GB2123730A

GB2123730A - Casting apparatus

Info

Publication number: GB2123730A
Application number: GB08321314A
Authority: GB
Inventors: Toru Moritani; Minoru Teramura; Masahiro Shimizu
Original assignee: Sumitomo Metal Industries Ltd
Current assignee: Nippon Steel Corp
Priority date: 1981-09-28
Filing date: 1983-08-08
Publication date: 1984-02-08
Also published as: GB2127338A; FR2526344A1; FR2515080A1; GB2127338B; GB2123730B; GB8321315D0; GB2106809B; IT1157753B; GB2106809A; IT8212626A0; GB8321314D0; DE3235647A1

Abstract

Casting apparatus is described for use in a method of casting and working a cylindrical body. Empty moulds (2) pass in succession to the casting station (B) where each in turn is filled. Initially each is raised, as shown, and load cells (7) associated with hydraulic cylinders (6) connected to the mould support platform pass mould tare weight data to the computer unit (5) where the data is converted to a value for mould height. During mould filling the measured change in mould weight is used to regulate pouring from the ladle (8) and to lower the mould support platform. Molten steel is poured through port (9) to mould (2). Port (9) is controlled by stopper (11), raised and lowered by cylinder (12) controlled by unit (5). Filled moulds are passed slowly to scarfing section (D). <IMAGE>

Description

SPECIFICATION Casting apparatus This invention relates to casting apparatus for use in a method of casting and working a cylindrical body. Attention is drawn to copending application No. 8227475 from which the present application is divided.

For producing steel ingots for annular forgings, there is known, for example as shown in Fig. 1, a long ingot method of casting a long cylindrical steel ingot LI by bottom casting method and then cutting the ingot into round slices on a lathe or the like to provide steel ingots to be rolled, or a cheese ingot method (not shown) of casting molten steel into moulds arranged in series below a ladle by a top casting method, shifting the ladle.

In the former long ingot method, however, a lot of cut-off portions in dead head, centre runner, .sprue runner, cutting allowance, etc. are lost by cutting the steel ingot into round slices and further a lot of heat is lost by cutting the steel ingot after cooling. In the latter, cheese ingot method, if the "ratio of height to diameter" of the steel ingot is more than 1.0, problems of quality in that cavities and defective portions remain in the interior of the steel ingot, are encountered. In addition, problems are encountered with variable quality and further the long casting time is unsuitable for mass casting.

An object of the present invention is to provide a casting apparatus which can measure a required weight of a work unit of steel ingot and take out a necessary amount of molten steel into a mould to measure and cast the ingot accurately and automatically without dead head with reference to the measured value.

The present invention provides a casting apparatus for use in a method of casting and working a cylindrical body, comprising: (a) a weighing machine capable of measuring the weight of a mould at a casting station before and during casting; and (b) a molten steel take-out apparatus for taking out a desired amount of molten steel into the said mould, controlled by a calculating control circuit interlocked with said weighing machine.

The invention will be further described by way of example with reference to the accompanying drawings, in which: Fig. 1 is an explanatory drawing of the conventional long ingot method; Fig. 2 is a schematic view showing a working process for carrying out a method of casting and working a cylindrical body.

Fig. 3 is a partially sectional enlarged view showing casting and working for performing the method illustrated in Fig. 2 and including a casting apparatus; Fig. 4 is a partially sectional side view showing main portions of casting apparatus similar to Fig.

3; Fig. 2 shows a line showing working processes for working of the present invention, in which a mould setting section A, casting section B and mould drawing section C are sequentially arranged in the form of a plain rectangular endless loop as shown in the drawing, for example, and from the mould drawing section C are branched and extended working lines for conveying cast steel ingots to the following process, i.e. scarfing section D, heating furnace E and then rolling section F.

As shown in Fig. 3 a plurality of moulds 2 are arranged and set in series at predetermined positions on a carrier truck 1 in the mould setting section A so as to be conveyed to the following casting section B.

