Abstract: The present disclosure relates to a device and a system for testing flatness. The device for testing flatness includes a base, a testing platform, and a ranging sensor. The testing platform is assembled on the base. The testing platform includes a supporting structure. The supporting structure is disposed on the side of the testing platform away from the base and is used to support a to-be-tested board. The structure matches the structure of the to-be-tested board. The ranging sensor is disposed on the side of the testing platform away from the base. After the to-be-tested board is placed on the testing platform, the ranging sensor is used to test distances between a number N of to-be-tested positions on the to-be-tested board and the ranging sensor, to obtain N pieces of distance information, and the N pieces of distance information are used to determine the flatness of the to-be-tested board, where N is an integer greater than 2.

Abstract: A cab frame includes a support framework, where the support framework includes a bottom frame, a top frame, and a four-upright-column structure supported between the bottom frame and the top frame; the four-upright-column structure includes two front upright columns and two rear upright columns, and an inner dimension of the cab frame increases along the bottom-to-top direction.

Abstract: A biodegradable Zn—Mg—Bi zinc alloy and a preparation method thereof. The method including: melting magnesium under an inert atmosphere to obtain a magnesium melt; adding bismuth particles to the magnesium melt followed by reaction under stirring and heat preservation treatment to obtain a Mg—Bi alloy melt; allowing the Mg—Bi alloy melt to stand in a furnace; subjecting the Mg—Bi alloy melt to refining, slagging-off, casting and demoulding to obtain Mg-50 wt. % Bi alloy ingot; melting zinc to obtain a zinc melt; adding the Mg-50 wt. % Bi alloy ingot and pure magnesium or pure bismuth followed by heating to a preset temperature, stirring and heat preservation to obtain a Zn—Mg—Bi alloy melt; allowing the Zn—Mg—Bi alloy melt to stand in a furnace followed by refining, slagging-off, casting and demoulding to obtain the biodegradable Zn—Mg—Bi zinc alloy.

Abstract: The present invention discloses an experimental device for cavitation corrosion of liquid metal, comprising a stand, and a vibration device and a lifting and rotating device separately arranged on the stand, wherein a heating device for experimental use is arranged on the vibration device; a furnace lid with a sealing ring is arranged above the heating device; a stirring mechanism is arranged on the furnace lid; the stirring mechanism is connected to a chunk below the furnace lid; a clamp is connected below the chuck, and the clamp is connected to a sample; the furnace lid is connected to the lifting and rotating device; the lifting and rotating device can control the movement of the furnace lid so that the sample is placed in the heating device; the lifting and rotating device, the stirring mechanism, the heating device and the vibration device are connected to a control system.

Abstract: The present invention discloses an experimental device for cavitation corrosion of liquid metal, comprising a stand, and a vibration device and a lifting and rotating device separately arranged on the stand, wherein a heating device for experimental use is arranged on the vibration device; a furnace lid with a sealing ring is arranged above the heating device; a stirring mechanism is arranged on the furnace lid; the stirring mechanism is connected to a chunk below the furnace lid; a clamp is connected below the chuck, and the clamp is connected to a sample; the furnace lid is connected to the lifting and rotating device; the lifting and rotating device can control the movement of the furnace lid so that the sample is placed in the heating device; the lifting and rotating device, the stirring mechanism, the heating device and the vibration device are connected to a control system.