Analyze: The characteristics of picking parts by injection manipulator in the installation of injection products in 3C electronic field.

A comprehensive analysis of the technological characteristics of injection molding machine with manipulator in 3C electronics industry

Typical workpieces of 3C products: mobile phone middle frame, shell, battery shell, connector shell, camera bracket, notebook parts, charger shell, keys, etc. Generally thin-walled, high dimensional accuracy, strict appearance requirements, large quantities, mostly small precision plastic parts, which determines the obvious difference between mechanical hand picking and traditional large plastic parts (home appliances, auto parts).

First, the core demand characteristics brought by the product itself

The appearance is free of defects, and scratches, white tops and indentations are strictly prohibited.

3C shell mostly needs oil injection, electroplating, anodizing and laser engraving.

Manipulator clamps can't touch the appearance surface hard, and silica gel suction heads and vacuum suction cups are mainly used, supplemented by mechanical clamping claws;

Pick-up pressure and buffering speed must be adjustable, and rigid impact on plastic parts is prohibited;

Thimble marks and pinch marks are not allowed to stay in the visible area, and many products can only be adsorbed on the inner side.

Plastic parts are thin-walled, easy to deform and have poor rigidity.

Many 3C plastic parts have a wall thickness of 0.6 ~ 1.2 mm, and the temperature of just demoulding is high, so they are prone to warping at high temperature.

Key actions of the manipulator: take it out smoothly and at a constant speed, and avoid pulling at a single point; Some products are put into the jig for shaping/air cooling immediately after being taken out to prevent free cooling deformation.

High dimensional accuracy (±0.03~0.1mm level)

The assembly tolerance of mobile phone structural parts and connector housings is extremely small.

The repeated positioning accuracy of the manipulator is high, so the servo three-axis/five-axis manipulator is generally selected, and the simple pneumatic oblique arm machine is not recommended;

The positions of the placing box, the assembly line and the cooling fixture are consistent and stable, so as to avoid subsequent automatic detection and automatic feeding and material jamming caused by skewed placement.

Small multi-cavity mold is the main part.

3C molds are common: 1×8, 1×16, 1×32 multi-cavity molds, with multiple small parts per mold.

The sucker layout needs to be arranged corresponding to the cavity;

Suck all cavity products synchronously to prevent some from taking and some from missing;

Need to be equipped with leak detection (vacuum pressure detection, photoelectric detection), not to take an alarm, to prevent the product from staying in the mold and pressing.

2. Action and Operation Characteristics of 3C Injection Molding Manipulator

1. The tempo is extremely demanding.

3C injection molding cycle is generally short: 20 ~ 60s, and the competitive production line pursues the extreme beat.

The mainstream scheme of servo traverse manipulator;

Step-by-step speed regulation: buffer at low speed near the mold, move at high speed in the air, and slow down again near the placement position;

Reduce redundant standby actions, optimize waiting sequence, and link with injection molding machine mold opening and ejection signals.

Key differences: The mechanical hand for injection molding large household appliances will reserve buffer time, and the 3C production line will squeeze almost every second.

2. The signal linkage and safety logic are complicated.

Most automatic connection schemes in 3C factory are: mechanical hand picking → putting the assembly line/cooling fixture → automatic gate cutting, inspection and plate setting.

Signal interaction: injection molding machine, manipulator, gate shearing machine, assembly line, photoelectric and vacuum pressure switch are interlocked with each other.

Typical protection logic:

Abnormal vacuum → mold clamping is prohibited;

The product has not been put down → it is forbidden to enter the mold again;

The foreign body and gate residue in the mold are stopped by alarm to prevent the expensive and precise 3C mold from being damaged.

3. The fixture and sucker fixture are highly customized.

Few universal fixtures, almost one set of customized sucker sets:

Pure appearance parts: full vacuum sucker scheme;

Products with gates: sucker suction products+small gripper clamping runner;

Soft rubber, two-color 3C parts: independent vacuum control is needed to prevent the product from being pulled and deformed;

Two-color injection molding 3C shell (PC+TPE) production line, and dual-position manipulator and rotary servo mechanism will be used to complete in-mold sequence transfer.

Three, production management and yield related characteristics

Environmental requirements of dust-free workshop

The middle and high-end 3C production line is in the 10,000-class/100,000-class clean workshop.

The manipulator adopts dust-proof guide rail and dust-free lubricating grease;

Avoid blowing a lot of air into the cylinder to raise dust;

Suction cups should be cleaned regularly to prevent dust from adhering to plastic parts and causing appearance stains.

Strong demand for gate processing automation integration

3C products hardly accept manual gate shearing.

Two mainstream schemes:

① After the manipulator is taken out, it is directly placed in the automatic gate shearing fixture;

(2) The manipulator carries scissors, and the runner is cut off online after taking the piece;

Compared with traditional industries, which often break gates manually, 3C is basically unmanned.

Automatic shunting of defective products

With visual inspection, the manipulator can put good products and bad products in different boxes according to OK/NG signals, and realize automatic sorting.

Fourth, the pain points and difficulties (unique to 3C scene)

Risk of deformation of high-temperature thin-walled parts

The temperature of PC/PC+glass fiber parts just demoulded is high, and the suction is too large to sag and the suction is not enough to fall off; It is necessary to adjust the vacuum threshold, shorten the hanging time, and locate the support cooling as soon as possible.

Transparent parts (lenses, light guide columns) are required to prevent sucker printing.

Ordinary silicone sucker cannot be used, but special sucker is needed to reduce the adsorption area and avoid the optical effective area.

Multi-cavity mode imbalance problem

Individual cavity products stick to the mold, which is prone to local leakage; Must rely on independent vacuum circuit+negative pressure monitoring one by one.

Frequent exchange of money

3C products have fast iteration, and often change molds and products.

It is required to call the manipulator program quickly and disassemble the sucker structure quickly to shorten the downtime of changing models.

V. Solutions

Low-end charger shell, ordinary plastic parts: three-axis servo traverse manipulator, vacuum sucker;

Mobile phone frame, precision structural parts, two-color products: five-axis servo manipulator (with servo rotation);

Ultra-thin shell: vacuum suction is preferred, and hard claws are used with caution;

Large-scale dust-free workshop project: dust-free manipulator+vacuum pressure monitoring+leakage alarm;

summary

The core contradiction of picking parts by 3C electronic injection manipulator is short beat and high efficiency+precise appearance protection+prevention of deformation of thin-walled parts; Different from the traditional injection molding industry, it highly relies on customized vacuum sucker, stable repeated positioning and perfect interlocking detection, and is easy to be connected with the automatic gate cutting, detection and disk setting in the later stage, and at the same time adapts to the production mode of dust-free production, frequent production change and multi-cavity precision mold.