Drop Weight Tear Test Machine

Functions

This type of machine is especially designed for drop-weight tear tests of ferritic steels  

Standards

GB/T 8363, ASTM E436, API RP 5L3, GOST 30456 

Features

1.      SIMENS PLC controls and touch screen provide high reliability and versatility.

2.      Automatic specimen feeding and automatic positing

3.      Frame structure is made of solid steel plate with high stability under impact

4.      Striker is made of high strength steel plate with high impact resistance

5.      Use chain to lift striker with high precision in height

6.      Self-lock design for striker clamping

7.      Full-closed safety shield

8.      Special design tools for support change

Description

This machine is constructed by main frame, striker, striker lifting system, striker release/clamp device, specimen feeding system, damping device, specimen collecting device, guard screen, and control system.

 

Main frame

The bottom plate is made of solid steel plate, mass is up to 2100kg. Anvil is located onto the center of the bottom plate. Impact force onto the frame will rapidly transmit to the ground. As the impact force applies to the center of the main frame which is at the center of the foundation, foundation area is not so big (3mx3m), after long use, foundation will not decline by vibration, and horizontal level of the main frame will not change too.

The main frame is supported by four columns. Each column is divided by upper and lower part. The lower part of the columns is cone-shape cast iron; the upper part is high strength steel pipe. Cone-shape of lower part has higher anti-decline ability than cylinder-shape. Cast iron has stronger vibration resistance and isolation, the vibration caused by impact force will not transmit to the top plate, therefore, the main frame has not apparent vibration for each impact test.

Specimen support and anvil

Anvil is split-type design, separated from support. It is simple to change the anvil after wearing. Anvil radius contacting specimen is R15.5mm, made of 6CrW2Si material, with HRC58~65 hardness after heat treatment. This material is one kind of tool steel, able to bear high speed impact, with high hardness. Various size of spacers are used to satisfy specimens with different thickness ranging 3~10mm, 10-15mm, 15-20mm, 20-25mm, 25-30mm, 30-35mm, 35-40mm, 40~45mm, 45~50mm.

Striker

Striker consists of a few parts, which are made of separately machined steel plate. It features high impact resistance ability. Junction between each part is fixed by pin, jointed by high strength screw bolt. Tup is made of alloy steel 6CrW2Si with good impact resistance, little abrasion, long service life, and simple to change. The weights are separate, easy to change. Connection between weights is alignment pin with reliability.

Striker lifting system

Japanese made chain crane is used for lifting system, featuring light weight, small size, low noise and high stability.

Chain has less elasticity than wire rope, ensuring high accuracy in lifting height, with accuracy up to ±3.5mm.

Striker release/clamp device

It is specially design and will automatically lock after clamping the striker. This device won’t open caused by gravity even when the power is off. It is equipped with approach switch to detect the position. If striker is not clamped, crosshead won’t move. It uses AC electromagnet for release of striker, no need of air supply, easy to mount and operate.

Semi-automatic specimen feeding device

Use motor to feed specimen within 5 seconds, fast, reliable and easy to operate. The frame is one body machined, without welding, with high strength. The frame tightly fits to the support, reducing the force on motor and extending the life of motor.

Damper

As the test standard requires only one drop can tear the specimen, there is big residual energy after impact. Sometimes, the residual energy may reach several thousand or even more than ten thousand joules.  Under low temperature impact test, the residual energy may be much higher. In this case a damping device is necessary and it will affect the service life of the impact machine. We specially design one kind of hydraulic damping device. Its structure especially the damping hole is strictly calculated and proofed after plenty of tests. Single damper can absorb up to ten thousand joules. The whole process is very stable, minimizing the impact to the machine. Both dampers have the same performance, extending the service life of the equipment.

Specimen collecting device

This device uses motor to drive rubber belt for sample collection after impact test. There I protection shield around the belt. After finishing test, broken specimen will drop onto the belt. After finishing each test, the collection device will run automatically and bring the specimen out, which improves the work efficiency and safety of operators.

Safety

Ø  There are full closed guard screen around the main frame to prevent broken specimen from splitting, also prevent operators from entry to the frame inside.

Ø  Guard screen has door limit switch. When the door is open, the machine will lock automatically. Therefore it will avoid wrong operation and guarantee the safety of operator.

Ø  Upper and lower limiter is to protect machine from damage.

Ø  Lifting motor will brake automatically when power-off, to prevent striker from falling.

Ø  Striker clamping hook has signal switch. If this switch has no detection of hook in correct position, lifting system won’t work. Clamping hook has self-lock function, that is, external force can’t release the striker if electromagnet is not activated.

Ø  Two sleeve supports are supplied for maintenance use. When operator need change striker or specimen fixture, sleeve supports can be mounted onto damping cylinder and place striker body onto the supports. This will prevent sudden falling of striker body and protect operator.

Control system

Ø  Control system in this machine provides automatic operations for striker lifting, zero positioning, specimen auto-feeding, impact, and striker clamping, which greatly reduces labor intensity and improves working efficiency and operating safety.

Ø  Simens PLC programmable controller S7-300 series is used for the whole control system. PLC features high stability and reliability and strong anti-interference ability, avoiding any fault operation and improving safety of operators.

Ø  10’ wide-view touch screen is used for terminal operating interface, simple to use. By switching different operation interface, it can perform test or maintenance. Working status monitoring and troubleshooting interface facilitates diagnose.

Ø  Rotary encoder is used for sampling and controlling the height.

Ø  Meanwhile this control system has an alarm function for such errors: specimen is not in the right position, striker is not locked, and guard screen is wrong, striker is not lifted to the correct position.

Ø  Drop height can be input manually, or by inputting impact energy, the system can calculate the height automatically.

Working conditions

Ø  Power supply: 3-phase, 5-line, VAC380V, 20kW; 1-phase 220VAC, 1kW.

Ø  Air supply: 0.4~0.6Mpa, 50L/min.

Ø  Work shop height: >6.5m

Ø  Temperature: 10℃~35℃

Ø  Grounding: resistance 3000㎜Ω.cm, soil resistance temperature 100℃-cm/w.