JP4467079B2 - Toggle mold clamping device - Google Patents

Description

  The present invention relates to a technique for improving a toggle type mold clamping device provided in an injection molding machine.

The injection molding machine has a basic operation of an injection process in which high-pressure resin or metal is injected into a mold cavity. In the injection process, the mold is prevented from opening by clamping the mold with a mold clamping device.
As the mold clamping device, there are known a cylinder type mold clamping device that directly clamps the die with a hydraulic cylinder or an electric cylinder, and a toggle type mold clamping device that clamps the die by extending a bent toggle link with the force of the cylinder. ing.

The toggle type mold clamping device has an advantage that a large mold clamping force can be generated with a small cylinder by skillfully utilizing the principle of the lever.
In order to make the toggle link bendable, a connecting portion structure is adopted in which a bush is provided at the end of one toggle link, a pin is provided at the end of the other toggle link, and this pin is fitted to the bush. .

Since the pin can rotate relative to the bush, the toggle link can be bent. At this time, since slip occurs between the bush and the pin, it is necessary to lubricate.
A technique in which grease lubrication and a solid lubricant are employed for lubrication between the bush and the pin has been proposed (see, for example, Patent Document 1).
Japanese Examined Patent Publication No. 6-65429 (FIGS. 3 and 4)

Patent document 1 is demonstrated based on the following figure.
FIG. 7 is a diagram for explaining a basic configuration of a conventional technique.
In (a), a toggle type mold clamping device 100 is arranged opposite to a machine base 101 and connected by a tie bar 102, 102 with a fixed plate 103 and a pressure plate 104, and between the fixed plate 103 and the pressure plate 104. And a toggle mechanism 110 that is transferred to the movable platen 105 and the pressure receiving plate 104 in order to push the movable platen 105 toward the fixed platen 103.

  The toggle mechanism 110 includes a first fixed arm 111 extending from the pressure platen 104, a second fixed arm 112 extending from the movable platen 105, and a first rotation connected to the first fixed arm 111 via a pin 113 and a bush 114. A first rotating arm 115, a second rotating arm 116 having one end connected to the first rotating arm 115 and the other end connected to the second fixed arm 111 via the pin 113 and the bush 114; It comprises a cylinder 117 that bends the moving arms 115 and 116 in the front and back direction of the drawing.

  When the fixed mold 118 is attached to the fixed platen 103 and the movable mold 119 is attached to the movable platen 105, the first and second rotating arms 115 and 116 are extended by the action of the cylinder 117. 118 and 119 are clamped.

(B) is a sectional view taken along the line bb of (a). A bush 114 is attached to the second fixed arm 112, and a pin 113 is inserted into the bush 114. In the bush 114, 12 solid lubricants 121 (360 to 30% of the ratio of the lubricant to the inner surface area of the bush 114) are embedded per 360 ° of the circumference. Further, the pin 113 is provided with a peripheral groove 123 on the outer peripheral surface, and grease is replenished through a horizontal oil supply hole 124 penetrating therethrough.
Therefore, the bush 114 and the pin 113 are lubricated with the grease and the solid lubricant 121.

However, it has been found that the structure disclosed in Patent Document 1 has the following problems.
When a solid lubricant is subjected to a frictional force, it is exfoliated but becomes a powder. This powder accumulates in the circumferential groove 123 and the horizontal oil supply hole 124 which are concave portions. As the accumulation proceeds, the opening area of the horizontal oil supply hole 124 becomes small, and the grease supply becomes insufficient. As a result, there arises a problem that the wear of the bush 114 and the pin 113 becomes severe.

  An object of the present invention is to provide a structure capable of continuing good grease supply in a toggle mechanism in which lubrication is performed by using grease and a solid lubricant in combination.

