JPH0748362Y2 - Detection head protection structure - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a protective structure for a detection head of a digitizer, a copying milling machine, a coordinate measuring machine or the like.

[Conventional technology]

In order to process a workpiece having a complicated contour shape by a copying milling machine or the like, the stylus of the detection head is moved along the contour of the model, but the stylus may collide with the model due to an erroneous operation by an operator. In such a case, an excessive load is applied to the detection shaft, which causes plastic deformation or damage to the internal structure of the detection head.

In such cases, the machine may be stopped and the detection head repaired or replaced, but if deformation occurs inside, it cannot be seen from the outside, so copying processing can be continued without replacing the detection head. There is a possibility that processing defects will occur. Therefore, when the stylus is excessively displaced, an electric signal is issued to brake the feed shaft, or the rigidity of the detection shaft is reduced, and when an excessive load is applied, the shaft is elastically deformed. Protect the internal structure of the detection head,
It has been proposed that the detection head be detached from its mounting mechanism when a load higher than the setting is applied.

[Problems to be solved by the device]

However, in such a conventional protection structure, the entire detection head becomes large due to the extra stroke, and the measurement accuracy decreases due to an increase in the amount of deflection of the detection shaft due to contact pressure. There was a drawback that it became complicated.

The present invention solves the above-mentioned problems of the prior art, and provides a protective structure for a detection head that does not reduce the rigidity of the detection shaft, has a lightweight and simple structure, and can be easily replaced. To aim.

[Means for Solving the Problems]

The purpose of this is to protect the detection head when a lateral force is applied to a stylus mounted on the tip of the detection shaft of the detection head built into the housing. -Shaped circular hole provided in the housing and having a predetermined inner diameter, a breaking member made of a hard brittle material interposed between the detection shaft and the stylus, and the breaking member detachably attached to the detection shaft. Protecting a detection head including mounting means for mounting and a thin portion formed on the breaking member so that a predetermined portion of the breaking member contacts when the detection shaft or the breaking member contacts the circular hole and is further bent. Achieved by structure.

[Action]

During normal operation, the stylus moves along the contour of the model and is displaced within the range of the circular hole, and based on this, the detection head detects the coordinates of the measurement point in the X, Y, Z directions.

However, if the stylus is excessively displaced in the X and Y directions due to an erroneous operation other than copying, the detection axis collides with the inner wall of the circular hole of the mechanical stopper and prevents further displacement. . If an unreasonable displacement exceeding this is applied, the breaking member made of the hard brittle material such as ceramics, which has excellent rigidity but is relatively brittle, breaks, and more force is applied to other parts inside the housing including the detection head body. It does not reach.

The broken parts are immediately replaced with spare parts by the attaching means, and the work is restarted in a short time.

Hereinafter, the present invention will be described in more detail with reference to the preferred embodiments shown in the drawings.

〔Example〕

FIG. 1 shows a housing 1 of a detection head of the present invention, a detection shaft 2 held in a suspended state by a detection head (not shown) built therein, and a housing 1 attached to the tip of the detection shaft 2 downward. It is a partially expanded side view of the protruding stylus 3.

A circular hole 4 having a predetermined diameter is provided in the lower portion of the housing 1, and the inner peripheral wall thereof constitutes a mechanical stopper.
That is, the normal displacement of the stylus 3 in the XY plane is limited to the range of the circular hole 4.

The detection shaft 2 of the present invention comprises a shaft body 2a and a replacement part 2b attached to the lower end thereof, and a stylus 3 is fixed to the lower end of the replacement part 2b. Incidentally, as shown in FIG. 2, the conventional detection shaft 2 does not have such a replacement part 2b, and the stylus 3 is directly attached to the shaft body 2a.

As shown in FIG. 3, the replacement part 2b has a tube-shaped breaking member 10 made of ceramics or the like (hereinafter, referred to as a hard brittle material) that has high rigidity but is brittle against bending, and also has a tubular shape. The holder 11 is made of steel, and the upper portion of the holder 11 is fitted to the outer periphery of the breaking member 10 and integrally fixed by an adhesive to form a replaceable component. As is clear from the figure, this replacement part 2b has a hollow portion that penetrates the inside thereof in the axial direction.

