JP2006089023A - Link and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a link capable of reducing a step caused by the wear on a tread of the link, and its manufacturing method. <P>SOLUTION: The link has linkage ports 15, 16 on both ends thereof, and has a tread 13 which is arranged to connect an upper portion of one linkage port 15 to an upper portion of the other linkage port. Parts in a vicinity of both ends of the tread 13 are formed low in hardness compared with a part in the center of the tread. The parts located in a vicinity of both ends of the tread can be easily worn compared with the part located in the center. Since the easily worn parts in a vicinity of both ends are closer to the linkage ports, the wear during the use is smaller than that of the part located in the center of the tread. Thus, the step generated in the tread can be reduced from the difference in the wear during the use. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a link constituting a crawler belt in a tracked work machine and a method for manufacturing the link, and more particularly to a link capable of reducing a step due to wear on a tread surface of the link and a method for manufacturing the link.

FIG. 5 is a block diagram showing a traveling device having a conventional link.
A pair of left and right traveling devices 10 as shown in FIG. The traveling device 10 has a crawler belt 1. The crawler belt 1 is configured by connecting the links 3 to which the crawler plate 2 is fastened with bolts in an annular manner by connecting pins 4.

  The traveling device 10 includes a track frame 5 disposed along the vehicle front-rear direction, and an idler 6 and a sprocket 7 that are rotatably attached to both front-rear ends of the track frame 5. Further, between the idler 6 and the sprocket 7, three sets of lower rolling wheels having a pair of lower and lower rolling wheels 8, 8 supported at the lower part of the track frame 5 so as to be swingable up and down and rotatably. A device 9a and a lower roller device 9b having one lower roller 8 supported so as to be swingable up and down and rotatable are provided. The lower roller 8 of each of the lower roller devices 9a and 9b rolls in contact with the tread surface of the crawler belt link (see Patent Document 1).

6 is a partially exploded perspective view of the crawler belt shown in FIG.
The crawler belt 1 includes a crawler plate 2, a link 3, a bush 11, a connecting pin 4, and a dust seal 12. As shown in FIG. 6, a bush 11 is strongly pressed into the link 3 and the connecting pin 4 is loosely fitted in the bush. The connecting pin 4 is strongly press-fitted and connected to the link 3b located outside the link 3, and the crawler belt 1 is bent between the bush 11 and the connecting pin 4 (see Non-Patent Document 1).

FIG. 7A is a plan view showing the tread surface of the link shown in FIG. 6, and FIG. 7B is a view of the link provided with the tread surface shown in FIG.
As shown in FIG. 7B, the link 3 is formed with a tread surface 13 that makes rolling contact with a lower rolling wheel (indicated by reference numeral 8 in FIG. 5) while supporting the weight of the vehicle body on the upper surface. The tread 13 is also an idler tread. A shoe attachment surface 14 for attaching the crawler plate 2 is formed on the opposite side of the tread surface 13. In addition, a bush hole (link connection port) 15 into which the bush 11 is inserted is formed at one end of the link 3, and a pin hole (link connection port) 16 into which the connection pin 4 is inserted into the other end of the link. A seal counterbore (not shown) for fitting the dust seal 12 is formed concentrically. Further, the link 3 is formed with shoe bolt holes (not shown) through which the mounting bolts of the shoe plate 2 are inserted, shoe nut seating surfaces 17 and 17 on which the mounting nuts of the shoe plate 2 are seated. A space indicated by reference numeral 18 is a window portion for receiving a mounting nut (see Patent Document 2).

JP 2002-362441 A (22nd to 27th paragraphs, FIG. 1) Japanese Patent Laying-Open No. 2004-17782 (15th paragraph, FIG. 2) Practical machinery series Bulldozer Publisher; Publishing of industrial books 1969, Author; Tomoyoshi Morita (70 pages)

