GB2093759A

GB2093759A - Means for measuring the mould locking force of an injection moulding machine

Info

Publication number: GB2093759A
Application number: GB8137391A
Authority: GB
Original assignee: ENGEL KG L; LUDWIG ENGEL KG
Current assignee: ENGEL KG L; LUDWIG ENGEL KG
Priority date: 1980-12-22
Filing date: 1981-12-11
Publication date: 1982-09-08
Also published as: SE8107615L; IT8125726A0; GB2093759B; DE8034172U1; FR2496548A1; IT1169288B

Abstract

In an injection moulding machine a device for measuring the mould locking force is placed in a shaft (1) which is stretched by said force. The device comprises a pin (13) resting against the bottom of an axial pocket hole (12) in said shaft, the relative displacement between the respective free ends of the shaft (1) and the pin (13) yielding a measure of the locking force. The displacement moves a ferro-magnetic body (16) attached to the end of pin (13) relative to a sensor (14) initiating a signal which is relayed to a motor for driving a locking force adjustment mechanism. <IMAGE>

Description

SPECIFICATION Means for measuring the mould locking force of an injection moulding machine This invention relates to means for measuring the mould locking force of an injection moulding machine, comprising a mould carrier plate abutting on traverses under the influence of a displacement mechanism, preferably including a toggle lever, the stretch of at least one of said traverses yielding a measure for the mould locking force.

A toggle lever injection moulding machine comprising means for measuring and adjusting the mould locking force has, for example, been described in the AT-PS 356 831. The mould locking force is determined in that two arms spaced from each other are fastened to a traverse of the injection moulding machine, and that the distance between the arms is measured by means of an inductive contactless sensor. It has proved disadvantageous that the structural elements required for measuring the mould locking force lie within a region of maintenance and operation.

Even slight contact may cause faulty measuring as the stretch of the traverse or change of its length, which is due to the mould locking force, lies within a range of some hundredths of a millimeter.

It is, therefore, the object of the present invention to improve means of the abovedescribed kind allowing high-precision measuring of the mould locking force, on the one hand, and definitely eliminating the possibility of unintentional damage, on the other hand.

According to the invention this is achieved by adapting one end of a measuring pin to rest against the bottom of an axial pocket hole in one traverse, a sensor indicating the displacement of the other end of the measuring pin relative to the end of the traverse.

Hence, the structural elements required for determining the stretch of the traverse or measuring the mould locking force are arranged in a protected position and impede in no way the operation or maintenance of the machine.

It is preferably provided that a bearing block with a recess being concentric in respect of the pocket hole is fastened to the end of the traverse, the sensor being adjustable in said recess in axial direction.

It is further of advantage if the end of the measuring pin extending into a recess is of reduced diameter and if one or a number of springs pressing the measuring pin against the bottom of the pocket hole are arranged between the reduced diameter portion of the measuring pin and the bearing block.

In the following an embodiment of the invention will be described in more detail by means of the figures of the drawing.

Figure 1 shows a schematic view of a toggle lever injection moulding machine whose mould locking force is automatically maintained at a constant value, and Figure 2 shows a schematic view of the means for measuring the mould locking force by means of the stretch of the traverse.

The toggle lever injecting moulding machine illustrated in Fig. 1 comprises a rigid mould carrier plate 2' and a mould carrier plate 2 movably mounted alongside traverses 1. Said mould carrier plate 2 is by means of a toggle lever mechanism linked to a hinge plate 7 adjustable fastened to said traverses 1. Mould halves 3 and 3' are mounted on the two mould carrier plates 2 and 2', respectively. The mould tocking force of this toggle lever injection moulding machine is determined by measuring the stretch of the traverses. To this end, a measuring means 9 is associated with one of said traverses 1, the output signal of said means being fed to a processing device 8. Said processing device 8 actuates a motor 6 changing the position of the hinge plate 7 in the desired direction.

The measuring means for determining the stretch of the traverse or the mould locking force has been illustrated in detail in Fig. 2. An axial pocket hole 12 is provided in the traverse 1, a measuring pin 13 resting against the bottom of said pocket hole. The other end of the measuring pin 13 is of reduced diameter and extends into a recess 11 of a multipart bearing block 10 arranged at the end of the traverse. A spring assembly 1 5 comprising a number of saucer springs and pressing the measuring pin 13 against the bottom of the pocket hole 12 is arranged between the bearing block 10 and the reduced diameter portion of the measuring pin 13. A sensor 14 is axially adjustably screwed into the recess 11. Said sensor indicates the displacement of the external end of the traverse 1.To this end, a ferromagnetic body 16 is screwed to the reduced diameter portion of the measuring pin 13, said body extending into a coil arranged in the sensor 14. If the mould 3 is locked because of a stretch of the toggle joints 4, the traverse 1 stretches. Said stretch is proportional to the mould locking force.

The position of the external end of the measuring pin 13 is accordingly changed by the stretch length D, whereby the position of the ferromagnetic body 1 6 within the coil of the sensor 14 is changed. This effects an inductance variation, which is processed in a known manner.

It is obvious that a sensor of different construction may be used instead of the sensor described herein. It is an essential advantage of the measuring means according to this invention that its essential structural elements are arranged in a protected position and do not impede the operation of the injection moulding machine.

