Manufacturing apparatus and manufacturing method of molded products
A manufacturing apparatus includes an injection cylinder to which molten resin is supplied and which is configured to inject molten resin, an injection plunger disposed such that the injection plunger fits in the injection cylinder and moves in a first direction and a second direction opposite to the first direction, a pressing member configured to be able to be separated from the injection plunger and press the injection plunger for moving the injection plunger toward the first direction, and a sensor configured to detect contact and/or separation between the injection plunger and the pressing member. In a state where the pressing member is separated from the injection plunger, molten resin supplied into the injection cylinder presses the injection plunger to move the injection plunger in the second direction, and contact between the injection plunger and the pressing member is detected by the sensor.
1 . A manufacturing apparatus comprising:
an injection cylinder to which molten resin is supplied and which is configured to inject molten resin;
an injection plunger disposed such that the injection plunger fits in the injection cylinder and moves in a first direction and a second direction opposite to the first direction;
a pressing member configured to be able to be separated from the injection plunger and press the injection plunger for moving the injection plunger toward the first direction;
a driving source configured to drive the pressing member in the first direction and the second direction;
a control portion configured to control the driving source; and
a sensor configured to detect contact and/or separation between the injection plunger and the pressing member,
wherein the injection cylinder includes a base body configured to contain molten resin, and a sleeve configured to be detachably attached to the base body,
wherein the injection plunger is configured to be inserted into an inner portion of the base body through an opening portion formed in the sleeve and slide on the sleeve,
wherein the control portion is configured to control the driving source to move the pressing member to a first position when metering molten resin supplied into the injection cylinder in a state where the pressing member is separated from the injection plunger,
wherein, in a state where the pressing member is separated from the injection plunger, molten resin supplied into the injection cylinder presses the injection plunger to move the injection plunger in the second direction, and
wherein a contact between the injection plunger and the pressing member that is located at the first position is formed by the moving of the injection plunger in the second direction and is detected by the sensor.
2 . The manufacturing apparatus according to claim 1 , wherein the control portion is configured to control the driving source for retracting the pressing member to a second position that is retracted from the first position toward the second direction.
3 . The manufacturing apparatus according to claim 2 , wherein the injection plunger is moved toward the second direction by molten resin supplied into the injection cylinder pressing the injection plunger in a state where the pressing member is in the second position.
4 . A method for manufacturing a molded product using the manufacturing apparatus according to claim 3 , the method comprising:
injecting molten resin in the injection cylinder into a cavity of a mold by controlling, by the control portion, the driving source so as to move the pressing member from the second position to a third position forward of the first position in the first direction.
5 . The manufacturing apparatus according to claim 1 , wherein at least a front-end portion of the injection plunger is located in an inner portion of the injection cylinder.
6 . The manufacturing apparatus according to claim 1 , wherein a whole of the injection plunger is located in an inner portion of the injection cylinder.
7 . The manufacturing apparatus according to claim 1 , wherein at least one of a first portion of the pressing member that faces the injection plunger or a second portion of the injection plunger that faces the pressing member is formed spherical.
8 . The manufacturing apparatus according to claim 1 , wherein the injection cylinder includes a supply inlet to which molten resin is supplied, and
wherein the manufacturing apparatus further includes a valve configured to prevent molten resin from flowing from the supply inlet toward an outside of the injection cylinder.
9 . The manufacturing apparatus according to claim 1 , wherein the injection cylinder includes an injection outlet from which molten resin is discharged, and
wherein the manufacturing apparatus further includes a valve configured to prevent molten resin from flowing from the injection outlet toward an outside of the injection cylinder.
10 . The manufacturing apparatus according to claim 1 , wherein the control portion is configured to determine that metering of molten resin is completed, by determining that a movement of the injection plunger is prevented by the pressing member that is located at the first position.
11 . A manufacturing method of a molded product, comprising supplying molten resin in the manufacturing apparatus according to claim 1 and molding the molded product.
12 . The manufacturing apparatus according to claim 1 , wherein a difference between an inner diameter of the sleeve and a diameter of the injection plunger is 2 μm to 50 μm.
13 . The manufacturing apparatus according to claim 1 , wherein a back-end portion of the injection plunger is located outside the injection cylinder.
14 . The manufacturing apparatus according to claim 1 , wherein an area of a portion of the injection plunger that slides on the sleeve is larger than an area of a portion of the sleeve that slides on the injection plunger.
15 . The manufacturing apparatus according to claim 1 , wherein a fit length of a fit portion between the sleeve and the injection plunger is larger than a diameter of the injection plunger.
16 . The manufacturing apparatus according to claim 1 , wherein a fit length of a fit portion between the sleeve and the injection plunger is 103% to 270% of a diameter of the injection plunger.
17 . The manufacturing apparatus according to claim 1 , wherein an inner diameter of the sleeve is smaller than an inner diameter of the base body.
18 . The manufacturing apparatus according to claim 1 , wherein an inner diameter of the sleeve is:
(i) 99.0% to less than 100.0% of an inner diameter of the base body; and/or
(ii) smaller than the inner diameter of the base body by 0.01 mm to 0.1 mm.
19 . The manufacturing apparatus according to claim 1 , wherein a step between the sleeve and the base body is smaller than a difference between a diameter of the injection plunger and an inner diameter of the base body.
20 . The manufacturing apparatus according to claim 1 , wherein the pressing member is configured to be separated from the injection cylinder.