JPS5930784B2 - roller chain pin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a roller chain pin that has excellent wear resistance when used for power transmission.

In recent years, the usage conditions for roller chains and bushed chains (hereinafter referred to as chains) for power transmission have become increasingly harsh, especially for equipment that requires complicated starting, stopping, forward/reverse, acceleration/deceleration, etc. The chain tension generated by an impact (hereinafter referred to as impact force) is very large, which often causes the chain to break after a short period of use.

In such cases, in conventional chains, the pins often break due to bending or shearing, which is completely different from the conventional fracture in which the link plate fatigues and breaks after being used for a long time without being subjected to impact force. The situation is different. Since the pin of the chain constitutes the bearing part along with the bushing, it is necessary to increase the surface hardness in order to obtain wear resistance, and for this reason, conventionally, carburized low carbon alloy case hardened steel has been used.

Its composition is approximately C < 0.23%, and other alloying elements such as Cr, Ni, Mo, and Mn are included. Pins made of these low carbon alloy case hardened steels have a hard surface but a tough interior. Although it has a certain degree of resistance against impact forces, it is still insufficient to withstand impact forces at present. This is due to the lack of strength in the core of the pin, so one possible solution to this problem is the use of medium-high carbon strength steel, but carburizing is used to add wear resistance to commercially available materials of this type. When nitriding, the breaking load of the chain is much lower than that of chains made of case-hardened alloy steel. One of the reasons for this is that when case-hardened alloy steel is carburized, the degree of hardening differs due to the difference in carbon concentration between the surface and the core, which causes compressive residual stress to occur on the surface and weaken the brittle surface layer. On the other hand, when carburized medium-high carbon steel is used, there is no significant difference in the hardening of the surface and core, and there is no compressive residual stress, so the bending action prevents the surface layer from forming. Cracks occur,
It is believed that this crack immediately propagates to the core. Therefore, for the reasons mentioned above, pins made of strong steel are used in order to obtain strength that can withstand large impacts, but the conventional approach when using these pins has been to ignore wear resistance. Therefore, the present invention aims to eliminate the above-mentioned drawbacks and provide a roller chain pin that is made of medium-carbon strong steel and is carbonitrided, then quenched and tempered, so that the impact strength does not decrease even if the material is carburized. and
Weight ratio: C0.35-0.45%, 5i0.15-0.
50%, Mn0, 35-0.60%, Po, Os% or less, 50.03% or less, Ni3.0-4.0%, Cr1.
0 to 1.5 (: F6 is the main component, WO.3 to 1.0%
and V.O. The steel material has a composition of 3-0.6% TiO, 2-0.6% TiO, and 2-0.6%, with the remainder consisting of Fe and impurities.The surface of the steel material has a carbonitrided layer, and the core has a marten layer. The feature is that each site is formed individually. First of all, the main composition of the pin material according to this invention is CO. 35-0.45%, SiO. l5
~0.50%, MnO. 35-0.60%, PO, O3
% or less, SO, O3% or less, Ni3. O~4.0%,C
rl. In addition to O~1.5% of various elements, WO. 3-1.0%
and VO. 3-0.6% TiO. It contains 2 to 0.6% of one or two kinds, with the remainder consisting of Fe and impurities.

Among these, C is a fundamentally important element to provide strength to the core of the pin after heat treatment, and if it is 0.35% or less, there is no difference in performance compared to low carbon case hardening steel, and if it is 0.35% or less, there is no difference in performance compared to low carbon case hardened steel. If it exceeds 45%, the effect of weakening will be greater and it will not be suitable as a pin material for wear-resistant roller chains.
After all, C is optimally 0.35 to 0.45 f). Sl,
Mn is an element that sufficiently deoxidizes steel materials and improves hardenability.If the content is too high, quenching embrittlement occurs, so if Sl is 0.15-0.501)
, Mn is suitably 0.35 to 0.60%.

