阅读说明：本技术 一种井式炉球化退火防脱碳方法及砂光装置 (Decarburization preventing method for spheroidizing annealing of pit furnace and sanding device ) 是由 白新歌 刘勇 迟旭 于 2021-07-02 设计创作，主要内容包括：本发明提供一种井式炉球化退火防脱碳方法,包括以下步骤：S1：线材输送至砂光机构去除表面原有脱碳层；S2：将上述S1得到的线材收线并装入井式炉进行球化退火；球化退火制度为随炉升温至770℃-805℃保温120-360分钟,本发明还提供了一种砂光装置,包括砂光机、用于向砂光机内输送线材的放线机构。本发明中通过砂光处理掉原线材表面的脱碳层,保证该砂光后线材经井式炉球化退火后表面基本无脱碳或脱碳在合理范围内,获得原有脱碳层不加剧不加深的效果,达到改善线材表面质量,使心、表硬度极差减少,以保证拉拔时金属表面和心部同步变形,不易与模具粘连,提高成材率；并且淬回火后,心、表硬度极差变小,绕簧或者绕环时能同步变形。(The invention provides a decarburization preventing method for spheroidizing annealing of a pit furnace, which comprises the following steps: s1: conveying the wire to a sanding mechanism to remove the original decarburized layer on the surface; s2: taking up the wire obtained in the step S1, and loading the wire into a pit furnace for spheroidizing annealing; the spheroidizing annealing system is that the temperature is increased to 770-805 ℃ along with the furnace and is kept for 120-360 minutes, the invention also provides a sanding device, which comprises a sanding machine and a paying-off mechanism used for conveying wires into the sanding machine. According to the invention, the decarburized layer on the surface of the original wire rod is removed by sanding, so that the surface of the sanded wire rod is basically free of decarburization or the decarburization is in a reasonable range after spheroidizing annealing in a pit furnace, the effect that the original decarburized layer is not aggravated or deepened is obtained, the surface quality of the wire rod is improved, the extreme difference between the core hardness and the surface hardness is reduced, the synchronous deformation of the metal surface and the core during drawing is ensured, the wire rod is not easy to adhere to a die, and the yield is improved; after quenching and tempering, the hardness difference of the core and the surface is reduced, and the spring or the ring can be synchronously deformed during winding.)

1. A decarburization method for spheroidizing annealing of a pit furnace is characterized by comprising the following steps:

s1: conveying the wire to a sanding mechanism to remove the original decarburized layer on the surface;

s2: taking up the wire obtained in the step S1, and loading the wire into a pit furnace for spheroidizing annealing; the spheroidizing annealing system is that the temperature is increased to 770-805 ℃ along with the furnace and is preserved for 120-minus-one times for 360 minutes, then the temperature is reduced to 680-720 ℃ and is preserved for 120-minus-one times for 240 minutes, then the temperature is continuously reduced to 580-620 ℃ and is preserved for 60-120 minutes, the temperature is reduced to below 500 ℃, and then the furnace is taken out for air cooling.

2. The decarburization method of claim 1, wherein in step S1, the wire is conveyed to the sanding mechanism by a wire unwinding device; in step S2, the wire is stored by the wire winding device.

3. The decarburization method according to claim 1 or 2, wherein the sanding mechanism is a sander.

4. The method for decarbonization prevention according to claim 3, wherein the wire rod is subjected to spheroidizing annealing in step S2 and then subjected to secondary sanding treatment, and the method further comprises a step of coating the wire rod with an oil film after the secondary sanding treatment.

5. The anti-decarbonization method according to claim 3, wherein the temperature raising stage in the step S2 further comprises the step of heating to 680-720 ℃ for preheating for 60-90 minutes.

6. A sanding device used in the decarburization method as defined in any one of claims 4 to 5, comprising a sanding machine (10), a wire pay-off mechanism (20) for feeding the wire into the sanding machine, a film coating machine (30) for coating the secondary sanded wire output by the sanding machine with an oil film, and a wire take-up mechanism (40) for receiving the output wire of the film coating machine.

7. The sanding device according to claim 6, further comprising a bend descaling mechanism (50) comprising two rows of line roller sets arranged one above the other, wherein the wire rod is alternately wound around and extends to the inlet of the sanding machine along the line rollers (51) of the two rows of line roller sets.

Technical Field

The invention relates to the technical field of piston ring wire rod processing, in particular to a decarbonization preventing method and a sanding device for spheroidizing annealing of a pit furnace.