  The invention according to claim 1 is a stationary platen and a pressure receiving plate which are arranged opposite to each other on a machine base and are connected by a tie bar, a movable platen movably provided between the fixed platen and the pressure receiving plate, and the movable platen. A toggle mechanism that passes between the movable platen and the pressure platen to push out the platen to the fixed platen. The toggle mechanism includes a bush at the connecting portion, a pin that is rotatably inserted into the bush, and a lubricating surface of the pin. In a toggle type mold clamping apparatus comprising a grease supply means for feeding grease to the toggle type mold clamping apparatus, the portion of the bush that is pressed by the pin during mold clamping of the toggle type mold clamping apparatus is referred to as a pressure receiving surface during operation. When the portion of the bush that is not sometimes pressed by the pin is referred to as a non-pressure-receiving surface during operation, the bush does not include a solid lubricant on the non-pressure-receiving surface during operation. Characterized in that it comprises a body lubricant.

  The invention according to claim 2 is characterized in that the pressure-receiving surface at the time of operation is set in a range of 120 ° to 180 ° in one rotation of 360 °.

  In the invention according to claim 3, the pin is provided with a quenching layer and a plating layer on the surface by performing electroless composite plating after induction hardening.

  In the invention according to claim 1, the pressure receiving surface during operation and the non-pressure receiving surface during operation are set in one bush, and the solid lubricant is disposed only on the pressure receiving surface during operation. As a result, the amount of solid lubricant can be halved. Since the wear amount of the solid lubricant is considered to be approximately proportional to the amount of the solid lubricant, if the amount of the solid lubricant is halved, the amount of powder generated by wear is also halved. As a result, it is possible to greatly increase the time until the filler opening is closed, and to greatly extend the operating time of the toggle mechanism.

  In the invention which concerns on Claim 2, the pressure receiving surface at the time of the action | operation of a bush was set to the range of 120 degrees-180 degrees among 360 degrees of 1 round. If the angle is set to 120 ° or more, the moving range of the toggle link can be sufficiently covered. Moreover, if it sets to 180 degrees or less, the waste of a solid lubricant can be avoided.

  In the invention which concerns on Claim 3, a quenching layer and a plating layer are provided in the surface of a pin. Since the pins are baked, the surface hardness can be increased. Further, since the plating layer is composed of a plurality of layers, there are fine gaps, and solid lubricant powder can be accommodated. As a result, the amount of solid lubricant powder reaching the grease supply hole can be reduced.

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.
In addition, in a bush and the pin inserted in this bush, both a bush and a pin may rotate, and only one may rotate. Therefore, in the embodiment, for convenience, the bush is stationary and the pin rotates.

  FIG. 1 is a side view of a toggle type mold clamping device according to the present invention. A toggle type mold clamping device 10 is arranged on a machine base 11 so as to be opposed to each other and connected by tie bars 12 and 12 and a pressure receiving plate. 14, a movable platen 15 movably provided between the fixed platen 13 and the pressure platen 14, and a toggle passed between the movable platen 15 and the pressure platen 14 in order to push the movable platen 15 toward the fixed platen 13. Mechanism 20.

  The toggle mechanism 20 has a first fixed link 21 extending from the pressure platen 14, a second fixed link 22 extending from the movable platen 15, a steel pin 23, and a high-strength brass bush 24. A first rotary link 25 connected to the link 11, a second rotary link 26 having one end connected to the first rotary link 25 and the other end connected to the second fixed link 22 via the pin 23 and the bush 24. And a drive link 27 that bends the first rotation link 25 in the vertical direction of the drawing, a nut 28 that moves left and right in the drawing to rotate the drive link 27, and a ball screw 29 that is screwed into the nut 28. .

  A fixed mold 31 is attached to the fixed platen 13 and a movable mold 32 is attached to the movable platen 15. Then, the ball screw 29 is turned to move the nut 28 to the position shown in the figure. The drive link 27 pushes up the first rotation link 25 so that the first and second rotation links 25 and 26 are substantially in a straight line. The molds 31 and 32 are clamped by bringing the first and second rotation links 25 and 26 into the extended state.

