Vibration welding machines and equipment Introduction
Vibration friction welding is a newly developed welding technology. It can weld a wide variety of thermoplastic parts without implementation of additional connectors or self-consumable materials such as adhesives, solvents, etc., and only the plastic parts themselves are welded together by the welding process.
Almost all thermoplastic materials can be welded by vibration friction welding technology, whether they are injection molded, extruded, foamed, or thermoformed. This joining method is particularly advantageous for crystalline resins such as acetal, nylon, thermoplastic resins, polyethylene and polypropylene. Other materials, including cellulose, thermoplastic and synthetic rubbers, fillers, reinforced resins, and those materials with hygroscopic properties are also easily welded.
In any case, the two welded parts must be the same thermoplastic resin or compatible resin. Most thermoplastic resins are well welded to the same materials as themselves, but some different materials can be also welded together, for example: polycarbonate to polypropylene, ABS to polypropylene. However, in general, different materials cannot be well welded.
The safety protection measures of this machine
* Three-color warning light: The red light is on when the Vibration welding machines and equipment is running, and the green light is on during normal operation. The yellow light is on when it is paused or not working.
* Emergency stop switch: Press the emergency stop switch in any emergency, which is, stop the operation.
* Safety curtain: When working, any item (including any part of the body) enters the inside of the device, the Vibration welding machines and equipment immediately alarms and stops running.
Important Components
servo Vibration welding machines and equipment consists of 9 main parts:
- Electrical control device
- Vibration source
- Frame
- Vibration Head
- Servo System
- Transmission System
- Soundproof Cover
- Base seat
- Pneumatic system
Among them, the electrical control device and the vibration source are installed in the electric control cabinet on the right side of the Vibration welding machines and equipment. The vibration head, servo and all transmission machinery are mounted in the frame. A sound proof cover is placed over the machine to prevent noise generated during vibration and to protect the operator. The front of the soundproof cover has a door that sliding opens and closes in the vertical direction. There are two opposite doors on the back of the soundproof cover, allowing maintenance personnel to enter the inside of the vibration welding machine for maintenance.
Electrical control unit
The electrical control unit consists of a programmable controller (PC), control relay, transformer and touch screen, and the user operates the machine on the touch screen. The PC controls the start and stop of the vibration source, the sequential operation of the servo system, and all machine functions.
Vibration power supply
The vibration power supply mainly supplies electrical current to the drive coil of the vibrating head, causing the vibrating head to vibrate, so it is called a vibrating power source.
After the initial start-up and each time a new fixture is replaced, the operator must adjust the output frequency and output voltage of the vibrating power supply through the touch screen. The output frequency is used to tune the resonant frequency of the vibrating head, and the output voltage is used to tune the corresponding amplitude of the vibrating head.
There is a closed loop between the power supply and the induction coil of the vibrating head and the magnet for feedback of the amplitude of the vibration. Main performance parameters of the electrical part：
P/S input voltage：460VAC
P/S control voltage： 24VDC Power consumption： 37Kw
Frame
The frame of the Vibration welding machines and equipment is welded from a variety of structural steels. Except for the electric control cabinet, all the other mechanical, pneumatic and other parts are installed on the frame.
Due to complex affect from vibrating head’s horizontal alternating vibration load and the vertical tensile load which comes from the hydraulic system pressing the workpiece by lifting platform，the frame must have sufficient strength and overall stiffness.
The frame of the Vibration welding machines and equipment falls on the ground through four feet with rubber pads. The foot is adjustable. When the Vibration welding machines and equipment is installed, the height and level of the frame need to be adjusted so that the upper surface of the working platform achieves the required level accuracy (≤0.05mm/1000mm).
Vibration head
The vibration head converts AC power into a bidirectional linear motion—vibration. It is mounted on a high-strength rubber mat on the machine frame which separates the vibration of the vibration head from the stationary frame.
The vibration head consists of a large cast iron frame, a spring, a set of drive assemblies and two drive coils. The springs are cantilevered beam springs that are fabricated from a single piece of high strength alloy steel. The top of each spring is screwed onto the cast iron frame. At the other end, the bottom of the spring is used to suspend the vibrating element (drive assembles and drive fixture).
The vibration head is based on the resonance of the spring assembly, so the motion of the vibration head is closely related to the pendulum motion. In the spring assembly system, one spring is fixed at one end and the other end is connected to the assembly. If the system is tapped, the system will vibrate, and the frequency of the vibration is a function of spring mass and spring rate. This spring rate is called the spring constant. This frequency is called the natural or resonant frequency of the system. In order to let the system does work, electrical energy must be applied alternately to the solenoid. If the frequency of the applied electrical energy matches the natural frequency of the system, its energy consumption is minimal.
Main performance parameters
Frequency range：210~250Hz
Vibration range：0.6~1.8mm
Drivable fixture weight： 35~70kg
Drive board size： 1000（L）×550（w）mm
Vibration head model：JF-2000
servo system
The servo system consists of a servo motor and a servo controller.
