plate, and the turnover plate can be further subjected to angle fine adjustment through the fine adjustment device.

Preferably, the organic solvent is alcohol or acetone.

Preferably, in the second step, the pre-oxidation heating temperature is 400-500 ℃, and the heat preservation time is 2-4 hours.

Preferably, the nitriding temperature is controlled to be 500-600 ℃, the ammonia decomposition rate is 75-95%, and the nitriding time is 10-25 h.

Preferably, the depth of the penetrated layer is 100 μm under the condition, and the hardness is 900-1000 Hv.

Preferably, turning device includes first lead screw, the inside of polisher is seted up flutedly, bearing and recess inner wall connection are passed through at the both ends of first lead screw, just the arbitrary one end of first lead screw is run through the recess lateral wall and is connected with the motor, threaded connection has first thread bush on the first lead screw, just it has the jack-up pole to articulate on the outer wall of first thread bush, the other end of jack-up pole articulates there is little movable plate, little movable plate rotates to be connected on the returning face plate.

Preferably, micromatic setting includes the turning block, the one end and the fine motion plate of turning block are articulated, the other end both sides sliding connection of dwang has the slide rail, the slide rail is fixed with the inside of returning face plate, the dwang is close to that the one end of slide rail articulates there is electric telescopic handle.

Preferably, the fixed plate and the turnover plate are both provided with T-shaped grooves, and T-shaped blocks are connected in the T-shaped grooves in a sliding mode.

preferably, the T-shaped block comprises a second lead screw, two ends of the second lead screw are fixed inside the T-shaped block through bearings, one end of the second lead screw penetrates through the top of the T-shaped block, a second threaded sleeve is in threaded connection with the second lead screw, the outer wall of the second threaded sleeve is connected with a connecting block, the other end of the connecting block is connected with a limiting block, and the limiting block is in sliding connection with a sliding groove formed in one side wall of the T-shaped block.

preferably, one end of the second screw rod penetrating through the T-shaped block is connected with a polygonal block.

Compared with the prior art, the invention has the beneficial effects that:

1. According to the invention, the turnover plate for placing the grinding piece is turned over at a certain angle through the turning device, and after grinding is finished, the internal scraps can be easily discharged through the turning of the turnover plate, so that the turnover plate can be conveniently cleaned manually, and the whole processing efficiency is improved to a certain extent.

2. The controllable nitriding method provided by the invention can be used for regulating the depth of the nitriding layer and improving the thermal fatigue performance of the die while improving the surface hardness, and can be used for improving the depth of the nitriding layer while ensuring the high hardness and the high thermal fatigue performance of the surface nitriding layer of the die and effectively preventing the initiation and expansion of thermal cracks.

3. The method is different from the traditional nitriding process, and the preoxidation provides a more convenient diffusion channel for subsequent nitriding, so that nitrogen atoms are ensured to permeate, the hardness is improved, and the Fe-N compound layer is inhibited.

Drawings

FIG. 1 is a process flow diagram of the present invention;

FIG. 2 is an overall view of the polishing apparatus;

FIG. 3 is a half-sectional view of the polishing apparatus;

FIG. 4 is an enlarged view of area A in FIG. 3;

FIG. 5 is a structural view of a turnover plate of the polishing device;

FIG. 6 is an enlarged schematic view of region B in FIG. 5;

FIG. 7 is an overall view of a T-block;

FIG. 8 is a half-sectional view of a T-block;

FIG. 9 is a connection diagram of the flipping board and the inching board;

FIG. 10 is a half-sectional view of the flipping board and the inching board;

Fig. 11 is an enlarged view of the area C in fig. 10.

in the figure: 3-turning over the board; 4-a turning device; 5-T-shaped blocks; 6, a motor; 8-a groove; 9-a first threaded sleeve; 10-jacking up the rod; 11-T-shaped groove; 12-a second screw rod; 14-a second threaded sleeve; 15-connecting blocks; 16-a limiting block; 17-a chute; 18-polygonal blocks; 19-a travel switch; 21-a first lead screw; 22-a fine-tuning device; 23-a turning block; 24-an electric telescopic rod; 25-a microplate; 26-sliding rail.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1-11, the present invention provides a technical solution: a mold nitriding process comprises the following steps:

The surface cleaning in the first step comprises the following steps:

The organic solvent is alcohol or acetone, etc.

And step two, pre-oxidation heating temperature is 400-500 ℃, and heat preservation time is 2-4 h.

And step three, the nitriding temperature can be controlled to be 500-600 ℃, the ammonia decomposition rate is 75-95%, and the nitriding time is 10-25 h.

And step three, obtaining a penetrated layer with the depth of 100 mu m and the hardness of 900-1000 Hv.