  FIG. 2 is an enlarged view of two parts in FIG. 1. In the first rotation link 25, a bush 34 (which is the same as reference numeral 24 in FIG. A new code is attached to the movable board boss 25R on the right side of the figure, and the pin 35 (same as the code 23 in FIG. 1 is used, but a new code is added to distinguish the position). The same shall apply hereinafter. In the second rotation link 26, the bush 36 is fitted to the pressure receiving plate side boss 26L on the left side of the drawing, and the bush 37 is also fitted to the movable plate side boss 26R on the right side of the drawing. Then, a pin 38 is inserted into the bush 37.

The bush 34 is fitted to the boss 25L so that the pressure receiving surface 41 is in the right side of the drawing, and the bush 36 is also fitted to the boss 26L so that the pressure receiving surface 41 is in the right side of the drawing. Is engaged with the boss 26R so that the pressure-receiving surface 41 during operation is on the left side of the figure.
In addition, the bushes 42 and 43 are fitted to both ends of the drive link 27 with the pressure receiving surfaces 41 and 41 in operation facing the positions shown in the drawing.

  Reference numeral 44 denotes a tube joint for supplying the grease fed through the grease tube 45 to the pins 35, 38 and the like. The grease tube 45 and the tube joint 44 constitute a grease supply means. The tube joint is more preferably a rotary joint having a rotation function.

  3 is an enlarged cross-sectional view of a part 3 of FIG. 2. The pin 38 is provided with a central hole 47 and a radial hole 48 extending from the central hole 47 to the outer peripheral surface. The bush 37 is provided with a plurality of solid lubricants 49 having a columnar shape mainly composed of graphite. One end of the solid lubricant 49 is in contact with the pin 38.

  The plurality of solid lubricants 49 are provided only on the pressure receiving surface 41 during operation, and are not provided on the non-pressure receiving surface 46 during operation. The pressure receiving surface 41 at the time of operation is set to 120 ° out of one rotation of 360 °. That is, the fan-shaped central angle θ drawn around the axial center of the pin 38 is set to 120 °. The sum of the pressure receiving surface 41 at the time of operation and the non-pressure receiving surface 46 at the time of operation forms a peripheral surface of one round (360 °). The angle of the non-pressure-receiving surface 46 during operation is 240 ° obtained by subtracting 120 ° from 360 °.

  The grease supplied from the central hole 47 of the pin 38 flows through the radial hole 48, flows through the annular groove 51 indicated by the broken line, and then fills the two axial grooves 52, 52 extending in the axial direction. When the pin 38 and the bush 37 rotate relative to each other, the grease enters between the pin 38 and the bush 37 and maintains the lubrication state.

Next, the heat treatment and plating treatment of the pin 38 will be described.
FIG. 4 is an explanatory diagram of heat treatment and plating treatment according to the present invention.
In (a), the pin 38 is preferably a round bar of chromium molybdenum steel (SCM440). After the center hole 47 and the radiation hole 48 are provided by machining, the high frequency coil 53 performs high frequency heating.
While the surface of the pin 38 is red, it is rapidly cooled by being immersed in water or oil. The cooled pin 38 is heated to a tempering temperature to perform a tempering process.
As shown in (b), a hardened layer 54 (more precisely, a hardened and tempered layer) is formed on the outer shell of the pin 38. The quenching layer 54 has the same meaning as the quenching depth, but the name of the quenching layer is used in consideration of the plating layer described later.

Next, in (c), the pin 38 is immersed in the plating solution 56 of the electroless plating tank 55. The plating solution 56 is preferably a composite plating solution made of nickel-phosphorus-silicon carbide (Ni-P-SiC) or nickel-boron-silicon carbide (Ni-B-SiC).
As shown in (d), the hardened layer 54 could be formed on the outer shell of the pin 38, and the plated layer 57 could be formed on the hardened layer 54.