In order to assemble each of these parts, first, the small diameter portion 12 at the upper portion of the breaking member 10 is fitted into the internal space at the lower portion of the shaft body 2a, and the bolt 13 is passed through an axial hole passing through the small diameter portion 12.
Is tightened into the screw hole 14 on the shaft body 2a side. As a result, the replacement part 2b is fixed to the lower end of the shaft body 2a. Next, the small-diameter portion 15 on the upper portion of the stylus 3 is fitted into the inner space of the lower portion of the holder 11 and fixed by the set screw 16 through the side wall.

The operation of the detection head protection structure of the present invention thus constructed will be described below.

In a normal working state, the stylus 3 moves along the contour of the model and is displaced within the range of the circular hole 4, based on which the detection head detects the coordinates of the measurement point in the X, Y, Z directions. .

However, when a large load and displacement are applied to the tip of the stylus 3 due to an erroneous operation other than the normal copying operation,
A part of the replacement part 2b collides with the inner wall of the circular hole 4 to prevent further displacement. However, beyond this, X, Y
When a displacement in the direction is applied to the tip of the stylus 3, the breaking member 10 of the replacement part 2b is bent around the portion in contact with the inner wall of the circular hole 4, and the breaking member 10 moves in the thinnest region in terms of material dynamics. It breaks as shown in Fig. 4.

Due to the breakage of the breaking member 10, it is possible to prevent an unreasonable force from being transmitted to the detection head through the shaft body 2a.

The remains of the breaking member 10 remaining on the shaft body 2a side are removed by loosening the bolts 13, and a new replacement part 2b prepared in advance is newly attached. Then, the stylus 3 is detached from the broken member 10 and is newly attached as a replacement part.
It is fixed to the tip of 2b by a set screw 16.

In this example, as the breaking member 10, a tube-shaped hard and brittle material having a thin portion is used, but as shown in FIG. 5, a structure in which a deep groove 20 is partially provided all around may be used.

[Effect of device]

As described above, according to the present invention, when an excessive displacement is applied to the stylus during work, the breaking member made of a hard and brittle material that is incorporated in advance is broken, and an excessive force is detected including the head body. Since it does not reach the upper region of the head, the work is continued without knowing that the shaft has been deformed, and the disadvantage that the machining accuracy is deteriorated is eliminated.

Further, the broken replacement part can be removed and installed by loosening the mounting means, for example, one bolt, so that the replacement work can be performed quickly on site and the operating efficiency of the machine is improved.

Since the malfunction of the worker is shown in the form of breakage of parts, management becomes easy.

[Brief description of drawings]

1 is a partially enlarged side view of a detection head shaft according to a first embodiment of the present invention, FIG. 2 is a partially enlarged side view of a conventional detection head shaft, and FIG. 3 is a side view of the present invention. 4 is an exploded side view of the replacement part of the first embodiment, FIG. 4 is a partially enlarged side view of the detection head shaft showing the broken state of the breaking member, and FIG. 5 is a side view of the breaking member of the second embodiment of the present invention. It is a figure. 1 …… Detection head housing 2 …… Detection shaft 2a …… Shaft body 2b …… Replacement part 3 …… Stylus 4 …… Circular hole 10 …… Break member 11 …… Holder 13 …… Bolt 14 …… Screw hole

Claims (1)

[Scope of utility model registration request] 1. A protective structure for a detection head when a lateral force is applied to a stylus mounted on the tip of the detection shaft of a detection head built into a housing, wherein the detection shaft is provided on the outer periphery of the detection shaft. A circular hole provided in the housing concentrically with a predetermined inner diameter, a breaking member made of a hard brittle material interposed between the detection shaft and the stylus, and the breaking member attached to and detached from the detection shaft. A detection head comprising a mounting means that is freely attached and a thin portion formed on the breaking member so that a predetermined portion of the breaking member breaks when the detection shaft or the breaking member abuts against the circular hole and is further bent. Protection structure.