Hardness tester

A hardness tester includes a supporting frame having a guiding channel, a driving axle slidably disposed in the supporting frame, and a penetrating pin, having a pin head, coaxially disposed in the guiding channel in a slidably movable manner to coaxially align with the driving axle for the pin head to penetrate on a testing surface of a tested object. A linear displacement device includes a transmission shaft movably disposed in the supporting frame at a position universally contacting between the driving axle and the penetrating pin, and a displacement sensor supported at the transmission shaft, wherein when the driving axle is driven for applying a penetrating force to the penetrating pin through the transmission shaft, the linear sensor detects a linear displacement of the transmission shaft with respect to the penetrating pin for measuring the hardness of the tested object.

BACKGROUND OF THE PRESENT INVENTION

1. Field of Invention

The present invention relates to a material hardness measuring device, and more particularly to a hardness tester, which allows the user to precisely measure the hardness of the material having a limited testing surface thereof.

2. Description of Related Arts

Hand-operated portable hardness meters are already known wherein a conventional hardness meter generally comprises a supporting frame having a flat supporting platform and an actuating gun comprising a driving pin slidably to align with the supporting platform in such a manner that when the testing material is positioned between the supporting platform and the driving pin, a penetrating force of the driving pin is exerted on the testing material so as to determine the hardness of the testing material through the penetrating force. Accordingly, the penetrating force includes a major loading force and a minor loading force wherein the result of the hardness test is determined by the depth of the indention on the testing material with respect to the minor loading force. However, such conventional hardness meter has several drawbacks.

In order to align the testing material between the supporting platform and the driving pin to test the hardness of the testing material, the testing material must provide a flat testing surface for the driving pin to penetrate thereon and a flat supporting surface to bias against the supporting platform. Accordingly, the testing surface and the supporting surface of the testing material must be flat and parallel with each other. Therefore, the testing material having an irregular shaped cannot be tested by such convention hardness meter. Otherwise, the test result of the hardness of the testing material will not accurate due to the uneven testing surface or the uneven supporting surface of the testing material.

Moreover, in order to measure the hardness of the testing material, the actuating gun generally comprises a force sensor angularly detect a linear displacement of the driving pin for determining the penetrating force of the driving pin, such that the force sensor is arranged to read the penetrating force of the driving pin by converting the linear displacement of the driving pin into an angular movement. In other words, the linear displacement of the driving pin is detected and converted to an angular displacement through a L-shaped measuring arm of the force sensor. Therefore, the test result may not precise due to the mechanical deviation of the force sensor.

Alternatively, the measurement device is arranged to read the penetrating force of the driving pin through a compression spring to convert the linear displacement of the driving pin by means of the spring compression force. Accordingly, the penetrating force of the driving pin is converted to the spring compression force by determining the spring coefficient. However, it is known that the compression spring will be deteriorated after a period of time. In other words, both conventional measurement devices of the hardness meter cannot precisely determine the hardness of the testing material due to the mechanical deviation.

SUMMARY OF THE PRESENT INVENTION

A main object of the present invention is to provide a hardness tester, which allows the user to precisely measure the hardness of the material having a limited testing surface thereof.

Another object of the present invention is to provide a hardness tester, which comprises a driving axle coaxially aligned with a penetrating pin, and a transmission shaft physically contacted between the driving axle and the penetrating pin for transmitting the penetrating force from the driving axle to the penetrating pin so as to minimize the error of the test result through the testing operation due to the unwanted lateral movement of the driving axle.

Another object of the present invention is to provide a hardness tester, wherein no supporting surface of the testing material is required during the testing operation of the hardness tester of the present invention so as to minimize the error of the test result through the testing operation due to the irregular shape of the testing material.

Another object of the present invention is to provide a hardness tester, which comprises a displacement sensor for detecting a linear displacement of the penetrating pin by means of electric capacity, so as to precisely measure the hardness of the material.

Another object of the present invention is to provide a hardness tester, wherein the displacement sensor is supported by the transmission shaft to detect the linear displacement of the penetrating pin so as to enhance the accuracy of the test result.

Another object of the present invention is to provide a hardness tester, wherein the force sensor is operated independently with the penetrating pin so as to prevent the force sensor from being damage by the reaction of the penetrating force of the penetrating pin.

Another object of the present invention is to provide a hardness tester, which can incorporate with a supporting arm having a supporting platform to bias against the supporting surface of the testing material for enhancing the testing operation, wherein the supporting platform is adapted to be selectively adjusted to fit on the supporting surface of the testing material so that the testing material having an uneven supporting surface with respect to the testing surface can be tested by the hardness tester of the present invention.