  The hardened layer 54 can increase the hardness of the pin 38. Moreover, since the plating layer 57 is composed of a plurality of layers, there is a fine gap, and the powder of the solid lubricant can be accommodated.

Next, the operation of the toggle mechanism 20 having the above configuration will be described.
In FIG. 3, at the time of mold clamping, the pin 38 strongly pushes the bush 37 as indicated by the white arrow. Basically, the pin 38 and the bush 37 are in contact with each other by a single line extending in the front and back direction of the drawing. However, since the bush 37 is elastically deformed, the contact surface increases, and it is estimated that the contact is made at about 30 ° inside the 120 ° sector. Even if the pin 38 rotates relative to several tens of degrees, there is no concern that the contact surface will deviate from the 120 ° sector.

  That is, the operating pressure receiving surface 41 indicated by the angle θ of the bush 37 is lubricated by the synergistic action of the grease lubrication and the solid lubricant 49. On the other hand, the non-pressure-receiving surface 46 in operation performs only grease lubrication because the solid lubricant 49 is missing. Since the pressing force acting on the non-operating pressure receiving surface 46 is very small compared to the operating pressure receiving surface 41, only grease lubrication is sufficient.

In FIG. 2, the relative rotation amount between the bush 37 and the pin 38 (difference between mold clamping and mold opening) was about 45 °. Therefore, the pressure receiving surface 41 during operation is configured in a 120 ° fan shape.
On the other hand, in the drive link 27, the relative rotation amount between the bush 37 and the pin 38 (difference between mold clamping and mold opening) was about 80 °. Therefore, the pressure receiving surface 41 during operation is configured in a 180 ° fan shape.

  The pressure receiving surface at the time of operation of the bush was set in a range of 120 ° to 180 ° out of 360 ° per round. If the angle is set to 120 ° or more, the moving range of the toggle link can be sufficiently covered. Moreover, if it sets to 180 degrees or less, the waste of a solid lubricant can be avoided.

The present invention is characterized in that one bush 37 is divided into a pressure receiving surface during operation and a non-pressure receiving surface during operation. Since the solid lubricant 49 is not provided on the non-pressure-receiving surface 46 during operation, the required amount of the solid lubricant 49 is halved compared to the conventional case, and the procurement cost of the solid lubricant and the installation cost of the solid lubricant can be halved. it can.
Furthermore, if the amount of solid lubricant is halved, the amount of powder generated by wear is also halved. As a result, it is possible to greatly increase the time until the filler opening is closed, and to greatly extend the operating time of the toggle mechanism.

It is essential that the bush 37 is properly fitted to the boss 26R. A preferred method for fitting the bush 37 to the boss 26R will be described below.
FIG. 5 is an explanatory view of the bushing fitting method according to the present invention.
In (a), a punch mark 59 is engraved on the side surface 58 of the bush 37 and at the center position of the pressure receiving surface 41 during operation.
In (b), for example, a triangular mark 62 is engraved on the side surface 61 of the boss 26R. The mark 62 may be an arrow or a straight line.

The bush 37 is cooled in a low temperature room of about 50 ° C. below zero. Then, the outer diameter shrinks by the dimension obtained by multiplying the linear expansion coefficient by the temperature (room temperature 25 ° C.−under zero 50 ° C. = 75 ° C.).
When the bush 37 is taken out from the low temperature chamber, moisture in the air is frozen, frost is generated on the surface of the bush 37, and the punch mark 59 becomes difficult to see. Therefore, the punch mark 59 is exposed by wiping the frost with a dry cloth. In this state, the bush 37 is fitted into the hole 63 of the boss 26R.
Since the bush 37 returns to room temperature over time, it tries to return to the original outer diameter. That is, the outer peripheral surface of the bush 37 is pushed strongly so as to widen the hole 63 of the boss 26R, and a tight fitting state is completed. Thus, the bush 37 is fixed to the boss 26R.