  By the way, when driving the vehicle body as described above, the vehicle body may vibrate. One of the causes of the vehicle body vibration is a step generated on the tread 13 when the tread 13 of the link 3 is worn. The wear on the tread surface of the link occurs when the link and the wheel such as the lower roller contact with each other and the idler come into contact with each other when the crawler belt is driven. In the conventional link, the tread surface has a uniform hardness over the entire surface, the tread width is large and there is a difference in surface pressure, and the tread surface of the link and the wheel or idler have a portion that does not come into contact with the structural contact portion. For this reason, a level difference occurs on the tread surface of the link as wear progresses. In addition, the site | part which does not contact on structure is the tread surface of the link of the link pin 4 upper position. This is because when the link is wound around the idler, the link pin 4 is bent around the center and the crawler belt chain forms a polygon so as to contact the idler. This is because only the tread is in contact with the idler and the tread surface above the link pin 4 is not in contact with the idler. Also, when the link comes into contact with the wheel, the tread surface of the link above the link pin 4 and the wheel are difficult to contact for the same reason. The part where the wheel contacts structurally is different from the part where the idler contacts structurally. The outer diameter of the wheel is smaller than that of the idler, and usually only two links 3 connected by one link pin 4 are in contact with the wheel. The contact position on the tread is the contact between the idler and the tread. While the position is near the center of the tread, it is always above the position above the link pin 4. In the case of a crawler belt wound in an elliptical shape, the wear on the tread due to contact with the idler is less than the wear on the tread caused by contact with the wheel.

A step on the tread surface of the link will be described.
As shown in FIGS. 7A and 7B, the portions 19 and 19 located above the link connection ports 15 and 16 on the tread surface 13 of the link are positions where the idler and the wheel do not come in contact with each other. The amount of wear is less than that of the portion located at the center of the tread surface 13. Accordingly, convex portions are generated in the portions 19 and 19 located above the link connection port. This convex shape has a height of, for example, about 4 mm with respect to the portion located at the center of the tread. Further, the portion 20 located above the one link connecting port (bush hole) 15 and on the center side of the tread has a smaller tread width than the portion located at the center of the tread as shown in FIG. Therefore, the amount of wear is large. Therefore, a depression (concave portion) is generated in the portion 20. This dent is about 4 mm deep with respect to the part located in the center of the tread.

  When the step amount of the link tread increases, the vehicle body vibration increases. Therefore, it is necessary to perform maintenance so that the tread of the link becomes flat so that the tread becomes flat. In addition, after a plurality of maintenance operations, the wear life is reached, so it is necessary to replace the link. Therefore, it is required to reduce the maintenance cost and extend the wear life by reducing the amount of the step generated on the tread surface of the link.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a link that can reduce a step due to wear on the tread surface of the link and a method for manufacturing the link.

In order to solve the above problems, the link according to the present invention is a link having a tread surface.
A portion of the tread that has a small amount of wear during use is formed with a lower hardness than a portion of the tread that has a large amount of wear during use.

  According to the link according to the present invention, it is possible to make the portion of the tread surface with a small amount of wear during use easier to wear than the portion with a large amount of wear during use. For this reason, the level | step difference by abrasion can be reduced in the tread surface of a link.

The link according to the present invention has a link connecting port at both ends, and a link having a tread arranged so as to connect the upper side of one link connecting port and the upper side of the other link connecting port,
A portion near both ends of the tread has a lower hardness than a central portion of the tread.

  According to the link according to the present invention, a portion located near both ends of the tread can be more easily worn than a portion located in the center. Since the portions near both ends that are easily worn like this are close to the link connection port, the amount of wear during use is less than the portion located in the center of the tread on the structure. Therefore, the level | step difference which arises on a tread from the difference in the amount of wear at the time of use can be reduced.

The link manufacturing method according to the present invention is a method of manufacturing a link having a link connecting port at both ends and having a tread arranged so as to connect the upper side of one link connecting port and the upper side of the other link connecting port.
Tempering is carried out at a temperature near the both ends of the tread surface at a temperature higher than that of the central portion of the tread surface.

According to the link manufacturing method of the present invention described above, by performing tempering at a higher temperature in the vicinity of both ends of the tread surface than in the center, the hardness in the vicinity of both ends can be reduced to the central portion. Compared to, it can be formed low. Therefore, the level | step difference which arises on a tread from the difference in the amount of wear at the time of use can be reduced.
The present disclosure includes the embodiments, figures, and claims disclosed in Japanese Patent Application 2004-247765 filed on August 27, 2004 as it is.

  As described above, according to the present invention, it is possible to provide a link that can reduce a step due to wear on the tread surface of the link and a method for manufacturing the link.

BEST MODE FOR CARRYING OUT THE INVENTION

  FIG. 1A is a diagram showing a hardness distribution of a tread surface of a link according to an embodiment of the present invention, and FIG. 1B is a link provided with a tread surface having the hardness distribution shown in FIG. FIG. In the link according to the present embodiment, the same parts as those of the conventional link are denoted by the same reference numerals, and the description of the same parts is omitted.