Its main performance parameters：
Main motor rated power： 7.1KW
Rated frequency：215Hz
Rated speed： 3225r/min
Maximum output current： 15.6A
Maximum table pressure available：2.5KN
Transmission system
The transmission system consists of a lifting platform, two guide shafts, four linear bearings and a tight chain sprocket. The lifting platform is driven by a servo motor and performs vertical ascending and descending movement along the guide shaft. During welding, the lower tool is mounted on the lifting platform, and the lower fixture for clamping the plastic part is mounted on the lower tool. The moving position of the lifting platform is determined by the displacement size.
soundproof cover
The outer casing of the soundproof cover is made of steel plate, and the inner wall is lined with sound absorbing material.
An active sliding door, also called a safety door, will be installed on the front of the soundproof cover. The door is mounted on the soundproof cover with four linear guides and two vertically mounted guide shafts. The up and down stroke is driven by a servo motor. The safety door is closed during welding. For non-welding time, the safety door is opened to remove the welded plastic parts. The inner wall of the safety door is also lined with a sound absorbing panel, and a sealing material is arranged between the safety door and the soundproof cover.
Pneumatic system
The pneumatic system consists of an on-off valve (discharge valve), a pneumatic five-piece, a three-position five-way valve, a one-way throttle valve, a muffler, and a cylinder. The pneumatic system is mainly used to drive the movement of the mold fixture cylinder.
The air source of the pneumatic system is provided by the user and the pressure is 0.6MPa.
Safety and protection device
Safety devices are part of the normal equipment state of the Vibration welding machines and equipment. They are used to protect personal life and health and safety. If the safety device is disabled, the careless behavior is fault-free.
Safety circuit
The device is equipped with the following safety circuits:
1.Maintenance door safety switch.
2.Operator station’s emergency stop button, which is distributed under the operation panel and the man-machine interface operation panel (on the side of the electrical box).
3.Operator station safety curtain
4.safety door
Transmission unit
Auxiliary sliding table: the auxiliary sliding table is used to carry and drive the hot tool for up and down movement.
Serial number | Description |
1 | Up and down vertical lifting cylinder |
2 | Up and down vertical lifting table |
3 | Left and right guide rail |
Vibration head unit
Vibration head: a unit that drives the upper tool to perform linear vibration
Serial number | Description |
1 | Tool drive board |
2 | Spring piece |
3 | electromagnet |
4 | Fixed beam |
5 | shock pad |
Supply and exhaust interface
Electrical connections:
*A connection error can cause the device to be unintentionally activated or unable to control the device while it is running.
*Confusing wiring may affect the life of the equipment.
*Wiring errors can affect the life of electrical components.
Compressed air connection:
*Check that the compressed air hose is connected to the maintenance unit and that the position is fixed.
*The manual on/off valve must be open for operation.
*Check that the working pressure of the pressure display is 6 bar.
Manually open valve (compressed air supply)
The beating hose hurts the eyes!
The pressure storage device is potentially dangerous (sometimes in emergency shutdown)
*Pneumatic equipment must be replaced with no pressure before operation (exhaust Danger
is automatically done when the air supply valve is closed).
→The compressed air supply to the unit is turned on or off by manually-turning valve.
The compressed air supplied to the start control device assembly is processed by the maintenance unit, the pressure in the supply line adjusted to an operating pressure of approximately 6 bar (nominal pressure), accumulated condensate will deposit.
Tuning of the vibration head
The vibration head has different resonant frequencies for different fixtures. This resonant frequency is determined by the spring stiffness of the vibration head and the weight of the components (including the upper fixture) attached to the spring . Only at the resonant frequency, the input drive energy is minimal.
There are two ways to tune the vibration head, automatic and manual.
Caution！
- Do not test the vibration head when the upper fixture plate and upper fixture are not installed.
- Tuning is critical when changing fixtures. At the very least, automatically tune before each shift or when creating suspicious problems and changing fixtures.
Automatic tuning of the vibration head
The automatic tuning of the vibration head refers to determining the range of the vibration frequency of the vibration head equipped with the fixture at different amplitudes to determine a suitable resonant frequency.
First press the manual mode button on the main menu (start screen interface). The manual interface appears on the touch panel. Start the servo system in normal operation and keep the lifting platform in the lowest position.
Press the auto tuning button again and the auto tune screen will appear on the touch screen. Press the FM start button on the interface to start auto tuning, the auto tuning indicator lights up, and the vibration sound appears.
The time required for auto-tuning is approximately 90 seconds. After finding the appropriate resonant frequency, the auto-tuning indicator light turns off. Press the set frequency button to store the frequency.
During the tuning process, if the fault light is on, press the clear fault key. After the fault light is turned off, press the FM start key again for automatic tuning again.