In addition, if P and S contain more than 0.03%, the steel will become brittle and become unsuitable as a pin material.
．． 03% or less, and 3.0 to 4.0% Ni, C
By simultaneously containing 1.0 to 1.5% r, Ni, Cr
It significantly increases the hardenability of the steel, increases the hardening depth, and reduces the mass effect of the steel, while increasing the surface hardness and strength, and Increases toughness. In addition, the reason why the Ni content is 3.0 to 4.0%, higher than that of ordinary steel materials, is to suppress the growth of austenite grains that occur during carburizing heating, increase toughness after quenching, and reduce the Cr content. This is to alleviate the accompanying decrease in toughness. However, although it is necessary to contain Cr together with Nl for the reasons mentioned above, if the Cr content exceeds 1.5%, excessive carburization will occur, forming noticeable steel-like cementite at grain boundaries, resulting in a carburized layer. Cr is 1.0 to 1.5 because it embrittles
(:Ft) is appropriate and necessary. Furthermore, with the amount of C in this invention, it is not possible to expect the effect of compressive residual stress on the surface during carburizing and quenching, and unless the toughness of the carburized layer is particularly increased, it will not be suitable as a pin material for a roller chain with high wear resistance. This is because. W, V, and Tl all combine with C to form carbides, increasing wear resistance and tempering resistance, but on the other hand, C in the base metal decreases.
As a result, the hardenability decreases, so WO. 3-1.0%,
VO. 3-0.6%, TiO. 2 to 0.6% is appropriate. By carbonitriding, V and Ti produce extremely hard particles of VN and TlN, further improving wear resistance. Furthermore, W, V and Ti are effective in increasing resistance to temper softening, and are effective for improving roller chain Helps prevent strength loss due to temperature rise during use. This invention has been described above mainly with the aim of preventing a decrease in toughness due to carburization of the pin material of a roller chain, but on the other hand, it has been found that the impact load acting on the chain is alleviated when the elastic elongation of the chain is large. Therefore, C, Cr, W, V, Ti is used as the pin material of the roller chain according to the present invention.
This has the function of increasing the elastic limit of the pin, and provides excellent performance as a wear-resistant roller chain.

Next, examples of the present invention will be given to explain its effects.

The chemical analysis results are CO. by weight. 42(Ff), SiO,
22%, MnO. 4O(f), PO. Ol8(!),S
O. O23%, Ni3.33%, Crl. 30%, WO
．． A steel material consisting of 33%, VO, and 36% Fe and impurities was used as the pin material for a JIS5O roller chain, and after forming it into a diameter of 5.08 mm and a length of 220 Ttm, it was carbonitrided with gas at 850°C. 30 at
The material is heated for 1 minute to form a carbonitrided layer of about 0.2 mm on the surface, immediately quenched in oil, and then tempered at a low temperature to form pins for roller chains.

The surface hardness of this pin is Bitkers hardness Hv (200g)
The core hardness is 730 to 780, and the hardness is Vickers hardness Hv (20
0g) is 540-600. In addition, in this invention, the chemical analysis results are CO. 42%, SiO. 22
%, MnO, 4%, PO. Ol8%, SO. O23%,
Ni3.33%, Crl. 30%, WO. 33%, Ti
O, 35 (Ff) steel material other than Fe and impurities was adopted as the pin material of the JIS 5OO roller chain, and after forming this pin material into a diameter of 5.08 m11 and a length of 20 mm in the same way as in the previous case, Approximately 0.2
When a carbonitrided layer of mm thick is formed on the surface, immediately quenched in oil, and then tempered at a low temperature (180°C), a roller chain pin with a martensite structure formed in the core is obtained. , so the Vickers hardness Hv = 1750 at the surface under a load of 200g, and the load at the core is 200g.
The hardness of the pin is H = 550, Ti combines with C to form TiC, and the surface is carbonitrided to produce extremely hard TiN particles, making it even more wear resistant than conventional pins. You can get pins that are rich in sex.