Background

With the national improvement of the emission requirements of automobiles, the manufacturing process of the piston ring is more and more complex, and the requirements on the surface quality of wire rods are higher and higher. In the production process of piston ring wire rods, in the process of pit furnace spheroidizing annealing heat treatment, carbon steel supplies in a hot rolling state, the surface of raw materials has oxide skin and decarburization, the wire rods are in the pit furnace annealing process, because the annealing temperature is more than 727 ℃, the temperature is the lowest point of the structure transformation of steel materials, the actual spheroidizing temperature is mostly higher than the temperature, the internal atom vibration and diffusion of the materials are intensified, and the heat preservation time is very long (90-240 minutes), so the decarburization level of the surface of the wire rods is greatly intensified, and the phenomenon of intensification of a transition layer can be generated. Namely, the raw material wire rod has a decarburized layer, and the surface layer decarburization is accelerated in the annealing process of the pit furnace, so that the diffusion layer is further diffused inwards, and the depth of the transition layer is increased. Although the prior art has a method for removing a decarburized layer on the surface of a wire rod by adopting an acid washing method, the method involves chemical reaction, the surface structure of the wire rod is affected, and the pickling solution is difficult to soak into the wire rod, so that the cleaned layer is shallow, a part of decarburized layer is remained, and a transition layer in the decarburized layer cannot be eliminated. In addition, even if the decarburized layer is cleaned by a sanding method after the spheroidizing annealing of the shaft furnace, the decarburized layer is deepened after the spheroidizing annealing and is uneven in layer depth, so that the decarburized layer is difficult to completely remove by a sanding method.

Disclosure of Invention

The invention provides a decarburization method for sanding a wire rod and then carrying out pit furnace spheroidizing annealing, which can ensure that the original decarburization layer is not intensified or deepened and achieve the effect of improving the surface quality of the wire rod.

In order to solve the technical problems, the invention adopts the following technical scheme:

a decarburization preventing method for spheroidizing annealing of a pit furnace comprises the following steps:

s1: conveying the wire to a sanding mechanism to remove the original decarburized layer on the surface;

s2: taking up the wire obtained in the step S1, and loading the wire into a pit furnace for spheroidizing annealing; the spheroidizing annealing system is that the temperature is increased to 770-805 ℃ along with the furnace and is preserved for 120-minus-one times for 360 minutes, then the temperature is reduced to 680-720 ℃ and is preserved for 120-minus-one times for 240 minutes, then the temperature is continuously reduced to 580-620 ℃ and is preserved for 60-120 minutes, the temperature is reduced to below 500 ℃, and then the furnace is taken out for air cooling.

The sanding device used by the anti-decarbonization method comprises a sanding machine, a pay-off mechanism used for conveying wires into the sanding machine, a coating machine used for coating an oil film on the secondary sanding wires output by the sanding machine, and a take-up mechanism used for accommodating the wires output by the coating machine.

According to the technical scheme, the invention has the following beneficial effects: according to the invention, the decarburized layer on the surface of the original wire rod is removed by sanding, so that the surface of the sanded wire rod is basically free of decarburization or the decarburization is in a reasonable range after spheroidizing annealing in a pit furnace, the effect that the original decarburized layer is not aggravated or deepened is obtained, the surface quality of the wire rod is improved, the extreme difference between the core hardness and the surface hardness is reduced, the synchronous deformation of the metal surface and the core during drawing is ensured, the wire rod is not easy to adhere to a die, and the yield is improved; after quenching and tempering, the hardness difference of the core and the surface is reduced, and the spring or the ring can be synchronously deformed during winding.

Drawings

FIG. 1 is a flow chart of the decarbonization preventing method of the present invention;

FIG. 2 is a schematic view of a sample binding position;

FIG. 3 is a schematic structural view of the sanding device;

FIG. 4 is a diagram of a pit furnace spheroidizing annealing process.

In the figure: 10. a sanding machine; 20. a pay-off mechanism; 30. coating a film machine; 40. a take-up mechanism; 50. bending the descaling mechanism; 51. and (4) wire roller.

Detailed Description

A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

Example (b):

referring to fig. 1 and 4, the decarburization preventing method for spheroidizing annealing of the shaft furnace comprises the following steps:

s1: conveying the wire to a sanding mechanism to remove the original decarburized layer on the surface;

s2: taking up the wire obtained in the step S1, and loading the wire into a pit furnace for spheroidizing annealing; the spheroidizing annealing system is that the temperature is increased to 770-805 ℃ along with the furnace and is kept for 120-plus-material 360 minutes, then the temperature is reduced to 680-720 ℃ and is kept for 120-plus-material 240 minutes, then the temperature is continuously reduced to 580-620 ℃ and is kept for 60-120 minutes, the temperature is reduced to below 500 ℃, and then the wire is taken out of the furnace for air cooling; on the other hand, the material structure and the components can be uniform, the material performance can be improved or the structure preparation can be made for the later heat treatment; in addition, the hardness of the wire rod can be reduced, and the subsequent cold processing such as drawing and rolling can be conveniently carried out.

As a preferred technical solution of the present invention, in order to facilitate conveying the wire rod into the sanding mechanism for decarburized layer removal, a pay-off device is further provided in step S1 to convey the wire rod; correspondingly, in order to facilitate conveying the sanded wire rods out of the sanding mechanism, the wire rods can be stored by the take-up device arranged at the output end of the sanding mechanism.

Further, the sanding mechanism is a sander.

As a preferable technical solution of the present invention, the step of coating an oil film on the wire after the wire is sanded in the step S1 is further included, so that a protective oil film can be coated on the sanded wire, thereby protecting the wire.

