Failure diagnostic apparatus for ball screw device

A failure diagnostic apparatus which works to detect a failure in operation of a ball screw conveyer which uses linear motion into which rotational motion of a ball screw is translated to convey an object, comprising:

• a contact member which is arranged in contact with a bearing which retains an end of the ball screw or with the ball screw;
• an expandable/contractable member which expands in response to displacement of the contact member to absorb heat or contracts in response to the displacement of the contact member to produce heat;
• a heat flux sensor to which heat of the expandable/contractable member is transmitted and includes an insulating substrate, first layer-to-layer connecting members, second layer-to-layer connecting members, and conductive patterns, the insulating substrate being made of thermoplastic resin and having formed therein first via holes and second via holes which pass through a thickness of the insulating substrate and are arranged alternately, the first layer-to-layer connecting members being disposed in the first via holes, the second layer-to-layer connecting members being made from metallic material different from that of the first layer-to-layer connecting members and disposed in the second via holes, the conductive patterns alternately connecting the first layer-to-layer connecting members and the second layer-to-layer connecting members together;
• and
• a malfunction detector which is electrically connected to the heat flux sensor and works to detect a failure in operation of the ball screw conveyer using an output from the heat flux sensor.