Centrifugal casting process for piston rods and centrifugally cast piston rods

Abstract

The present invention relates to a process for centrifugally casting a piston rod and a centrifugally cast piston rod. The process includes: S1, loading a mold onto a centrifuge and starting the centrifuge. The casting cavity of the mold has a large-diameter end and a small-diameter end; S2, pouring gray cast iron molten iron at a temperature of T1 into the large-diameter end of the mold, and withdrawing the sprue after pouring to cast the outer layer of the large-diameter end of the piston rod; S3, after the gray cast iron molten iron cools down to T2, pouring chilled cast iron molten iron at a temperature of T3 into both the large-diameter end and the small-diameter end of the mold so that the chilled cast iron molten iron is completely combined with the outer layer of the large-diameter end of the piston rod; S4, after the chilled cast iron molten iron cools down to T4, turning off the centrifuge. The centrifugally cast piston rod of the present invention can take into account the performance requirements of both the large-diameter end and the small-diameter end at the same time.

Description

Technical Field

[0001] The present invention relates to the field of piston rods, and particularly to a centrifugal casting process for piston rods and a centrifugally cast piston rod. Background Art

[0002] The piston rod in a large hydraulic press consists of two parts. The first part is the large-diameter end for slotting to install the seal, and the second part is the small-diameter end as the working surface. The working surface of the piston rod functions as a sliding surface. Therefore, the outer peripheral surface of the second part requires high hardness, wear resistance, and corrosion resistance. However, at the same time, the first part needs to be slotted to install the seal, and too high hardness can easily lead to difficult machining and the slot edges are prone to bursting, thus causing problems such as scratching of the seal. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a centrifugally cast piston rod that can take into account the performance requirements of both the large-diameter end and the small-diameter end.

[0004] To solve the above technical problem, the technical solution of the present invention is: A centrifugal casting process for piston rods, comprising:

[0005] S1, loading the mold onto the centrifuge and starting the centrifuge. The casting cavity of the mold has a large-diameter end and a small-diameter end;

[0006] S2, pouring gray cast iron molten metal at temperature T1 into the large-diameter end of the mold, and withdrawing the pouring gate after pouring to cast the outer layer of the large-diameter end of the piston rod;

[0007] S3, after the gray cast iron molten metal cools down to T2, pouring chilled cast iron molten metal at temperature T3 into both the large-diameter end and the small-diameter end of the mold, so that the chilled cast iron molten metal is completely combined with the outer layer of the large-diameter end of the piston rod;

[0008] S4, after the chilled cast iron molten metal cools down to T4, shutting down the centrifuge.

[0009] Further, the range of T1 is 1450 - 1550 °C;

[0010] and / or the range of T2 is 1200 - 1300 °C;

[0011] and / or the range of T3 is 1450 - 1500 °C;

[0012] and / or the range of T4 is 1200 - 1300 °C.

[0013] Further, the centrifugal casting process for piston rods further comprises:

[0014] S5. Stand the mold upright and place it in the bottom mold. Then pour gray cast iron molten iron at temperature T5 into the mold to cast the centers of the large-diameter end and the small-diameter end of the piston rod.

[0015] Furthermore, the range of T5 is 1450°C - 1480°C.

[0016] Furthermore, the centrifugal casting process of the piston rod further includes:

[0017] S6. Demold and process after cooling.

[0018] Furthermore, the mass percentages of the components of the chilled cast iron molten iron are as follows:

[0019] C: 2.90% - 3.6%; Si: 0.25% - 0.8%; Mn: 0.5 - 1%; P: 0 - 0.4%; S: 0 - 0.1%; Cr: 0.5 - 1.5%; Mo: 0.32 - 0.4%; Ni: 0.5 - 1.5%; the balance is Fe.

[0020] The present invention also provides a centrifugally cast piston rod, which includes a chilled cast iron inner layer and a gray cast iron outer layer provided on the outer peripheral wall of one end of the chilled cast iron inner layer. The gray cast iron outer layer forms the large-diameter end of the centrifugally cast piston rod, and the part of the chilled cast iron inner layer that is offset from the gray cast iron outer layer forms the small-diameter end of the centrifugally cast piston rod. Both the chilled cast iron inner layer and the gray cast iron outer layer are centrifugally cast.