  As shown in (c), when the pin 38 is inserted into the bush 37, the solid lubricant 49 indicated by the broken line becomes invisible. However, since the punch mark 59 is aligned with the mark 62, it can be easily confirmed visually that the solid lubricant 49 is placed at the correct position.

FIG. 6 shows another embodiment of FIG.
In (a), a small groove 65 having a key groove shape is formed on the outer periphery of the bush 37.
At (b), a large groove 66 is cut into the side surface 61 of the boss 26R. Then, an arrowed piece 67 having a size matching the large groove 66 is prepared. Next, this arrow-attached piece 67 is fitted into the large groove 66 and fixed with screws 68 and 68.
Then, the sufficiently cooled bush 37 is inserted into the hole 63 of the boss 26R from the back of the drawing.

  As shown in (c), when the pin 38 is inserted into the bush 37, the solid lubricant 49 indicated by the broken line becomes invisible. However, since the arrow mark 69 is contained in the small groove 65, it can be easily confirmed visually that the solid lubricant 49 is placed at the correct position.

  When the small groove 65 is cut over the entire length of the bush 37, the bush 37 can be inserted into the hole 63 from the front of the drawing.

In addition, the bush of this invention provided with the solid lubricant only on the pressure receiving surface at the time of operation can be applied not only to all the connecting portions of the toggle mechanism but also to some connecting portions of the toggle mechanism.
The solid lubricant may be provided with a recess on the inner peripheral surface of the bush and embedded in the recess.

  The present invention is suitable for a toggle type mold clamping device provided in a resin or metal injection molding machine.

It is a side view of the toggle type mold clamping device according to the present invention. FIG. 2 is an enlarged view of part 2 of FIG. 1. FIG. 3 is a three-part enlarged cross-sectional view of FIG. 2. It is explanatory drawing of the heat processing and plating process which concern on this invention. It is explanatory drawing of the fitting method of the bush which concerns on this invention. It is another Example figure of FIG. It is a figure explaining the basic composition of the conventional technology.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Toggle type clamping device, 11 ... Machine base, 12 ... Tie bar, 13 ... Fixed platen, 14 ... Pressure receiving plate, 15 ... Movable platen, 20 ... Toggle mechanism, 23, 38 ... Pin, 24, 37 ... Bush, 41 ··· pressure receiving surface during operation, 44 · tube joint as an element of grease supply means, 45 · grease tube as an element of grease supply means, 46 · non-pressure receiving surface during operation, 49 · solid lubricant, 54 · quenching layer, 57 ... plating layer.

Claims (3)

A fixed platen and pressure platen that are arranged opposite to each other on the machine base and connected by a tie bar, a movable platen that can be moved between the fixed platen and the pressure platen, and for extruding the movable plate to the fixed platen. This toggle mechanism includes a toggle mechanism that passes between the movable plate and the pressure platen. The toggle mechanism includes a bush, a pin that is inserted into the bush so as to be relatively rotatable, and a grease supply means that supplies grease to the lubrication surface of the pin. In a toggle type mold clamping device comprising:
The portion of the bush that receives a pressing action by the pin during mold clamping of this toggle type mold clamping device is referred to as a pressure receiving surface during operation, and the portion of the bush that is not subjected to the pressing action by the pin during mold clamping is a non-pressure receiving surface during operation. When calling
The toggle type mold clamping apparatus, wherein the bush does not include a solid lubricant on the non-pressure-receiving surface during operation, but includes a solid lubricant on the pressure-receiving surface during operation.   2. The toggle type mold clamping apparatus according to claim 1, wherein the pressure receiving surface during operation is set in a range of 120 ° to 180 ° out of 360 ° per rotation. The toggle type clamping apparatus according to claim 1, wherein the pin is provided with a quenching layer and a plating layer on a surface thereof by performing electroless composite plating after induction hardening.

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