As shown in Figs. 3 and 4, molten steel required for a work unit of casting ingot is cast into the mould 2 in the casting section B on a weighing machine 3 capable of measuring the weight of mould 2 before and during casting and a molten steel take-out device 4 for passing out a necessary amount of molten steel into the mould 2 through a calculating control circuit (computer) 5 interlocked with the weighing machine.

The weighing machine 3 comprises a hydraulic cylinder 6 for supporting and moving vertically the mold 2 with a rod 6' and a load cell 7 mounted on the base of the hydraulic cylinder 6 which is provided to raise the mold 2 from the conveying position up to a position on which the molten steel can be poured. The load cell 7 functions to measure the weight of the mold 2 before casting (tare weight before casting), to apply the measured value and the change in the weight at the beginning of molten steel pouring and during casting sequentially to the input of the calculating control circuit 5.

The molten steel take-out device 4 comprises a dipped nozzle 10 projecting downward from a pouring port 9 of a ladle 8 located above the mold 2, a stopper 11 capable of opening and closing the pouring port 9 and a hydraulic cylinder 1 2 operated by the calculating control circuit 5 to move vertically the stopper 11.

The calculating control circuit 5 receives the input value from the load cell 7 to calculate an amount of molten steel to be poured into the mold 2 and required for casting a work unit of the ingot and supplies the required output to the hydraulic cylinder 12.

The base end (upper end) of the dipped nozzle 10 is mounted on the pouring port 9 of the intermediate ladle 8, and further a cylindrical cover 13 opened at the lower end is provided around the outer periphery of the point of said nozzle to prevent splash in-pouring molten steel. Also, coating 14 for covering the surface of the molten steel W is put into the mold 2.

Further, after casting, exothermic heat insulating agent or a heat insulating plate (plate-shaped heat insulating agent) 1 5 is put onto the upper surface of the molten steel W to carry out exothermic heat insulation in the conveyance of the molten steel.

A speed control unit 1 6 for controlling speed with which the molten steel is conveyed along a conveying path after casting is provided to convey the mold 2' to the following mold drawing section C with minimum speed to avoid abrupt conveyance and swaying the surface of the molten steel W.

In the casting section B thus constituted, the weight of the unit steel ingot to be directly rolled, including tare weight, is previously applied and set to the calculating unit 5 shown in Fig. 3. Then, the mold 2 located in the casting section B on the line is raised toward the puring port 9 of the intermediate ladle 8 by the lifting cylinder 6 to cast the molten steel into the mold 2. Then, the tare weight of the mold is measured by the load cell 7 to be applied to the input of the calculating unit 5. The input value of the calculating unit is converted into the height of the mold 2 to the intermediate ladle 8 so that the output of the calculating unit is applied to the hydraulic cylinder 12 which lifts the stopper 11 directly connected thereto in the intermediate ladle 8.The pointed end of the stopper is raised higher than the pouring port 9 to start pouring into the mold 2'. When the surface of the molten steel W in the mold 2' is sequentially raised, the load cell 7 attached to the lower cylinder 6 detects the change in the weight of molten steel to lower gradualiy the position of the mold 2'.

Accordingly, the capacity of the molten steel W is gradualiy increased without changing the position of the surface of molten steel shown in the drawing, until it provides a predetermined amount of molten steel (amount necessary for an work unit of steel ingot). Meanwhile, the load cell 7 continues to apply the weight change to the input of the calculating unit 5 to measure the predetermined weight so that the hydraulic cylinder 1 2 lowers the stopper 11 and closes the pouring port 9. The stopper may be subjected to multi-stage control to improve the accuracy of taking out the molten steel. Thus, the predetermined steel ingot (steel slab) with the unit weight is casted.

The casting section B, thus constituted, can weigh individually the molds, take out a necessary amount of molten steel through the calculating control circuit, and at the same time cast a plurality of steel ingots with high quality automatically and rapidly (see Table 1). Also, since top pouring using the dipped nozzle and the cylindrical cover are employed, splashing can be prevented to improve the casting skin of the steel ingot.

