Abstract:
Sand casting remains one of the primary processes for producing complex parts. The technical difficulty of producing these parts, the rationality of auxiliary equipment configuration, and the degree of process integration are closely related to the design of the molding line. Addressing issues such as unstable sand mold transportation and positioning, low sand box recycling efficiency, low production efficiency, and redundant human resources in current sand casting production lines, this paper introduces the design of a fully automatic horizontal parting molding line. This line includes key components such as the overall layout of the production line, bottom plate clamping mechanisms, sleeve box and weight conversion devices, bottom plate conversion devices, sand mold ejection devices, and sand trough belt conveyors. It also utilizes a Programmable Logic Controller (PLC) to precisely control the coordinated operation of each key component, achieving automated control of the production process. Practical applications have shown that the designed fully automatic horizontal parting molding line can realize automatic molding, pouring, and sand shakeout of sand casting products, effectively improving production line space smoothness and efficiency, reducing human labor intensity, and optimizing the production environment.
1. Introduction
Statistics indicate that in 2018, China’s casting production accounted for nearly 44% of the global total. Therefore, the casting industry has put forward higher requirements for the production cost, efficiency, and scale of sand casting. The horizontal parting sleeve box mode is one of the main molding processes in foundries. Compared with manual molding, shock and pressure mechanical molding, and static pressure molding, it has the advantages of simple structure, low investment, and easy separation of sand and iron. It is widely used in industries such as industrial pumps and valves, agricultural machinery, and automobile component manufacturing. To improve casting molding rates and achieve full automation, researchers have conducted extensive research on molding lines under different process modes.
2. Overview of the Design Task
A casting workshop of a certain company has an area of 140m×24m and mainly produces two types of castings: automobile hubs and clutches. The grades of the castings are both HT250, and the required sand box sizes (length × width × height) are 610mm×610mm×280400mm and 570mm×670mm×360560mm, respectively. The average weights of the castings for the two sand box sizes are approximately 20kg and 40kg, respectively. Operating on a two-shift, 8-hour work system for 300 days a year, the production line needs to meet the following performance indicators: 1) A casting finished product rate of 90%; 2) Adjustable sand height to accommodate different sand box thicknesses; 3) Increased production capacity to 12,000 tons per year (equivalent to 440,000 sand boxes per year).
3. Layout and Workflow of the Fully Automatic Horizontal Parting Molding Line
3.1 Layout
The product molding method, equipment configuration, and transfer process in the production line directly affect product quality, production efficiency, and employee safety. Reasonable design and optimization of the molding line layout can maximize the efficiency of the production line. This paper uses two identical horizontal parting molding machines for sand molding. These machines have the function of flexibly adjusting the thickness of the sand mold and can communicate with the sand storage and sand mold conveyor to establish the foundation for fully automated control. The fully automatic horizontal parting molding workshop has a total of four conveyor lines in the front and rear areas, including a pouring conveyor line, a sand mold ejection transition conveyor line, and two cooling conveyor lines.
3.2 Workflow
The basic workflow of the molding line is as follows: molding system activation – sand supply signal issuance – horizontal parting sand conveying – molding – bottom plate clamping and positioning – sand mold ejection to the first conveyor line – clamping device positioning – sleeve box and weight conversion to the pouring platform – positioning – pouring – cooling – positioning – sleeve box and weight conversion – sand mold pushing into the vibrator – sand shaking – cleaning – casting output. The old sand recovery system in the pit transports old sand at a certain speed, and the above process can be recycled.
4. Key Mechanical Structures Design
4.1 Molding System Structure
The molding system uses compressed air to inject molding sand into the sand box for sand filling and pre-compaction, followed by supplementary compaction. The molding system establishes a connection between the sand preparation device and the horizontal molding line, ensuring timely sand supply after automatic molding and automatic transportation of the sand mold to the molding line. The molding system mainly consists of upper and lower box molding modules, pusher mechanisms, sand cylinders, and other components.
4.2 Sleeve Box and Weight Conversion Device
(Detailed description and diagram of the sleeve box and weight conversion device can be included here, with an image)
5. Automatic Conveyor Unit Design
The sand mold automatic conveyor unit ensures stable transportation, improves molding rates, and reduces production costs. It consists of four steel welded support light rails, bottom plate trolleys, bottom plate conversion devices, and sand mold ejection devices. The bottom plates on the light rails are pushed by the bottom plate conversion device. Bottom plate clamping and positioning devices are installed at the light rail positions for pushing the mold, pouring, and sleeve box and weight lifting mechanisms, achieving stable sand mold transportation.
6. Control System Design
6.1 Overall Control Flow
The core of the control system is realized through PLC control. When the PLC issues a molding signal, servo motors, hydraulic systems, and pneumatic systems drive the various axes/columns to sequentially perform processes such as mold closing, sand injection, compaction, mold opening, core insertion, mold receiving and closing, mold receiving and stripping, and mold pushing.
6.2 PLC Control System
The PLC communicates with remote input/output (I/O) devices or specialized automation equipment via CCLINK. The main station CPU adopts FX5U-80MT, and the remote I/O stations use AJ65SBTB1-16D modules and AJ65SBTB2N-16R to connect input/output devices. Input devices include control buttons, touchscreens, and sensors; output devices mainly include servo drives, motors, heaters, hydraulic coolers, and solenoid valves. Data exchange between the PLC control system and the information system is achieved through Ethernet and industrial internet technology for production process monitoring and management.
Table 1: I/O Address Allocation of the Main Station PLC
| I/O Type | Address Range | Description |
|---|---|---|
| Input | X000-X015 | Control buttons, sensors, etc. |
| Output | Y000-Y015 | Servo drives, motors, heaters, etc. |
| (Continued…) | (Continued…) | (Continued…) |
(The table can be expanded as needed to include all I/O addresses)
7. Operation and Analysis of the Fully Automatic Horizontal Parting Molding Line
Taking automobile hubs and clutches as examples, The fully automatic horizontal parting molding line designed in this paper. It mainly includes a molding system, pouring and cooling conveyor lines, sleeve box and weight conversion devices, bottom plate conversion devices, pouring machines, sand mold ejection devices, sand shaking machines, scale conveyors, and old sand recovery and transportation lines.
After practical testing, the fully automatic horizontal parting molding line can ensure product quality and stable production line operation. The practical application scenario of the fully automatic horizontal parting molding line.
Table 2: Comparison Before and After the Use of the Fully Automatic Horizontal Parting Molding Line
| Production Mode | Number of Employees | Area Occupancy/% | Production Capacity |
|---|---|---|---|
| Manual Casting Production | 32 | 87.3 | 28.8 |
| This Production Mode | 4 | 65.2 | 46.4 |
Through practical application testing, the fully automatic horizontal parting molding line designed in this paper reduces human resource requirements and labor costs, significantly improves production efficiency, meets customer demand indicators, and effectively improves the workshop working environment with pit belt recovery devices and vacuum dust collectors.