  The crawler belt 1 in the crawler-type work machine is wound in an elliptical shape around a sprocket 7, an idler 6, a lower roller 8, and the like as shown in FIG. The crawler belt 1 is composed of a crawler belt chain in which ends of a plurality of links 3 are connected endlessly by connecting pins 4 and a crawler plate 2 joined to one surface of each link. Further, as shown in FIG. 1 (B), the link 3 has a bush hole (link connecting port) 15 in the vicinity of one end thereof, and a pin hole (link connecting port) in the vicinity of the other end. 16 is formed. The link 3 has a tread 13 arranged so as to connect the bush hole 15 and the pin hole 16 above. The tread surface 13 is formed by a single plane on the opposite side of the attachment surface 14 of the link 3 with the crawler plate 2.

  In the conventional link, the hardness of the tread surface is uniformly formed, whereas in the link according to the present embodiment, the hardness of the tread surface 13 is distributed as shown in FIG. That is, a hardness difference is formed on the tread 13. Specifically, a portion located near both ends of the tread surface 13 is formed with a lower hardness than a portion located in the center of the tread surface 13. The part located in the vicinity of both ends in the tread surface 13 is a part on the substantially end side from the upper position of the centers 15a and 16a of the bush hole 15 and the pin hole 16, respectively. The tread width of the part is formed narrower than the tread width of the part located in the center (shown in FIG. 7A). The part located in the vicinity of both ends of the tread 13 is a part that contacts the lower wheel 8 of the tread 13 of the link when the crawler belt is driven. When the crawler belt is driven, the tread surface 13 also contacts the idler 6 in addition to the lower roller 8, and the contact portion is a central portion in the left-right direction of the tread surface 13 shown in FIG. Since the wear at the contact portion with the idler 8 is usually lighter than the wear at the contact portion with the lower roller 8, no hardness difference is provided in this embodiment. However, if the wear of the contact portion with the idler 8 cannot be neglected due to the structure of the crawler belt device, it is preferable to provide a hardness difference in the same manner.

  Further, the hardness of the portion located near both ends of the tread surface 13 of the link is preferably lower by 3 points or more on the Rockwell hardness C scale (HRC) than the portion located in the center of the tread surface 13. In this embodiment, as shown in FIG. 1 (A), the portion located near both ends of the tread surface 13 is 48.5 on the Rockwell hardness C scale, and the portion located in the center of the tread surface 13 is Rockwell hardness C. The scale is 55.

Next, a method for manufacturing the link 3 will be described.
First, a round or square material of high tough wear-resistant steel is prepared as a raw material. High toughness wear resistant steel is 0.30-0.45 wt% C, 0.10-0.50 wt% Si, 0.30-1.20 wt% Mn, 0.010 wt% or less. P, 0.010 wt% or less S, 0.50 to 1.40 wt% Cr, 0.15 to 0.55 wt% Mo, 0.0005 to 0.0050 wt% B, 0.015 ~ 0.060 wt% Sol. It contains Al, 0.02 to 0.05% by weight of Nb and / or 0.01 to 0.03% by weight of Ti, and the balance is substantially made of Fe.

  Next, the link material in a state close to the finished product is formed by hot forging the material.

  Next, after hot forging, it is naturally cooled and subjected to required machining on an easily processed link material having a relatively low hardness. Thereby, the tread surface 13, the shoe mounting surface 14, the bush hole 15, the pin hole 16, the seal counter bore, the shoe bolt hole, the shoe nut seat surface, and the like are formed. At this time, for example, the bush hole 15, the pin hole 16, the seal counter bore, and other parts where dimensional accuracy is important are limited to rough machining. On the other hand, for example, portions having normal tolerances such as the tread surface 13, the shoe mounting surface 14, the shoe bolt hole, the shoe nut seating surface, and other portions where dimensional accuracy is not so important are not only rough processing but also correspondingly substantial. It is also possible to go through the finishing process. Of the parts to be subjected to the machining, the machining can be omitted for those having the same dimensional tolerance as the roughing in the forming by the hot forging. It is.

