Servo vibration welding is based on the principle of friction welding. Two plastic weldments that are pressed together, vibrating one of them to make a reciprocating displacement relative to the other, the displacement value can be up to 1.8 mm or 4 mm, the distance between the peak and peak is called the amplitude, and the vibration The frequency is 240 Hz, which generates frictional heat. It’s like rubbing two hands together.
In this process, one of the welded parts is mounted on the fixture of the elevating platform, and the other is placed on the driving fixture of the upper driving plate in the assembled position. The lifting platform moves up and down perpendicular to the vibrating head, and the servo system provides power and controls the pressure. The two parts must be pressed together by the clamping force of the lifting platform, which continues to act on the plastic part during the welding and holding cycle. Under pressure， the vibrating head vibrates and the plastic part is melted after a few seconds or dozens of seconds. This time is called “welding time.” The molten plastic is then cooled and solidified under pressure for a short period, which is called “hold time.” After the “hold time” is over, the lifting platform is lowered and returned to the unloading position (initial position).
Vibration welding machine Important Components
Our big servo vibration welding machine 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 machine. The vibrating head, servo and all transmission machinery are mounted in the frame. A sound proof cover is placed over the plastic vibration friction welding machine to prevent noise generated during vibration and to protect the operator. The front of the soundproof cover has a door that slides and opens 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: 40KW
Frame
The frame of the plastic vibration friction welding machine 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 plastic vibration friction welding machine falls on the ground through four feet with rubber pads. The foot is adjustable. When the machine 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 of the vibration head：
Frequency range：110Hz
Vibration range：0~3.6mm
Drivable fixture weight： 130~160kg
Drive board size： 1400（L）×550（W）mm
Vibration head model：FW-3000
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 rise and drop 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 0.6 MPa.
Safety circuit
The plastic vibration friction welding machine is equipped with the following safety circuits:
- Maintenance door safety
- 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).
- Operator station safety curtain.
- safety door
1 | Safety switch behind the maintenance door |
2 | emergency button |
3 | safety curtain |
4 | safety door |
Vibration head unit
Vibration head: a unit that drives the upper tool to perform linear vibration.
No. | Description |
1 | Tool drive board |
2 | Spring piece |
3 | electromagnet |
4 | Fixed beam |
5 | shock pad |
FAQ
What thermoplastic materials are compatible with vibration welding, and can different resins be welded together?
Vibration 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 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.
What after-sales services does your plastic welding machine manufacturer provide, including training, maintenance, spare parts, and emergency support?
Our after-sales service：
- Training and production guidance
- Inspection, repair and maintenance
- Spare parts management
- Emergency service and repair
- Device update
- Vibration welding Machine and production relocation
What improper vibration plastic welding machine use behaviors must be strictly avoided during daily production?
In the daily production process, some improper use of machine will occur. Here we emphasize again that the following incorrect operations are prohibited:
- Do not store any items on the top of the machine, otherwise the top may collapse, damage the
internal structure of the equipment, and even cause injury to personnel on the site;
- No items are allowed on the soundproof cover in front of the machine safety door, and no one is allowed to lean on or sit on the soundproof cover in front of the safety door. Once the security door is closed, items stored on the front soundproof cover will fall, causing damage to the item and personal injury.
How should operators safely run and shut down vibration welding machine to avoid overload and ensure proper protection?
During the operation：
- The machine must be operated idly, it can be only operated after confirming normal.
- It is forbidden to operate the machine with sickness and overloaded work.
- The operator should not place the body part on the edge or under the workpiece, paying attention to the position of the person.
- Large object processing must be supervised by a special person.
- Do not shield the safety curtain. After the operation：
- The power must be turned off and the distribution box must be closed.
- The working place must be cleaned to keep the machine clean.