[0021] Furthermore, the centrifugally cast piston rod further includes a gray cast iron core column provided in the central region of the chilled cast iron inner layer.

[0022] Furthermore, the two end faces of the gray cast iron core column are flush with the chilled cast iron inner layer respectively.

[0023] After adopting the above technical solutions, the present invention uses the method of centrifugal composite casting. The outer layer of the large-diameter end of the piston rod is made of gray iron, and the inner layer of the large-diameter end and the small-diameter end are made of high-alloy chilled cast iron. The gray iron material has a relatively low hardness, so that the large-diameter end of the piston rod has a lower hardness, and thus can be well grooved to install the seal. The chilled cast iron has a high hardness, so that the small-diameter end of the piston rod has a high hardness and is wear-resistant and corrosion-resistant. The piston rod cast in the present invention can simultaneously meet the performance requirements of both the large-diameter end and the small-diameter end; the entire piston rod is centrifugally cast, and the gray iron material and the chilled cast iron material can be perfectly solidified and combined together. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic structural diagram of the centrifugally cast piston rod of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] In order to make the content of the present invention easier to be clearly understood, the present invention will be further described in detail below with reference to specific embodiments and the accompanying drawings.

[0026] Embodiment 1

[0027] A centrifugal casting process for piston rods, characterized in that

[0028] It includes:

[0029] S1, loading the mold onto the centrifuge and starting the centrifuge. The casting cavity of the mold has a large-diameter end and a small-diameter end;

[0030] S2, pouring gray cast iron molten iron at temperature T1 into the large-diameter end of the mold. After pouring, withdraw the sprue to cast the outer layer of the large-diameter end of the piston rod;

[0031] S3, after the gray cast iron molten iron cools down to T2, pour chilled cast iron molten iron at temperature T3 into the large-diameter end and the small-diameter end of the mold, so that the chilled cast iron molten iron is completely combined with the outer layer of the large-diameter end of the piston rod;

[0032] S4, after the chilled cast iron molten iron cools down to T4, turn off the centrifuge;

[0033] The outer layer of the large-diameter end of the piston rod is made of gray iron, and the inner layer of the large-diameter end and the small-diameter end are made of high-alloy chilled cast iron. The hardness of the gray iron material is relatively low, so that the hardness of the large-diameter end of the piston rod is relatively low, and thus it can be well grooved to install the seal. The hardness of the chilled cast iron is high, so that the small-diameter end of the piston rod has a high hardness and is wear-resistant and corrosion-resistant. The piston rod cast in this embodiment can meet the performance requirements of both the large-diameter end and the small-diameter end at the same time; by centrifugal casting, the outer gray iron material and the inner chilled cast iron material can be perfectly solidified and combined together.

[0034] S5, stand the mold upright and place it in the bottom mold, and then pour gray cast iron molten iron at temperature T5 into the mold to cast the center of the large-diameter end and the center of the small-diameter end of the piston rod;

[0035] The center of the piston rod is made of gray cast iron material. On the premise of meeting the hardness, wear resistance and corrosion resistance of the small-diameter end of the piston rod, the usage amount of chilled cast iron can be reduced as much as possible.

[0036] S6, demold and process after cooling.

[0037] In this embodiment, generally, T1 is in the range of 1450-1550° C., preferably 1450° C.; T2 is in the range of 1200-1300° C., preferably 1200° C.; T3 is in the range of 1450-1500° C.; T4 is in the range of 1200-1300° C., preferably 1200° C.; T5 is in the range of 1450° C.-1480° C. During the production process, infrared temperature measurement and timing are performed.

[0038] In this embodiment, the mass percentages of the components of the chilled cast iron molten iron are:

[0039] C: 2.90%-3.6%; Si: 0.25%-0.8%; Mn: 0.5-1%; P: 0-0.4%; S: 0-0.1%; Cr: 0.5-1.5%; Mo: 0.32-0.4%; Ni: 0.5-1.5%; the balance is Fe.