  Next, the following heat treatment process is performed on the entire link material subjected to the machining. That is, the entire link material is quenched by quenching the link material from a temperature of 750 ° C. or higher (preferably about 850 ° C.) using water, oil, a solible or an equivalent quenching agent. Thereafter, the link material is subjected to a low-temperature tempering process in which the link material is tempered in a temperature range of 150 ° C. to 300 ° C. so as not to destroy the martensite structure formed by the quenching. Specifically, the tempering process is performed at a higher temperature on the part located near both ends of the tread surface 13 of the link than the part located in the center of the tread surface 13. Through such a heat treatment step, the entire substrate of the link material is cured, and the hardness from the tread surface 13 to at least the core (depth is about 30 mm) is as shown in FIG. .

  The said low temperature tempering process is demonstrated in detail, referring FIG. 1 thru | or FIG. FIG. 2 is a configuration diagram showing an outline of an apparatus for tempering a link. FIG. 3 is a cross-sectional view of the tempering device shown in FIG.

  As shown in FIG. 2, the link 3 is conveyed to the tempering device 21 and stopped in the tempering device 21 for a predetermined time. The tempering device 21 has a housing 22 as shown in FIG. 3, and a low frequency coil 23 is wound inside the housing. By applying a voltage to the coil 23, the link in the coil is heated by the eddy current. At this time, as shown in FIGS. 3 and 1A, a portion of the tread surface 13 other than the vicinity of both ends is covered with an insulator 24 having a thickness of about 15 mm. That is, the insulator 24 is disposed between the coil 23 and the portion other than the vicinity of both ends of the tread surface 13. For this reason, the tempering temperature of the tread surface of the portion covered with the insulator 24 is lower than that of the portion not covered with the insulator. In detail, the part (part which is not covered with an insulator) located near both ends in the tread surface 13 of the link 3 is set to a tempering temperature of about 180 ° C., for example, and the part located in the center of the tread surface 13 (covered with an insulator). For example, a tempering temperature of about 280 ° C. Accordingly, as shown in FIG. 1 (A), the portion located near both ends of the tread surface 13 is set to 48.5 on the Rockwell hardness C scale, and the portion located in the center on the tread surface 13 is represented on the Rockwell hardness C scale. 55.

  When the tempering process is completed, the link 3 is unloaded from the tempering device 21, and the link to be tempered next is transferred into the tempering device 21. A plurality of links can be tempered by repeating such processing.

  Note that various insulators can be used as the insulator 24, and for example, a silicon steel plate is preferably used.

  In the present embodiment, the links are tempered using the tempering apparatus shown in FIGS. 2 and 3, but the present invention is not limited to this, and other tempering apparatuses can also be used. For example, after tempering the entire tread surface of the link at a temperature of 180 ° C., it is possible to temper the portion located near both ends of the tread surface at a temperature of 280 ° C. again. Further, by changing the number of turns of the coil 23 shown in FIG. 1B, more specifically, the number of turns of the coil located near the both ends of the tread is increased, and the number of turns of the coil located on the tread other than near both ends is increased. By reducing the tempering temperature and adjusting the tempering temperature by the number of turns of the coil, it is possible to provide a hardness difference on the tread without using the insulator 24.

  According to the said embodiment, compared with the center site | part, the hardness of the site | part of the both ends vicinity is performed by tempering the site | part located in the tread surface 13 of the link 3 at a high temperature compared with the site | part located in the center. And can be formed low. Near the both ends of the tread surface is a position where the wheel and idler do not come in contact with each other, and therefore, the amount of wear is less than that of the portion located at the center of the tread surface 13. Further, the portion located above the bush hole 15 and on the center side of the tread surface 13 has a larger amount of wear because the tread width is smaller than the portion located in the center of the tread surface. Therefore, by forming the hardness in the vicinity of both ends of the tread 13 to be lower than that at the center, it is possible to reduce the level difference that occurs on the tread 13 due to the difference in wear during use. As a result, it is possible to lengthen the interval for performing maintenance so that the tread surface 13 of the link 3 is shaved so that the tread surface becomes a flat surface. Also, the wear life of the link can be extended. Therefore, the maintenance cost can be reduced, and the link can be used up to the wear limit. Therefore, the cost can be reduced by reducing the number of link replacements. Moreover, since the level | step difference which arises in the tread 13 can be reduced, a vehicle body vibration can be decreased.