TABLE 1

Casting Number Average Standard Casting division of casting unit weight deviation time (Fig. 5) (P) (Kg) y(Kg) (Min.) 75 75 440.3 2.7 36 min/75p 76 440.0 2.6 36 min/76p Further, the molten steel coating cover 14 is attached to the outside of the cylindrical cover provided on the pointed end of the nozzle 10 before casting above the upper surface of the molten steel W cast into the mold 2' in said casting section B. After casting, as shown in the drawing, the cover 14 covers the upper surface of the molten steel with the heat insulating agent 1 5 to keep the surface of the molten steel from swaying and retain heat while the molten steel is conveyed.Also, the molten steel, after casting, is prevented from rapid conveyance by the speed control unit 1 6 which holds the minimum conveying speed. Thus, during the conveyance, heat is sufficiently maintained while the steel ingot is sent to the scarfing section D while it is hot without sway so that the inner quality of the ingot changes little and the smooth surface is maintained.

Next, though not shown in the drawing, in the mould drawing section C, the mould is laid down and the steel ingot is drawn out of the mould as it is hot to be sent to the following scarfing section D.

Next will be shown a concrete embodiment which scarfs the steel ingot to provide results shown on Tables 2 and 3 under the following conditions; (Conditions) (1) Material of dipped nozzle; Molten silicon, inside diameter 40 0 Jetting port: Two horizontal ports x 25 0 x 2 (2) Amount of coating (12) to be used: 2KIT Component: sio2 45%; Co 0.8%; Al202 20%; C16% (3) Amount of heat insulating agent (99) to be used: 4K/T Component: MoAI 15%; Al203 40%; siO2 20% (4) Steel ingot: Unit weight 440 Kg, profile 500 X x 285H (5) Mould: Unit weight 1400 kg (mould, bedplate) (6) Kind of steel: C 0.60; Si 0.25; Mn 0.60 (7) Casting speed: 1 5 Kg/sec.

(8) Dimension of steel ingot: (Height/diameter) less than 1.0 (9) Scarf: Height of flux end (outer peripheral portion), more than 10 m/m (10 m/m is the minimum thickness of segregation).

TABLE 2

Casting Scarfing Test No. Number of Average Standard Casting Weight Scarfing casting unit weight deviation time of scarf time () (Kg) sr(Kg) (min) (Kg) (sec/D) First 150 439.4 2.4 72 14.2 33 Second 149 438.7 2.7 70 15.1 34 Third 149 441.5 2.9 71 14.3 33 Fourth 150 440.0 2.1 72 14.4 33 TABLE 3

Quality Test No. Percentage defective Percentage of wheel of wheel conditioning of wheel (%) (%) First O 0 Second O 0 Third 0 0 Fourth O 0 As is apparent from the above, the following advantages are obtained; (1) Homogeneous steel ingots without dispersion of quality, as hot lumps, can be cast and scarfed rapidly in the continuous process from the casting process to the scarfing one and then sent to the following rolling process so that rapid mass production can be obtained.

(2) A plurality of steel ingots can be simultaneously cast by weighing individually the molds and taking out a necessary amount of molten steel through the calculating control circuit so that high quality steel ingots can be automatically rapidly cast (see Table 1). Also, the top casting using the dipped nozzle and the cylindrical cover are utilized so tha the occurrence of splash can be prevented to improve the casting skin of the steel ingot.

Claims

1. Casting apparatus for use in a method of casting and working a cylindrical body, comprising: (a) a weighing machine capable of measuring the weight of a mould at a casting station before and during casting; and (b) a molten steel take-out apparatus for taking out a desired amount of molten steel into the said mould, controlled by a calculating control circuit interlocked with said weighing machine.

2. Apparatus as claimed in claim 1 , wherein said weighing machine comprises a hydraulic cylinder for vertically moving the mould and a load cell mounted on the hydraulic cylinder.

3. Apparatus as claimed in claim 1 or 2, wherein said molten steel take-out apparatus comprises a dipped nozzle projecting downward from a pouring port of a ladle, a stopper capable of opening and closing said pouring port and a hydraulic cylinder operated by said calculating control circuit to vertically move said stopper to open and close the pouring port.

4. Casting apparatus substantially as hereinbefore described with reference to Fig. 3 or Fig. 4 of the accompanying drawings.