Molding machine classification and function introduction

Molding machine classification and function introduction
The molding machine is the core equipment used in casting production to manufacture sand molds (molds). Its core function is to transform loose molding sand into a sand mold with certain strength and precision for pouring molten metal. The following is the classification and function introduction of the molding machine.
1. Classified by molding method (compression principle)
This is the most core classification method, reflecting the development process and level of technology.
1. Vibratory molding machine
Principle: Using compressed air to make the worktable (or sand box) and the molding sand rise rapidly and then suddenly fall, generating shock vibration, causing the molding sand to be compacted due to inertial force.
Characteristics: Simple equipment, low cost. However, it has high noise, high energy consumption, uneven compactness (top loose and bottom tight), low productivity, and high requirements for the foundation. It has basically been eliminated or only used in special occasions such as maintenance.
2. Impact molding machine
Principle: First, it vibrates to make the bottom molding sand compact, and then uses a pressing cylinder (or hydraulic cylinder) to supplement the pressing of the top of the sand mold to improve overall uniformity.
Characteristics: It is better than simple vibration, and was once the mainstream equipment in small and medium-sized casting factories. However, it still has noise and efficiency problems, and the surface hardness and flatness of the cavity are average.
3. Compacting molding machine
Principle: Simply using an air pressure or hydraulic pressure-driven pressing head (flat pressing head, forming pressing head, or multi-contact pressing head) to statically compact the molding sand from above or below the sand box. Feature:
Simple compaction: Simple structure, low noise, but the compactness decreases severely along the height direction (tight at the top and loose at the bottom).
Multi-contact compaction: Each press head's small hydraulic cylinder can adapt to the height variation of the mold, making the compaction more uniform and suitable for complex molds.
High-pressure compaction: Using a higher specific pressure (usually > 0.7 MPa), high hardness and high precision sand molds can be obtained.
4. Pressurized molding machine
Principle: Utilizing compressed air to instantly shoot the molding sand at high speed into the sand box (filling the sand), followed by high-pressure compaction. This is currently the most mainstream and efficient molding technology.
Features: Fast and uniform sand filling, good compaction effect, high sand mold precision, and easy automation. It can be divided into box-mounted pressurization and non-box-mounted pressurization.
Vertical split mold without box pressurization molding machine (such as the DISA line): Molding, core binding, pouring, and cooling are all carried out on a vertical series production line, with extremely high productivity, suitable for large-scale, medium-level complexity castings (such as brake discs, clamp bodies, etc.).
Horizontal split mold molding machine: It can be divided into core-release molding machine and box-mounted molding machine (often forming an automatic molding line).
5. Static pressure molding machine (air pre-compaction + high-pressure compaction)
Principle: First, blow compressed air into the sand box to initially fluidize the molding sand and fill all parts of the sand box (pre-compaction), then perform multi-contact compaction with a high specific pressure. Feature:
The compactness of the sand mold is extremely high and extremely uniform, with a hardness of over 90.
The demolding accuracy is high, and the casting dimensions are precise, with a smooth surface.
The equipment structure is complex and the investment is large. It is the preferred choice for producing high-quality and complex castings (such as engine blocks and covers of automobiles).
6. Impact Molding Machine
Principle: Utilizing gravitational acceleration (such as quickly falling and impacting after vacuum holding the sand box) or shock waves generated by gas explosion, the sand gains kinetic energy in a very short time and becomes compact.
Features: Fast compaction speed, good uniformity of the sand mold, lower noise than the vibration compaction type. However, the equipment maintenance requirements are higher.
7. Press Molding Machine (mainly used for manufacturing sand cores)
Principle: The core sand is injected into the heated metal core box, and the sand core is formed by the heat-hardening of the thermosetting resin sand. Usually refers to the injection machine (hot core box, cold core box).
Features: Specifically used for manufacturing high-precision and high-strength sand cores.
II. Classification by Sand Mold State
With-box Molding Machine: Uses a fixed sand mold for molding, and after molding, the sand mold together with the sand box is transported and poured. It has good flexibility and is suitable for large and medium-sized castings and molding lines.
Without-box Molding Machine: During molding, a template frame is used, and after the sand mold is made, it forms a solid "sand block" by itself, and there is no need for a sand box for molding. It saves the cost and management of sand boxes and has high productivity. Representative is the vertical split press molding machine.
De-box Molding Machine: During molding, a detachable sand mold (sleeve mold) is used. After molding, the sand mold is removed, and the sand mold is in a compact state similar to without-box. It is a common method for batch production of small castings.
III. Classification by the Direction of the Splitting Surface
Horizontal Splitting Molding Machine: The splitting surface is in the horizontal direction, which conforms to the traditional molding habit. It is convenient to insert the core, and has the widest application range.
Vertical Splitting Molding Machine: The splitting surface is in the vertical direction. The typical representative is the vertical splitting without-box press molding machine. It has high space utilization and is fully automatic and continuous production.
IV. Introduction of Core Functions
Filling Sand: Fill the sand box or template frame with a quantitative amount of sand quickly and evenly.
Compacting: Increase the density of the sand by physical methods (shaking, pressing, airflow, impact, etc.) to obtain sufficient strength and hardness to withstand the pressure of the metal liquid during pouring.
Demolding: After the sand mold is compacted, precisely and smoothly separate the model (mold) from the sand mold to form the cavity. This is the key step to ensure the dimensional accuracy of the casting.
Auxiliary Functions (on automated molding machines):
Sand mold transportation and positioning.
Template replacement (for multi-variety production).
Inserting cores, closing molds. Sand mold ejection and conveying.