METHOD OF DETECTION OF ABNORMALITY OF SQUEEZE PIN AND MOLDING MACHINE

Abstract

A molding machine able to stably detect an abnormality of a squeeze pin, for example, a die cast machine having a squeeze pin able to apply pressure to a melt of a cavity repeatedly performing a molding cycle including a pressing process making the squeeze pin advance and applying pressure to the melt of the cavity in a state where the melt is filled in the cavity and a spray process making the squeeze pin advance and performing at least one of lubrication and cooling of the squeeze pin in the state where the melt is not filled in the cavity, and, in the spray process, detecting a stroke of the squeeze pin and detecting an abnormality of the squeeze pin based on a comparison of the detection result about the stroke and a predetermined reference value.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and features of the present invention will become clearer from the following description of the preferred embodiments given with reference to the attached drawings, wherein:

FIG. 1 is a schematic view of an overall constitution of a die cast machine according to an embodiment of the present invention in an open state,

FIG. 2 is a view of a drive mechanism of a squeeze pin of the die cast machine of FIG. 1,

FIG. 3 is a flow chart showing the operation routine of the die cast machine of FIG. 1,

FIGS. 4A and 4B are views showing an operation state and a method of detection of an abnormality of a squeeze pin of the die cast machine of FIG. 1,

FIGS. 5A and 5B are views showing a modification of the present invention, and

FIGS. 6A and 6B are views showing a modification of the present invention.

Claims

1. A method of detection of an abnormality of a squeeze pin applying pressure to a melt of a cavity of a mold in a molding machine, comprising having said molding machine repeatedly perform a molding cycle including a first step of making said squeeze pin advance and applying pressure to the melt of said cavity in a state where the melt is filled in said cavity and a second step of making said squeeze pin advance and performing at least one of lubrication and cooling of said squeeze pin in a state where the melt are not filled in said cavity and,in said second step, detecting a physical amount indicating an operation state of said squeeze pin and detecting an abnormality of said squeeze pin based on the detection result.

2. A molding machine comprising: a clamping device clamping a fixed mold and a moving mold,an injection device supplying melt into a cavity formed by said fixed mold and moving mold,a squeeze pin able to advance or retract to/from said cavity,a fluid pressure cylinder having a piston fixed to said squeeze pin and driving said squeeze pin,a fluid pressure circuit controlling the flow of a working fluid supplied to a rod side cylinder chamber and a head side cylinder chamber divided by said piston of said fluid pressure cylinder,a control device configured to control operations of said clamping device, said injection device, and said fluid pressure circuit, anda sensor detecting a physical amount indicating the operation state of said squeeze pin, whereinsaid control devicecontrols operations of said clamping device, said injection device, and said fluid pressure circuit so as to repeat a molding cycle including an injection process injecting a melt by said injection device into a cavity of said fixed mold and said moving mold clamped by said clamping device, an applying pressure process making said squeeze pin advance into said cavity in which a melt is filled by the injection and applying pressure to the melt, carrying out process opening the molds by said clamping device after the pressed melt is solidified and carrying out a molded article from said cavity, and a lubricating and cooling process making said squeeze pin advance and performing at least one of the lubrication and cooling of said squeeze pin before said injection process or after said carrying out process andjudges presence of any abnormality of said squeeze pin based on a comparison of a physical amount detected by said sensor in said lubricating and cooling process and a predetermined reference value.

3. A molding machine as set forth in claim 2, wherein said sensor detects a stroke of said squeeze pin, andsaid control device controls the operation of said fluid pressure circuit so that pressurized oil having a predetermined pressure is supplied into said head side cylinder chamber in said lubricating and cooling process and judges that an abnormality occurs in said squeeze pin when said stroke at the time said squeeze pin stops is smaller than the reference stroke set corresponding to said predetermined pressure.

4. A molding machine as set forth in claim 2, wherein said sensor includes a stroke sensor detecting the stroke of said squeeze pin and a pressure sensor detecting the fluid pressure of said fluid pressure cylinder, andsaid control device controls the operation of said fluid pressure circuit so that pressurized oil having a constant pressure and flow is supplied into said head side cylinder chamber in said lubricating and cooling process and judges that an abnormality occurs in said squeeze pin when the pressure detected by said pressure sensor exceeds the predetermined reference pressure before the stroke detected by the stroke sensor reaches the predetermined reference stroke.