  FIG. 4B is a diagram specifically showing the hardness distribution of the treads of the link manufactured by the link manufacturing method according to the present embodiment and the conventional link, and FIG. 4A is shown in FIG. It is a figure which shows concretely the level | step difference wear amount of the tread after running for the predetermined time using the link which has the tread shown in the driving | running | working apparatus shown in FIG.

  Reference numeral 25 shown in FIG. 4B indicates the hardness distribution of the tread surface of the link manufactured by the link manufacturing method according to the present embodiment on the Rockwell hardness C scale. It shows the hardness distribution of the link. Reference numeral 27 shown in FIG. 4A indicates the step wear amount of the tread having the hardness distribution of reference numeral 25, and reference numeral 28 indicates the step wear of the tread having the hardness distribution of reference numeral 26. It shows the amount.

  4 (A) and 4 (B), it was confirmed that by providing a difference in hardness on the tread like the link according to the present embodiment, the step generated on the tread can be reduced due to the difference in the amount of wear during use. Specifically, in the link having a difference in hardness on the tread, the step 29 caused by wear was about 4 mm, whereas in the link having a uniform tread surface, the step 30 caused by wear was 8 mm. It was about. Therefore, if the link according to the present embodiment is used, the level difference can be reduced to about half.

  In addition, this invention is not limited to the said embodiment, It can be implemented in various changes within the range which does not deviate from the main point of this invention.

(A) is a figure which shows the hardness distribution of the tread of the link by one Embodiment of this invention, (B) is a side view which shows the link provided with the tread which has the hardness distribution shown to (A). is there. It is a block diagram which shows the outline of the apparatus which performs tempering of a link. It is sectional drawing of the tempering apparatus shown in FIG. (B) is a figure which shows the hardness distribution of each tread of the link by one Embodiment of this invention, and the conventional link, (A) is a figure which shows the level | step difference wear amount of the link which has a tread shown to (B). is there. It is a block diagram which shows the traveling apparatus provided with the link. FIG. 6 is a partially exploded perspective view of the crawler belt shown in FIG. 5. (A) is a top view which shows the tread of the link shown in FIG. 6, (B) is the figure which looked at the link provided with the tread shown in (A) from the side.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Crawler belt 2 Crawler plate 3, 3b Link 4 Connection pin 5 Track frame 6 Idler 7 Sprocket 8 Lower roller 9a, 9b Roller 10 Traveling device 11 Bush 12 Dust seal 13 Tread 14 Shoe attachment surface 15 Bush hole (link connection port)
16 pin hole (link connection port)
17 shoe nut seat surface 18 window portion 19 portion located above the link connecting port 20 portion located above the bushing hole and on the center side of the tread surface 21 tempering device 22 housing 23 low frequency coil 24 insulators 29, 30 steps

Claims (6)

In a crawler belt that is wound around a sprocket, idler, or wheel in a crawler work machine, to which a crawler plate is attached, and in a link that is annularly connected by pin coupling to form a crawler chain,
The link has a mounting surface of the crawler plate and a tread surface at a position facing the mounting surface,
The tread has a flat surface, and a part of the flat surface has a contact portion with an idler and / or a wheel at the time of crawler belt drive,
The link is characterized in that the portion of the flat surface excluding the contact portion is formed with a lower hardness than the contact portion. In the crawler track of a crawler type work machine, in a link forming an annular crawler chain by connection,
The link has a link connecting port at both ends thereof, and has a tread surface arranged so as to connect the upper side of one link connecting port and the upper side of the other link connecting port,
The link in which the site | parts near the both ends in the said tread are formed low in hardness compared with the center site | part in this tread.   3. The link according to claim 2, wherein the hardness of a portion near the both ends of the tread is 3 points or more lower on the Rockwell hardness C scale than the center portion of the tread.   The portion near both ends of the tread is a portion closer to the end than the center upper position of the link connection port, and the tread width of the portion is narrower than the tread width of the center portion of the tread. Item 3. The link according to item 2.   The link according to claim 4, wherein the hardness of a portion near both ends of the tread is 3 points or more lower on the Rockwell hardness C scale than the central portion of the tread. In a method for manufacturing a link in a crawler track of a crawler-type work machine and forming an annular crawler chain by connection,
The link has a link connecting port at both ends thereof, and has a tread surface arranged so as to connect the upper side of one link connecting port and the upper side of the other link connecting port,
A method for manufacturing a link, comprising tempering a portion near both ends of the tread at a temperature higher than that of a central portion of the tread.

Images