Study on diagonal hammer of three kind metals composite casting with block protecting handle

Hammer crusher is widely used in cement, ceramic, mining and electricityother industries, hammer head is one of important parts in crusher, its abrasion performance directly affects the service life of hammer crusher and economic cost. According to bimetalcomposite hammer head is often appear "Hammer handle wear and tear","Composite difficult" and the set of casting alloy block hammer head set piece of "come off" phenomenon, which design a set piece type bimetal composite casting straight diagonal hammer, make full use of high chromium cast iron wear resistance and the toughness of low alloy steel.Design a protect block structure reasonably that solve the hammer when the actual production of composite interface is difficult to control and "the problem of hammer head wear"for use.Solve the problem of hammer head wear actively, achieve "energy saving, emission reduction and environmental protection".


Introduction
Hammer crusher iswidely used to cement, metallurgy, mining, coal, building materials, transportation and other industries, mining of the ore is high speed rotating hammer broken into grinding material, the workload is very heavy.Hammer crusher is one of the shortest life and the biggest parts of consumption.And Hammer head basically has single material hammer head, cast in alloy block hammer head, doubleliquid metal composite hammer head.
High manganese steel was made earlier crusher hammers and common one kind of material, but some broken material impact is not strong,the work hardening of high manganese steel can't display,high manganese steel wear fast, short service life and so on problems, and Single material of hammer head can't meet the needs of high toughness and high wear resistance.Cast in alloy block hammer head often set piece of "come off", Bimetal composite hammer head is often appear "Hammer handle wear and tear" and "Composite difficult" phenomenon.After the wind quenching heat treatment, the hardness of high chromium cast iron is more than 62 HRC, impact toughness for 3~6 J/cm2;

Microhardness
The hardness of low alloy steel is 180~250HB, impact toughness is greater than 70 J/cm2; To protect the handle piece of 55 HRC hardness above [9], impact toughness for 6~8 J/cm2.

Conclusions
(1)This article can completely solve the set piece "come off" of casting in alloy block type hammer head, bimetal composite oblique hammer often appear "handle" and "complex difficulties" and so on.
(2)Using liquid-liquid composite casting echno-logy, the composite interface routine jagged state, can obtain complete metallurgical bonding of bime-tallic interface bonding area; Liquid-solid com-pound can achieve certain mechanical connec-tion and part of the metallurgical bonding.
(2)Through the wind quenching heat treatment process, under the conditions of equal protection of the handle to block the service life of straight bevel hammer, higher than the single fierce steel hammer head high 3~5 times, abrasion resistance and toughness is improved obviously.

2 Testing materials and methods 2 . 1
figure 1b) is good toughness of low alloy steel material, and the hammer end (as shown in figure 1c) is to use high wear resistance of high chromium cast iron material.The study of the hammer head of simple structure, not only solved the "handle" phenomenon, but also solves the caused by the external environment and the level of workers is not enough "composite difficulty" problem.And without affecting the original under the premise of use function, greatly extend the service life of the whole, reduce the maintenance cost and use cost of the enterprise.Straight bevel hammer structure as shown in figure 2 [2].

Figure 1protect the handle
Figure 1protect the handle schematic block type straight diagonal hammer decomposition a) protect the handle piece b) hammer handle c) side

Figure 2
Figure 2 protect the handle type straight diagonal hammer piece of structure 1 Side 2 Hammer handle 3 Protect the handle piece 4 Jack 5 Waist type hole 2.2 Determine the chemical composition of composite materials In order to make protect the handle piece, side, hammer handle to achieve their ideal abrasion resistance and toughness, in this article, use the high carbon high chromium steel armor handle with better abrasion resistance, and hammer end is high abrasion resistance of high chromium cast iron, the hammer handle is toughness good low alloy steel.According to the needs of the effect of alloy elements and the performance of the belt can be determined to protect the handle of the chemical composition of each place straight diagonal hammer as shown in table 1.

2. 3
Heat treatment process This study chooses the wind quenching heat treatment process, the austenitizing temperature heated to 1020 ,then use the air-filled.Will tempering temperature heated to 230 , and continue to air cooling.Research on heat treatment process to observe straight diagonal hammer's the law of the performance, thusb a c DOI: 10.1051/ 03011 (2016) , matecconf/2016 MATEC Web of Conferences 63 630 ensuring a good comprehensive mechanical properties.Heat treatment process curve is shown in figure 3[3].

Figure 3 heat treatment process curve 2 . 4 Figure 4
Figure 3 heat treatment process curve Figure 5three types metal composite interface organization characteristics a) high chromium cast iron/low alloy steel low alloy steel b) low alloy steel/high carbon high chromium steel Figure 5(a) liquid-liquid composite icrostructure characteristics.Composite interface can be seen in the metallographic photos showing a small serrated, appear the phenomenon of melting and mutual penetration.And composite interface no shock phenomenon, compact structure, achieve ideal metallurgical bonding state [7].

Figure 5 (
Figure 5 (b) solid-liquid composite microstructure observation, In metallographic figure, you can see the interface without micro crack, blowhole and inclusions, etc..Formed a similar liquid-liquid double metal composite of straight line.So in the combination of fluid of low alloy steel with high carbon high chromium steel interface to achieve complete metallurgical bonding state[8].

Figure 6
Figure 6 microhardness bimetallic interface bonding area Through the analysis of the microhardness: If the interface has a good combination of area, the microhardness should gradient smooth transition, and measured the hardness of low alloy steel is about 350HV, solid interface combined with the hardness of about 510 HV, fluid interface in combination with the hardness of about 580 HV,

Figure 7
Figure 7 a) straight diagonal hammer handle piece of type b)Real figure