Patent ID: 8884775

Claim:
A belt monitoring device for an injection molding machine, for monitoring abnormality of a plurality of timing belts, each extending between at least one or more driven pulleys provided on one driven shaft and driving pulleys provided on each of rotation shafts of a plurality of rotation driving portions, comprising: a first rotary encoder for detecting a rotation position of a first rotation driving portion; and a second rotary encoder for detecting a rotation position of a second rotation driving portion; a molding machine controller having: deviation calculating means for receiving an encoder pulse outputted from the first and second rotary encoders for determining a deviation between an encoder output value outputted from the first or second rotary encoder and an encoder output value outputted from the second or first rotary encoder; abnormality determining means for comparing said deviation with a threshold value set in advance and for determining that the deviation is the threshold value or more; and abnormality output means for outputting at least a determination result of the abnormality determining means.