Measuring and testing – Hardness – By penetrator or indentor
Reexamination Certificate
2002-09-13
2004-04-27
Raevis, Robert (Department: 2856)
Measuring and testing
Hardness
By penetrator or indentor
Reexamination Certificate
active
06725708
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an impression forming mechanism and an impression forming method which are employed in a testing apparatus that evaluates a material characteristics of a sample by applying a force to a surface of the sample with an indentor in order to from an impression thereon, and a hardness testing apparatus comprising the impression forming mechanism and method. The present invention also relates to a hardness testing apparatus and a hardness testing method, having an electromagnetic brake.
2. Description of the Related Art
In the related art, a hardness testing apparatus is known as a testing apparatus that evaluates the material characteristics of a sample based on an impression formed by applying a force (or load) to a surface of the sample with an indentor.
As a force applying mechanism in the hardness testing apparatus in the related art, for example, a mechanism shown in
FIG. 13
is known.
A hardness testing apparatus
100
as shown in
FIG. 13
is the so-called Rockwell type hardness testing machine. The hardness testing apparatus
100
has an impression forming mechanism
110
comprising weights
101
, a loading arm
102
, a cam
103
, a force shaft
104
, an indentor shaft
105
, an indentor
106
, etc, and a sample table
107
.
In the impression forming mechanism
110
, the weights
101
having a predetermined weight are hung from an end of the loading arm
102
. The end of the loading arm
102
moves down by the rotation of the cam
103
, and then a predetermined force (or load) is applied to the force shaft
104
. The force applied to the force shaft
104
is transmitted to the indentor
106
via the indentor shaft
105
. Thus, an impression is formed on a sample mounted on the sample table
107
, by a downward movement of the indentor
106
.
In a force applying control by using the weights, which is employed typically in the above hardness testing apparatus
100
, there is a problem that it cannot be confirmed whether the force having a set value is applied to the sample while an impression is formed on the surface of the sample.
Also, since the force is applied to the sample by using the weights, the force that exceeds a target force, i.e., the so-called overshoot, is generated unless a speed for applying the force to the sample is slowed down by a damper, or the like. There is also a problem that, even if the damper is employed, it is difficult to eliminate the small overshoot.
In order to overcome the problems, there is a method that the force is applied to the sample by executing electrically the force applying control. In the case of the electrical force applying control, the loading arm having a high rigidity is employed for the convenience of control.
Further, an electromagnetic brake is employed for stopping the sample table once when the sample is brought into contact with the indentor in order to apply a preliminary test force to the surface of the sample.
The electromagnetic brake uses an electromagnet that is arranged under the sample table, and if a predetermined force is applied to the indentor when the sample is brought into contact with the indentor, a current is passed through the electromagnet so that a brake is applied to an elevating operation of the sample table. With the electromagnetic brake, an operation of applying the force to the sample can be carried out precisely.
However, in the hardness testing apparatus having the loading arm with the high rigidity, an impact (stepwise force) is easily applied to the sample at an instant when the sample and the indentor are brought into contact with each other manually. In some cases, a force that excesses the preliminary test force is easily applied to the sample at an instant when the sample and the indentor are brought into contact with each other manually.
In such case, there is a problem that the hardness testing apparatus cannot be carried out preciously.
Further, for the sample table, a high mechanical strength and a high rigidity are required, and thus a magnetic substance such as iron, or the like is used as the material for the sample table. Accordingly, due to the use of the electromagnet of the electromagnetic brake, the sample table is magnetized and also the sample mounted on the sample table is magnetized.
Such magnetization is at the level that the measuring precision of the hardness testing apparatus is not influenced. However, in the test of the sample, such as a thin sample, a lightweight sample, or the like, which is easy to be attracted to the magnet, the sample is attracted to the electromagnet and pasted onto the sample table, whereby a replacing operation of the sample becomes troublesome.
SUMMARY OF THE INVENTION
The present invention has been made to overcome the above problems. In is a first object of the present invention is to provide an impression forming mechanism and an impression forming method and a hardness testing apparatus, having a loading arm with high rigidity, which can reduce an impact generated at an instant when an indentor and a sample are brought into contact with each other and also apply an preliminary test force to the sample easily and precisely.
Further, it is a second object of the present invention to provide a hardness testing apparatus and a hardness testing method, having an electromagnetic brake, which can test a thin sample, etc. effectively and also can test a sample, in which a problem is caused if the sample is magnetized.
In order to accomplish the first object above, the following means are adopted. According to a first aspect of the present invention, there is provided an impression forming mechanism for forming an impression on a surface of a sample with an indentor, comprising:
an impact reducing unit for controlling a movement of one of the sample and the indentor in a same direction as the other of the sample and the indentor when the sample comes close to the indentor and a distance between the sample and the indentor is within a predetermined distance.
According to the impression forming mechanism of the first aspect of the present invention, since the impact reducing unit is provided, the impulse that is applied to the sample by the indentor at an instant when the sample comes into contact with the indentor can be reduced. In other words, since the impact generated at an instant when the sample comes into contact with the indentor can be reduced, it is possible to overcome the problem such that the force exceeds a preliminary test force at an instant of contact.
In the impression forming mechanism of a second aspect of the present invention, according to the first aspect of the present invention, it is preferable that the impact reducing unit controls the movement of one of the sample and the indentor in a same direction as the other when the sample comes into contact with the indentor, the impact reducing unit including,
a force controlling unit for calculating a predetermined force which is to be applied to the sample, in response to a displacement from a reference position of the indentor when the sample comes into contact with the indentor, and
a moving unit for moving the indentor in a same direction as the sample such that the predetermined force calculated by the force controlling unit is applied to the sample.
According to the impression forming mechanism of the second aspect of the present invention, since the force controlling unit and the moving unit are provided, the force can be applied to the sample in response to the displacement from the reference position of the indentor. Thus, the operator who moves the sample manually can apply the predetermined force to the sample more appropriately by operating only the handle, etc. in the same manner as the related art.
In the impression forming mechanism of a third aspect of the present invention, according to the first or second aspect of the present invention, it is preferable that the impact reducing unit further includes a distance sensing unit for sensing the distance between the indentor and
Kawazoe Masaru
Oda Mituru
Yamada Tomoharu
Akashi Corporation
Raevis Robert
LandOfFree
Impression forming mechanism and method, and hardness... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Impression forming mechanism and method, and hardness..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Impression forming mechanism and method, and hardness... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3185683