The specific implementation mode is as follows: because the mold is oxidized in the air, a layer of oxide film of a metal compound exists on the surface of the mold, the oxide film on the surface of the hot work mold is removed through mechanical polishing, metal grinding can be generated during polishing, the surface of the mold is wiped through an organic solvent or a cleaning agent, impurities such as oil stains and metal dust caused by polishing are removed, the mold is rapidly put into a furnace for pre-oxidation heating after the removal of the oxide film and the surface impurities, the mold is prevented from being oxidized again by air when the mold is not put into the furnace for pre-oxidation, the mold is kept at the temperature of 400-500 ℃ for 2-4 h for heating for pre-oxidation, controllable nitridation is started after the heating for pre-oxidation, the set conditions of the controllable nitridation are that the reaction temperature is 500-600 ℃ and the ammonia decomposition rate is 75-95%, the mold lasts for 10-25 h under the conditions, the final depth of a permeated layer on the mold is 100 mu m, and the.

Main part and processing arm on the polisher are current polisher structure, and the fixed plate is fixed in the main part, and returning face plate 3 articulates at the middle part of fixed plate, and returning face plate 3's below is provided with turning device 4, can carry out the regulation of certain angle to returning face plate 3 through turning device 4, micromatic setting 22 sets up in returning face plate 3's inside, can carry out further angle fine setting to returning face plate 3 through micromatic setting 22.

Turning device includes first lead screw 21, recess 8 has been seted up to the inside of polisher, bearing and 8 interior wall connections of recess are passed through at the both ends of first lead screw 21, just arbitrary one end of first lead screw 21 runs through 8 lateral walls of recess and is connected with motor 6, threaded connection has first thread bush 9 on the first lead screw 21, just it has jack-up pole 10 to articulate on the outer wall of first thread bush 9, the other end of jack-up pole 10 articulates there is little movable plate 25, little movable plate 25 rotates to be connected on returning face plate 3

The specific implementation mode is as follows: turning device 4 jacks up returning face plate 3 from the bottom surface middle part of returning face plate 3, and returning face plate 3 rotates around its articulated department, thereby reach and become 90 degrees states with the fixed plate, turning device 4 is that the output shaft by motor 6 drives first lead screw 21 and rotates, because first thread bush 9 is with first lead screw 21 threaded connection, consequently first thread bush 9 moves to processing arm one side, processing arm motion makes jack-up pole 10 jack-up returning face plate 3, the lead screw has the self-locking function with the more firm and threaded connection of the connected transmission mode of thread bush, returning face plate 3 can automatic whereabouts and the accident appears when ejecting device 4 special cases appear.

The micromatic setting includes turning block 23, the one end and the fine motion board 25 of turning block 23 are articulated, the other end both sides sliding connection of dwang 23 has slide rail 26, the inside of slide rail 26 fixed with returning face plate 3, the one end that the dwang 23 is close to slide rail 26 articulates there is electric telescopic handle 24.

T-shaped grooves 11 are formed in the fixed plate 2 and the turnover plate 3, and T-shaped blocks 5 are connected in the T-shaped grooves 11 in a sliding mode.

T type piece 5 includes second lead screw 12, the inside of T type piece 5 is fixed in through the bearing in the both ends of second lead screw 12, just the top of T type piece 5 is run through to the one end of second lead screw 12, threaded connection has second thread bush 14 on the second lead screw 12, the outer wall connection of second thread bush 14 has connecting block 15, and connecting block 15's the other end is connected with stopper 16, just the spout 17 sliding connection that stopper 16 and T type piece 5 a lateral wall were seted up.

One end of the second screw rod 14 penetrating through the T-shaped block 5 is connected with a polygonal block 18.

the specific implementation mode is as follows: the fixing plate and the turning plate 3 are both provided with T-shaped grooves 11 in the transverse direction and the longitudinal direction, the T-shaped block 5 can slide in the T-shaped grooves to conveniently fix templates with different sizes, the fixing on the T-shaped block 5 can be adjusted, and the thickness of the template of each pair of molds is different, so the fixing height is also different, the existing fixing mode is to fix a block by a screw, a cushion block is added in the space between the block and the fixing plate 2, the operation is complicated, and a plurality of specifications of cushion blocks need to be manufactured, therefore, a second screw rod 12 and a second thread sleeve 14 are arranged in the T-shaped block 5 and are in threaded connection, the second thread sleeve 14 can move up and down on the second screw rod 12, the position can be adjusted by the positive and negative rotation of the second screw rod 14, the connecting block 15 is fixedly connected with the second thread sleeve 15, so the position can also change, and the limiting block 16 enables the connection with the connecting block 15 by the screw to be a round hole when the side holes, therefore, the limiting block 16 can be replaced by a round block to facilitate the fixing and protecting of the mold, because the ejecting device 4 can make the included angle between the turnover plate 3 and the fixed plate 2 be 90 degrees at most, at 90 degrees, the side surfaces of some grooves on the mold plate are also parallel to the fixed plate 2, or are not beneficial to the removal of some processing scraps, therefore, the fine adjustment device 22 can make the turnover plate 3 change the small angle again, when the ejecting device 4 ejects to the maximum angle of 90 degrees, the electric telescopic rod 24 works, the output end of the electric telescopic rod extends out and pushes one end of the rotating block 23, the changed end is connected with the sliding rail 26 in a sliding way, therefore, the electric telescopic rod can slide along the sliding rail 26, the other end of the rotating block 22 is hinged with the inching plate 25, when the rotating block 22 slides on the sliding rail 26, the distance between the turnover plate 3 and the inching plate 25 is gradually increased, but the other end of the rotating block is hinged with the other end of, because the groove on the template can be in a downward inclined state only by changing a small angle, a large-sized electric telescopic rod is not needed, and after the groove is in the downward inclined state, the cleaning liquid of the cleaning equipment on the equipment can be used to carry the waste scraps to automatically flow away from the template.