Furthermore, in this invention, the chemical analysis results indicate that CO
．． 42f), SiO. 22(f), MnO, 4%, PO
．． Ol8%, SO. O23%, Ni3.33%, Crl
．． 30%, WO. 33%, VO. 32(11), TiO
．． 36% Others are steel materials consisting of Fe and impurities, J
This pin material was used as a pin material for an IS5O roller chain, and this pin material was formed into a diameter of 5.08 mm and a length of 20 mm in the same manner as described above, and then heated by gas carbonitriding at 850° C. for 30 minutes to a diameter of 0.2 mm. When a carbonitrided layer is formed on the surface, immediately sintered in oil, and then tempered at a low temperature (180°C), a roller chain pin with a martensite structure formed in the core is obtained. At the surface, under a load of 200g, the Vickers hardness Hv = 770
, At the core, under a load of 200g, the Bitkers hardness Hv=
580, and due to the coexistence with V(5Ti), a carbonitrided layer with extremely hard VN and TiN particles is formed on the surface, and the wear resistance of the pin is higher than that of conventional pins. It will be further improved.

Next, in a testing apparatus as shown in FIG. 1, the pins made of the medium-carbon strong steel according to the present invention and the SNCM2 and low-carbon case-hardened steel described in the conventional example were assembled into roller chains of the same size, and a series of long The test was conducted with 19 links.

Therefore, the (1) components (grounding conditions, depth and surface of the surface layer,
Hardness of each core (Bitzkers hardness HVl load 200g)
If you display it, it will look like this: Next, the outline of this test device will be described with reference to FIG. 1. A pulley 3 is rotatably supported on a support shaft 2 that is mounted on a support piece 1 that can be fixed and suspended from the ceiling.
An inverted U-shaped frame body 5 is attached to one end of the rope 4 that is hung on the pulley 3.
While the center of the rope 4 is suspended, the other end of the rope 4 is wound around a drum (not shown), and the upper end of the roller chain Y consisting of the 19 links is fixed to the center of the lower surface of the horizontal part 5h of the frame 5, and the lower end Even if a 22Kf weight W is suspended and the lower end of the frame 5 falls from a height H to the floor G, the lower end of the weight W will not come into contact with the floor G, and the frame 5 will remain on the floor. Roller chain Y absorbs the impact energy of weight W when it comes into contact with surface G.
The frame body 5 is suspended and supported by the rope 4 at the position shown in the figure, and the frame body 5 is suspended and supported by the rope 4 at the position shown in the figure.
Figure 2 shows the results of dropping the roller chain Y onto the floor G and measuring the number N of repeated drops until the roller chain Y breaks due to the impact of the fall.

That is, in FIG. 2, the height H (unit: Cm) from the floor surface G at the lower end of the frame 5 is plotted on the vertical axis, and the logarithm of the number of repeated falls N is plotted on the horizontal axis. A roller chain with built-in pins Ya, a roller chain with built-in pins made from conventional SNCM2 called Ybl, and a roller chain with built-in pins made of the same low carbon case-hardened steel as Yc.
However, as is clear from this Figure 2,
For example, when the frame 5 is dropped from a height of 70 degrees,
It is understood that type b breaks after 3 to 4 times, while type Ya starts to break after being dropped 40 times or more, and conversely, type Yc breaks after 40 repeated drops. The height is 31~35cm, and the height of Yb is 47~52cm. It is understood that Ya will break when dropped from a height of about 70 to 74 cm, whereas Ya will break when dropped from a height of about 70 to 74 cm. Accordingly, Ya has extremely excellent impact resistance. It is easily understood that this method has a significant effect.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a testing device for impact resistance of roller chains, and Fig. 2 is a logarithmic graph showing impact resistance test results according to a conventional example and an example according to the present invention when using the testing device shown in Fig. 1. It is.

Claims (1)

[Claims] 1 C0.35-0.45%, Si0.15-0.15% by weight
0.5%, Mn 0.35-0.60%, P 0.03% or less, S 0.03% or less, Ni 3.0-4.0%, Cr1
．． The main component is 0 to 1.5%, and one or two of W0.3 to 1.0%, V0.0.3 to 0.6%, and Ti0.2 to 0.6%, and the remainder is A pin for a roller chain, characterized in that a carbonitrided layer is formed on the surface of a steel material having a composition consisting of Fe and impurities, and martensite is formed in the core.