Another object of the present invention is to provide a hardness tester constructed as a hand-operated portable hardness meter which is advantage in practice use.

Accordingly, in order to accomplish the above objects, the present invention provides a hardness tester for measuring a hardness of a tested object having a testing surface, comprising:

a supporting frame having a receiving chamber and an elongated guiding channel coaxially extended to communicate with the receiving chamber;

a driving axle slidably disposed in the receiving chamber of the supporting frame;

a penetrating pin, having a pin head, coaxially disposed in the guiding channel in a slidably movable manner to coaxially align with the driving axle for the pin head to penetrate on the testing surface of the tested object; and

a linear displacement device, comprising a transmission shaft movably disposed in the receiving chamber at a position universally contacting between the driving axle and the penetrating pin, and a displacement sensor supported at the transmission shaft, wherein when the driving axle is driven for applying a penetrating force to the penetrating pin through the transmission shaft, the linear sensor detects a linear displacement of the transmission shaft with respect to the penetrating pin for measuring the hardness of the tested object.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring toFIGS. 1 and 2of the drawings, a hardness tester according to a preferred embodiment of the present invention is illustrated, wherein the hardness tester is adapted for measuring a hardness of a tested object1having a testing surface.

The hardness tester comprises a supporting frame10having a receiving chamber11and an elongated guiding channel12coaxially extended to communicate with the receiving chamber11, a driving axle20slidably disposed in the receiving chamber11of the supporting frame10, and a penetrating pin30coaxially disposed in the guiding channel12in a slidably movable manner to coaxially align with the driving axle20for the pin head31to penetrate on the testing surface of the tested object1.

The hardness tester further comprises a linear displacement device40which comprises a transmission shaft41movably disposed in the receiving chamber11at a position universally contacting between the driving axle20and the penetrating pin30, and a displacement sensor42supported by the transmission shaft41, wherein when the driving axle20is driven for applying a penetrating force to the penetrating pin30through the transmission shaft41, the linear sensor42detects a linear displacement of the transmission shaft41with respect to the penetrating pin30for measuring the hardness of the tested object1.

According to the preferred embodiment, the supporting frame10, which is made of rigid material such as metal, comprises a hand-held casing13defining the receiving chamber11therein, a driving wheel14rotatably mounted to the hand-held casing13for applying the penetrating force on the driving axle20via a gear unit141, and a tubular guiding cylinder15which is extended from the hand-held casing13and defines the guiding channel12, wherein an opening edge151of the guiding cylinder15is arranged for biasing against the testing surface of the tested object1to guide the pin head31of the penetrating pin30to penetrated thereon.

As shown inFIG. 2, the opening edge151of the guiding cylinder15has a flat surface for substantially biasing against the testing surface of the tested object1in such a manner that the opening edge151of the guiding cylinder15functions as a guiding surface to guide the pin head31of the penetrating pin30for perpendicularly penetrating on the testing surface of the tested object1.

Therefore, the tested object1requires a relatively small testing surface in a flat manner that enough the opening edge151of the guiding cylinder15to bias thereon in such a manner that the penetrating pin30is guided to coaxially slide along the guiding channel12of the guiding cylinder15to precisely penetrate the pin head31at the testing surface of the tested object1.

The supporting frame10further comprises a resilient element17disposed within the guiding channel12for applying an urging force against the penetrating pin30to retain the penetrating pin30in a normal testing position. The resilient element17, according to the preferred embodiment, is a compression spring coaxially mounted to the penetrating pin30wherein the resilient element17has two ends biasing against the penetrating pin30and an inner wall of the guiding channel12respectively to slidably push the penetrating pin30within the guiding channel12.

Accordingly, while releasing the penetrating force after the penetrating pin30is pushed to slidably extend the pin head31thereof out of the guiding channel12at the opening edge151for penetrating on the testing surface of the tested object1, the compressed resilient element17is rebounded to slidably push the penetrating pin30back into the guiding channel12.

As shown inFIG. 2, the transmission shaft41has a driven end411universally contacting with the driving axle20and a driving end412universally contacting with the penetrating pin30wherein the transmission shaft41is adapted for transmitting the penetrating force from the driving shaft20to the penetrating pin30. Accordingly, when the penetrating force is applied on the driving axle20to drive the driving axle to slidably move forward, the penetrating pin30is pushed to slide the pin head31thereof out of the opening edge151of the guiding channel12through the transmission shaft41. It is worth to mention that when the driving wheel14applies the penetrating force on the driving axle20, an unwanted lateral movement of the driving axle20may be created. As a result, the actual linear displacement of the penetrating pin30cannot be detected. However, when the penetrating force is transmitted to the penetrating pin30through the transmission shaft41, the transmission shaft41is adapted to minimize the unwanted lateral movement of the driving axle20to the penetrating pin30, so as to enhance the detection of the linear displacement of the penetrating pin30with respect to the test object1.