one end of the second screw rod 12 penetrates through the T-shaped block and is connected with a polygonal block 18, and the polygonal block 18 is convenient for rotating the second screw rod 12, so that the limit block 16 is convenient to fix and loosen.

The fixed plate is provided with a travel switch 19, when the turnover plate 3 is turned upwards, the processing arm can be collided, the template and the processing arm can be collided under the condition that an operator does not notice, the mold is damaged, and the use of the processing arm is influenced, so that the travel switch 19 can provide a signal when the turnover plate 3 leaves, and the controller controls the processing arm to turn to the side.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. A mold nitriding process is characterized in that: the method comprises the following steps:

the method comprises the following steps: surface cleaning: removing an oxide layer on the surface of the mold through equipment, and then cleaning;

Step two: the pre-oxidation process comprises the following steps: heating the sample in air to form a thin oxide layer and promote the nitridation process;

Step three: controllable nitridation: the formation of a white layer is inhibited by adjusting technological parameters such as temperature, ammonia decomposition rate, nitriding time and the like, the hardness of the surface layer is improved, and the depth of a nitriding layer is ensured;

the surface cleaning in the first step comprises the following steps:

a: the step comprises a grinding machine for grinding a to-be-ground part, wherein a turnover plate is arranged on the grinding machine, and a grinding output end of the grinding machine grinds the to-be-ground part on the turnover plate;

b: the step comprises a turnover plate, wherein a turnover device is arranged below the turnover plate, and the turnover plate can be adjusted at a certain angle through the turnover device;

2. the mold nitridation process of claim 1, wherein: the organic solvent is alcohol or acetone, etc.

3. the mold nitridation process of claim 1, wherein: and step two, pre-oxidation heating temperature is 400-500 ℃, and heat preservation time is 2-4 h.

4. The mold nitridation process of claim 1, wherein: and step three, the nitriding temperature can be controlled to be 500-600 ℃, the ammonia decomposition rate is 75-95%, and the nitriding time is 10-25 h.

5. The mold nitridation process of claim 4, wherein: under the condition, the depth of the obtained penetration layer is 100 mu m, and the hardness is 900-1000 Hv.

6. the mold nitridation process of claim 1, wherein: turning device includes first lead screw (21), recess (8) are seted up to the inside of polisher, bearing and recess (8) inner wall connection are passed through at the both ends of first lead screw (21), just arbitrary one end of first lead screw (21) runs through recess (8) lateral wall and is connected with motor (6), threaded connection has first thread bush (9) on first lead screw (21), just it has jack-up pole (10) to articulate on the outer wall of first thread bush (9), the other end of jack-up pole (10) articulates has fine movable plate (25), fine movable plate (25) rotate to be connected on returning face plate (3).

7. the mold nitridation process of claim 1, wherein: the fine setting device includes turning block (23), the one end and little movable plate (25) of turning block (23) are articulated, the other end both sides sliding connection of dwang (23) has slide rail (26), the inside of slide rail (26) fixed and returning face plate (3), the one end that dwang (23) is close to slide rail (26) articulates there is electric telescopic handle (24).

8. The mold nitridation process of claim 7, wherein: t-shaped grooves (11) are formed in the fixed plate (2) and the turnover plate (3), and T-shaped blocks (5) are connected in the T-shaped grooves (11) in a sliding mode.

9. The mold nitridation process of claim 8, wherein: t type piece (5) include second lead screw (12), the both ends of second lead screw (12) are fixed in the inside of T type piece (5) through the bearing, just the top of T type piece (5) is run through to the one end of second lead screw (12), threaded connection has second thread bush (14) on second lead screw (12), the outer wall connection of second thread bush (14) has connecting block (15), and stopper (16) are connected to the other end of connecting block (15), just spout (17) sliding connection that stopper (16) and T type piece (5) lateral wall were seted up.

10. The mold nitridation process of claim 9, wherein: one end of the second screw rod (14) penetrating through the T-shaped block (5) is connected with a polygonal block (18).