[0040] In this embodiment, before S1, the process further includes: calculating the weight of the outer layer of gray cast iron liquid, the inner layer of chilled cast iron liquid and the center gray cast iron liquid according to the products of different specifications, and melting the respective molten irons. The composition of the gray cast iron is HT250.

[0041] Embodiment 2

[0042] like Figure 1 As shown, a centrifugally cast piston rod comprises a chilled cast iron inner layer 2 and a gray cast iron outer layer 1 which is arranged on the outer peripheral wall of one end of the chilled cast iron inner layer 2, wherein the gray cast iron outer layer 1 forms the large diameter end of the centrifugally cast piston rod, and the portion of the chilled cast iron inner layer 2 offset from the gray cast iron outer layer 1 forms the small diameter end of the centrifugally cast piston rod, and both the chilled cast iron inner layer 2 and the gray cast iron outer layer 1 are formed by centrifugal casting.

[0043] like Figure 1 As shown, the centrifugally cast piston rod further comprises a grey cast iron core column 3 arranged in the central area of the chilled cast iron inner layer 2 .

[0044] like Figure 1 As shown, two end surfaces of the grey cast iron core column 3 are flush with the chilled cast iron inner layer 2 respectively.

[0045] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A centrifugal casting piston rod process, characterized in that: include: S1, loading a mold onto a centrifuge and turning on the centrifuge, wherein the casting cavity of the mold has a large diameter end and a small diameter end; S2, pouring molten gray cast iron at a temperature of T1 into the large diameter end of the mold, and withdrawing the gate after pouring to cast the outer layer of the large diameter end of the piston rod; S3, after the gray cast iron liquid is cooled to T2, pouring the chilled cast iron liquid at a temperature of T3 into the large diameter end and the small diameter end of the mold, so that the chilled cast iron liquid is completely combined with the outer layer of the large diameter end of the piston rod; S4, after the chilled cast iron molten iron is cooled to T4, the centrifuge is turned off; S5, stand the mold upright and put it into the bottom mold, then pour gray cast iron liquid with a temperature of T5 into the mold to cast the center of the large diameter end and the center of the small diameter end of the piston rod.

2. The centrifugal casting piston rod process according to claim 1, characterized in that: The range of T1 is 1450-1550℃; and / or T2 is in the range of 1200-1300°C; and / or T3 in the range of 1450-1500°C; and / or T4 is in the range of 1200-1300°C.

3. The centrifugal casting piston rod process according to claim 1, characterized in that: The range of T5 is 1450℃-1480℃.

4. The centrifugal casting piston rod process according to claim 1, characterized in that: Also includes: S6, demoulding and processing after cooling.

5. The centrifugal casting piston rod process according to claim 1, characterized in that: The mass percentage of each component of the chilled cast iron molten iron is: C: 2.90%-3.6%; Si: 0.25%-0.8%; Mn: 0.5-1%; P：0-0.4%； S: 0-0.1%; Cr: 0.5-1.5%; Mo: 0.32-0.4%; Ni: 0.5-1.5%; the balance is Fe.

6. A centrifugally cast piston rod, characterized in that: It comprises a chilled cast iron inner layer (2) and a grey cast iron outer layer (1) provided on the outer peripheral wall of one end of the chilled cast iron inner layer (2), the grey cast iron outer layer (1) forming a large diameter end of a centrifugally cast piston rod, and a portion of the chilled cast iron inner layer (2) offset from the grey cast iron outer layer (1) forming a small diameter end of the centrifugally cast piston rod, and the chilled cast iron inner layer (2) and the grey cast iron outer layer (1) are both centrifugally cast; It also includes a grey cast iron core column (3) arranged in the central area of the chilled cast iron inner layer (2).

7. The centrifugally cast piston rod according to claim 6, characterized in that: The two end surfaces of the grey cast iron core column (3) are respectively flush with the chilled cast iron inner layer (2).

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