Dear friends of bricks,
I proudly present you my LEGO TECHNIC model of an injection molding machine (SGM).
Whether LEGO bricks, garbage cans, pens, car parts, ... all are manufactured in SGM's. An SGM conveys plastic granulate, heats it until it has a creamy consistency, then pumps it under very high pressure into the mold where it hardens and has taken on the desired shape. Finally, the mold is opened and the component is pushed out of the mold by means of ejector pins. Color requests and material properties can be set via the raw material. Depending on the product, removal takes place by ejection or by means of a removal robot.
The basic modular structure of my creation is based on reality. In addition to the SGM, I have designed a transport and discharge module (TAM), the combination allows, as in real life, automated series production. The color design of the assemblies serves to distinguish them and to understand the functional principle.
SGM-2000 / The injection molding machine:
The model consists of four main assemblies, the base frame, the fixed side, the moving side and the housing. All main assemblies can be easily connected or disconnected.
The base frame contains the feet, the support areas and attachment points of the other assemblies, an upper bracket that can be folded on both sides, the guide rails with stop (for ejector package) of the moving side and the swing-and-slide door mechanism.
The fixed side consists of several modules. The frame holds the modules in position, the quickly exchangeable fixed part of the tool (mold) lies away from the front, the filling chamber sits in the middle and the drive with actuator (spindle) and piston sits at the rear. A rotational direction splitter is installed below the drive, which supplies the raw material supply with rotation via a PTO connection. The raw material supply is free-standing and can be easily coupled using PEG. Due to the splitter, only backward movements of the piston into a rotation of the raw material eggs are allowed (in real life is also not permanently conveyed).
The fixed side is fixed with the upper brackets of the base frame and with two bolts.
The moving side also consists of several modules. The frame has a rotatable locking bolt at the top and bottom with which the moving tool part (shape) can be fixed from the front. Using laterally mounted fixable levers, the tool can be quickly fixed or loosened for tool change. The drive is firmly connected to the frame via the piston rods of the two actuators.
The drive of the moving side is attached to the base frame with two bolts, the moving part is guided over rails. The upper brackets of the base frame fix the moving part.
The enclosure is also multi-part. The side panels are attached to the base frame via the door-tube frame, the front and rear sashes are held in position by quick-release fasteners. The upper enclosure is divided into three parts and can be pushed away, it can also be quickly dismantled via quick-release fasteners. A single segment of the upper enclosure holds the small side wings in position, it can be attached via a spreading mechanism. The drive of the fixed side also has a veneer with quick-release fastener, it is two-piece with the lattice door attached to one.
Of course, the stones are not cast, they are extracted. In a vertical shaft, the steep slopes lie on top of each other. The lower part of the chute is in the fixed part of the tool, the upper part protrudes upwards - an interface. Here you can insert the magazine and drop the stones into the shaft. Optionally, you can set up a small direct attachment (insertion), here you can manually feed the machine.
In the lower part there is space for 10 stones (or 5 for 2x4 and 1x2 (2x)). The interjection looks more elegant, which is why it is mainly depicted in the video. The long magazines can also be opened at the rear end and refed manually, or they can be filled with a filling aid (= funnel, not shown because unspectacular).
The stones are now on top of each other. The lowest stone is pushed forward by a slider (instead of liquid as in reality, here solid). When the tool is closed, the stone is pushed against the moving side, directly into a 1x2 technology brick to which it connects. The tool opens and pulls the stone out of the mold. At a certain point, the moving side moves to a stop, the spring-loaded movable slider (ejector) in the tool stops while the rest continues. The stone is ejected (repelled / separated from the mold).
TAM-2 / Transport and Discharge Module:
The TAM consists of three main assemblies. The most important is the conveyor mechanism, after several trials and more compact designs, I guided the chain with only one gear, the drive wheel below. Two long beams guide the chain, the deflection takes place through the beam front side. A loop below serves to engage the drive gear and at the same time acts as chain tensioning.
The drive unit can be easily coupled to the conveyor belt. The gearbox also has a direction of rotation splitter, so a drive (via the direction of rotation) can either move the conveyor belt or operate the discharge-swivel mechanism. The cables of the drive are connected to the cables of the color sensor, which can be easily fixed to the conveyor belt in a holder.
Finally, the last assembly of the TAM, the safety fence - a requirement of 2006/42/EC (Machinery Directive). It can be dismantled or assembled quickly and easily.
How it works:
The stone falls from the SGM onto the conveyor belt, the SGM sends a transfer signal to the TAM which starts the conveyor belt. If the color sensor detects a component, it is measured (length) and the color is determined, at the same time the TAM gives feedback to the SGM that the component has arrived. If no part arrives in the detection time, the TAM stops and the SGM follows a margin call process - if this still fails (e.g. magazine empty) the system goes into malfunction.
Back to the recognized stone. If this is blue, the belt conveys the stone against the discharge slide into the OK stacking box. If it is not blue (fun fact: with ancient stones the blue is probably not blue enough, they are consistently sorted out), the discharge slide adjusts and the stone is thrown into the non-OK stacking box.
It is controlled via a MINDSTORMS hub. In addition, lighting is attached to the hub, which can be coupled to the TAM to supply the SGM interior and TAM ejection zone with light.
Tools / tool change:
A machine does not only have one shape, it has many to be able to adapt the production quickly to the demand. A tool change is also necessary for maintenance / servicing (e.g. wear, cleaning, etc). The machine should go through because of the cost. The possibility to change tools I have provided, there are four tools in my selection (1x6, 1x4, 2x4 and (2x) 1x2). Thus, four products can be simulated, one of them as a multiple tool (1x2).