As a preferable technical scheme of the invention, the temperature raising stage in the step S2 further comprises the step of heating to 680-720 ℃ for preheating for 60-90 minutes, and the preheating step can prevent the wire from being overheated excessively during heating, so that the internal structure of the wire is prevented from being adversely affected.

Referring to fig. 3, the invention also provides a sanding device, which comprises a sanding machine 10, a pay-off mechanism 20 for conveying wires into the sanding machine, a film coating machine 30 for coating an oil film on the secondarily sanded wires output by the sanding machine, and a take-up mechanism 40 for accommodating the wires output by the film coating machine, so that the wires are conveyed into the sanding mechanism through the pay-off mechanism for sanding and are accommodated by the take-up mechanism, and the sanded wires are conveniently put into a well type furnace for spheroidizing annealing.

In addition, after the spheroidizing annealing treatment of the shaft furnace, the wire rod can be subjected to secondary sanding treatment to fully remove the decarburized layer, and the wire rod subjected to secondary sanding is coated with an oil film through a film coating machine.

Further, in order to achieve better descaling of the wire rod, a bending descaling mechanism 50 is further arranged at the sanding input end and comprises a box body and two line roller sets which are arranged up and down and arranged inside the box body, wherein the wire rod is wound and connected alternately along the line rollers 51 in the upper and lower line roller sets and finally enters the sanding machine through the inlet of the sanding machine to be sanded.

In order to verify the feasibility of this well-type furnace spheroidizing annealing decarburization method, set up two sets of contrast tests, the experiment group adopts sand light appearance-spheroidizing annealing to handle, contrast group adopts not sand light appearance-spheroidizing annealing to handle, bind above-mentioned two sets of experiment back samples as figure 2 on raw and other materials, the form that the sample divide into five layers of setting of upper strata, well upper strata, middle level, well lower floor, lower floor is fixed on raw and other materials promptly, measure the decarbonization value of five layers of wire rod in above-mentioned experiment group and contrast group respectively, the measurement mode is: and selecting four sampling points on each layer, measuring the decarburization values of the four sampling points, and calculating the average value of the four sampling points as the decarburization value of the wire rod on the layer. The method for measuring the decarburization value adopts a metallographic method, namely, the structural change of a sample from the surface to a matrix along with the change of the carbon content is observed under an optical microscope, and the depth of a decarburization layer is the sum of a complete decarburization layer and a partial decarburization layer, and the unit is mum. The following tables were obtained:

TABLE 1 decarbonization values of the individual layers of the experimental groups

	Before annealing	After annealing	Before annealing	After annealing	Before annealing	After annealing	Before annealing	After annealing
									Upper layer of	26.88	48.45	37.23	46.22	33.73	45.74	44.76	47.97
Middle and upper layer	0	40.07	23.03	51.59	42.66	76.48	53.11	66.11
									Middle layer	60.04	41.33	49.96	72.85	0	23.89	43.27	36.81
Middle and lower layer	34	74.56	0	53.87	43.78	87.48	0	63.47
									Lower layer	23	35.66	8.02	30.29	0	64.6	15.86	54.9

TABLE 2 decarbonization values for the individual layers of the comparison set

As can be seen from the two groups of comparative experiments, the decarburized layer depth of the non-sanded sample is obviously increased after spheroidizing annealing; the depth of the decarburized layer of the sanded sample is very small after spheroidizing annealing, and the decarburized layer on the surface of the wire rod can be effectively removed through secondary sanding. The decarburization mechanism is as follows: the method comprises the following steps: 2Fe₃C+O₂＝6Fe+2CO；②：Fe₃C+2H₂＝3Fe+CH₄；③：Fe₃C+H₂O＝3Fe+CO+H₂；④：Fe₃C+CO₂3Fe +2 CO. Since the degree of decarburization increases under an oxidizing atmosphere containing water, carbon dioxide, etc., particularly under a condition of containing much oxygen, oxygen in the scale and hydrogen (Fe) are mixed in an environment where ammonia decomposition gas is used as a protective atmosphere₃O₄+4H₂＝3Fe+4H₂O) interaction to generate water, wherein the water is changed into water vapor when the temperature in the furnace exceeds 100 ℃, the reaction is accelerated along with the gradual rise of the temperature in the furnace, when the temperature exceeds 727 ℃, the atom vibration in the material is greatly intensified, the concentration of the water vapor is sharply increased, and the atom vibration and the diffusion are intensified, meanwhile, because the heat preservation time is very long (120 plus 360 minutes), a hydrous oxidizing condition is created for decarburization, the diffusion of the decarburization layer depth and the transition layer is greatly accelerated, so that the problem of deepening of a decarburized layer can be caused after a non-sanded sample is spheroidized and annealed, the oxide skin on the surface of the sample is removed after the sample is sanded, the hydrous oxidizing atmosphere in the furnace is reduced, and the original decarbed layer is not intensified and is not deepened.

The above-mentioned embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements made to the technical solution of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.