1. Means for measuring the mould locking force of an injection moulding machine, comprising a mould carrier plate abutting on traverses under the influence of a displacement mechanism, preferably including a toggle lever, the stretch of at least one of said traverses yielding a measure for the mould locking force, wherein one end of a measuring pin rests against the bottom of an axial

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Means for measuring the mould locking force of an injection moulding machine This invention relates to means for measuring the mould locking force of an injection moulding machine, comprising a mould carrier plate abutting on traverses under the influence of a displacement mechanism, preferably including a toggle lever, the stretch of at least one of said traverses yielding a measure for the mould locking force. A toggle lever injection moulding machine comprising means for measuring and adjusting the mould locking force has, for example, been described in the AT-PS 356 831. The mould locking force is determined in that two arms spaced from each other are fastened to a traverse of the injection moulding machine, and that the distance between the arms is measured by means of an inductive contactless sensor. It has proved disadvantageous that the structural elements required for measuring the mould locking force lie within a region of maintenance and operation. Even slight contact may cause faulty measuring as the stretch of the traverse or change of its length, which is due to the mould locking force, lies within a range of some hundredths of a millimeter. It is, therefore, the object of the present invention to improve means of the abovedescribed kind allowing high-precision measuring of the mould locking force, on the one hand, and definitely eliminating the possibility of unintentional damage, on the other hand. According to the invention this is achieved by adapting one end of a measuring pin to rest against the bottom of an axial pocket hole in one traverse, a sensor indicating the displacement of the other end of the measuring pin relative to the end of the traverse. Hence, the structural elements required for determining the stretch of the traverse or measuring the mould locking force are arranged in a protected position and impede in no way the operation or maintenance of the machine. It is preferably provided that a bearing block with a recess being concentric in respect of the pocket hole is fastened to the end of the traverse, the sensor being adjustable in said recess in axial direction. It is further of advantage if the end of the measuring pin extending into a recess is of reduced diameter and if one or a number of springs pressing the measuring pin against the bottom of the pocket hole are arranged between the reduced diameter portion of the measuring pin and the bearing block. In the following an embodiment of the invention will be described in more detail by means of the figures of the drawing. Figure 1 shows a schematic view of a toggle lever injection moulding machine whose mould locking force is automatically maintained at a constant value, and Figure 2 shows a schematic view of the means for measuring the mould locking force by means of the stretch of the traverse. The toggle lever injecting moulding machine illustrated in Fig. 1 comprises a rigid mould carrier plate 2' and a mould carrier plate 2 movably mounted alongside traverses 1. Said mould carrier plate 2 is by means of a toggle lever mechanism linked to a hinge plate 7 adjustable fastened to said traverses 1. Mould halves 3 and 3' are mounted on the two mould carrier plates 2 and 2', respectively. The mould tocking force of this toggle lever injection moulding machine is determined by measuring the stretch of the traverses. To this end, a measuring means 9 is associated with one of said traverses 1, the output signal of said means being fed to a processing device 8. Said processing device 8 actuates a motor 6 changing the position of the hinge plate 7 in the desired direction. The measuring means for determining the stretch of the traverse or the mould locking force has been illustrated in detail in Fig. 2. An axial pocket hole 12 is provided in the traverse 1, a measuring pin 13 resting against the bottom of said pocket hole. The other end of the measuring pin 13 is of reduced diameter and extends into a recess 11 of a multipart bearing block 10 arranged at the end of the traverse. A spring assembly 1 5 comprising a number of saucer springs and pressing the measuring pin 13 against the bottom of the pocket hole 12 is arranged between the bearing block 10 and the reduced diameter portion of the measuring pin 13. A sensor 14 is axially adjustably screwed into the recess 11. Said sensor indicates the displacement of the external end of the traverse 1.To this end, a ferromagnetic body 16 is screwed to the reduced diameter portion of the measuring pin 13, said body extending into a coil arranged in the sensor 14. If the mould 3 is locked because of a stretch of the toggle joints 4, the traverse 1 stretches. Said stretch is proportional to the mould locking force. The position of the external end of the measuring pin 13 is accordingly changed by the stretch length D, whereby the position of the ferromagnetic body 1 6 within the coil of the sensor 14 is changed. This effects an inductance variation, which is processed in a known manner. It is obvious that a sensor of different construction may be used instead of the sensor described herein. It is an essential advantage of the measuring means according to this invention that its essential structural elements are arranged in a protected position and do not impede the operation of the injection moulding machine. CLAIMS

1. Means for measuring the mould locking force of an injection moulding machine, comprising a mould carrier plate abutting on traverses under the influence of a displacement mechanism, preferably including a toggle lever, the stretch of at least one of said traverses yielding a measure for the mould locking force, wherein one end of a measuring pin rests against the bottom of an axial pocket hole in one of said traverses, and wherein a sensor indicates the displacement of the other end of said measuring pin relative to the end of said traverse.

2. Means according to claim 1, wherein a bearing block having a concentric recess in respect of said pocket hole is fixed to the end of said traverse, said sensor being adjustable in said recess in axial direction.

3. Means according to claim 2, wherein the end of said measuring pin extending into said recess has a reduced diameter, and wherein one spring or a number of springs pressing said measuring pin against the bottom of said pocket hole are arranged between said reduced diameter portion of said measuring pin and said bearing block.

4. Means according to one of claims 1 through 3, wherein a ferromagnetic body is linked to the end of said measuring pin, said body extending into a coil arranged in said sensor.

5. Means substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.