Accordingly, when the penetrating force is applied on the driving axle20, the transmission shaft41transmits the penetrating force as a downward pushing force to slidably push the pin head31of the penetrating pin30out of the opening edge151of the guiding channel12, such that even if the driving axle20is not precisely align with the penetrating pin30in a coaxial manner, the transmission shaft41is adapted to adjust the penetrating force to push the penetrating pin30to coaxially slide along the guiding channel12for penetrating on the testing surface of the tested object1so as to enhance the accuracy of the test result.

The displacement sensor42comprises a linear sensor circuit421supported within the receiving chamber11and first and second linear sensor terminals422,423electrically coupling with the sensor circuit421and the transmission shaft41respectively in such a manner that when the transmission shaft41is driven to move within the receiving chamber11, the linear sensor circuit421detects the linear displacement of the transmission shaft41with respect to a positioning differentiation between the linear first and second terminals422,423.

It is worth to mention that the linear displacement of the transmission shaft41is corresponding to a linear displacement of the penetrating pin30that the pin head31is penetrated on the testing surface of the tested object1because the penetrating force is transmitted to the penetrating pin30through the transmission shaft41. Therefore, by detecting the linear displacement of the transmission shaft41, the hardness result of the tested object can be measured via the penetrating force.

In addition, since the transmission shaft41is universally contacted between the driving axle20and the penetrating pin30for transmitting the penetrating force thereto, the penetrating force does not directly exert to the displacement sensor42so as to prevent the displacement sensor42from being damage due to the penetrating force.

As shown inFIG. 4, the hardness tester further comprises a force sensor50supported within the receiving chamber11to couple with the driving axle20for detecting the penetrating force thereon. The force sensor50, such as a load cell, comprises a force sensor circuit51supported at the receiving chamber11and first and second force sensor terminals52,53electrically coupling with the force sensor circuit51and the driving axle20respectively, in such a manner that the force sensor circuit51is adapted for detecting the penetrating force on the driving axle20with respect to a positioning differentiation between the first and second force sensor terminals52,53. Therefore, when the penetrating force of the driving axle20and the linear displacement of the penetrating pin30are respectively detected by the force sensor50and the displacement sensor42, the hardness of the tested object1can be measured through the hardness measuring circuit as shown inFIG. 3.

As shown inFIG. 1, the supporting frame10further comprises a display screen16electrically connected between the force sensor50and the displacement sensor42for displaying the test result of the tested object1via the hardness measuring circuit through the penetrating force of the driving axle20and the linear displacement of the penetrating pin30.

The hardness tester further comprises a retaining frame60extended from the supporting frame10, wherein the retaining frame60has a supporting platform601adjustably aligned with the pin head31of the penetrating pin30for substantially retaining the opening edge151of the guiding channel12at the testing surface of the tested object1.

As shown inFIG. 1, the retaining frame60comprises a retaining arm61having a L-shaped extended from the supporting frame10and a supporting member62which defines the supporting platform601thereon and is mounted at a free end of the retaining arm61in a rotatably movable manner such that the opening edge151of the guiding channel12and the supporting platform601are adapted for substantially biasing against the tested object1to align the pin head31of the penetrating pin30with the testing surface of the tested object1.

Accordingly, the supporting member62has a spherical bottom portion rotatably mounted to the free end of the retaining arm61to rotatably adjust the supporting platform601for fittingly biasing against the tested object1. It is worth to mention that the retaining arm61is detachably attached to the supporting frame10to support the supporting member62so as to retain a distance between the opening edge151of the guiding channel12and the supporting platform601. Therefore, the user is able to select a corresponding size of the retaining arm61with respect to the thickness of the tested object1such that the tested object1can be substantially held between the opening edge151of the guiding channel12and the supporting platform601in position.

It is worth to mention that the testing surface and the supporting surface of the tested object1must be flat and parallel with each other for the conventional hardness measuring device. However, the supporting platform601can be selectively adjust to bias against the supporting surface of the tested object1such that the tested object1having an irregular shaped can be tested by the hardness tester of the present invention.