BACKGROUND

FIELD OF THE INVENTION

The present invention generally relates to mould hardness and strength measuring devices. More particularly, the present invention relates to devices for measuring hardness and strength of moulds at deep pockets and cylindrical cavities.

DESCRIPTION OF THE RELATED ART

A hardness tester is a device for measuring the hardness of materials. Fig. 1 discloses a conventional mould hardness tester 100 to measure hardness of a mould. The mould hardness tester 100 has an indenter that is pushed against a surface of the mould and then either pushback resistance or diameter of the indentation or depth of indentation is measured. The indenter is usually made of a hard substance such as hardened steel, diamond, and the like. The softer the mould, the greater the penetration of the indenter. The tester has a digital or analog display for displaying the hardness of the mould. The indenter is co-axially aligned with tube of the tester 100.

A strength tester is a device for measuring the strength of materials. Fig. 1B discloses a conventional mould strength tester 200 to measure strength of a mould. The mould strength tester 200 has a tip that is pushed into surface of the mould and then resistance of mould to penetration of tip termed as mould strength of the mould is measured. The tester has a dial or digital indicator to read the strength of the mould. The tip is co-axially aligned with tube of the tester 200.

The existing hardness and strength testers are useful for detecting hardness and strength of mould having broad and shallow grooves. However, in order to detect hardness of mould when the mould surface has narrow and deeper grooves or holes or cylindrical cavities, the existing mould hardness testers cannot fit into those grooves to measure the hardness of side walls and base. Similarly, in order to detect strength of mould when the mould surface has narrow and deeper grooves or cylindrical cavities, the existing mould strength testers cannot measure the hardness of side walls of the grooves or cylindrical cavities. It is very important to measure both hardness and strength at these places, as these places usually are the critical points i.e., they have a much higher chance of experiencing greater stress than their strength and capability and are hence more prone to failure.

To summarize, if the depth of the grooves/holes are deep, the existing portable hardness and strength measuring devices cannot project probe (indenter or tip) into the bottom of the groove / bore to measure hardness and strength, respectively. Therefore, the existing portable hardness and strength measuring devices are not suitable to determine hardness and strength at meter deep trench / hole. Hence, there exists a need for devices which can measure hardness and strength of moulds at critical points, which are difficult to reach, such as deep pockets and narrow cylindrical cavities.

OBJECTS OF THE INVENTION

An object of the present invention is to measure hardness and strength of moulds at critical points such as narrow and deep pockets, recesses, and cylindrical cavities.

Another object of the present invention is to measure hardness and strength of side walls of the moulds.

Yet another object of the present invention is to develop portable hardness and strength measuring devices for the moulds.

SUMMARY OF THE INVENTION

The present invention discloses a device for determining hardness of a mould, the device comprises: a display unit and a measuring tube attached to the display unit. The device further includes an indenter that is positioned on a radial axis, which is substantially perpendicular to a longitudinal axis of the measuring tube. Moreover, the indenter extends from periphery of the measuring tube. The device further includes a sensor positioned in contact with the indenter. When the indenter is pressed against the mould, the sensor that is in contact with the indenter determines hardness of the mould, and the display unit displays the hardness of the mould. The device is mainly used to measure the hardness of moulds at critical points, which are difficult to reach, such as deep pockets and narrow cylindrical cavities. Moreover, the device is used to measure hardness and strength of side walls of the moulds.

BRIEF DESCRIPTION OF DRAWINGS

The features of the present invention, which are believed to be novel, are set forth with particularity in the appended claims. Embodiments of the present invention will herein after be described in conjunction with the appended drawings provided to illustrate and not to limit the scope of the claims, wherein like designations denote like elements, and in which:

Fig. 1 is an isometric view of a conventional mould hardness tester, in accordance with an embodiment of the present invention;

Fig. 2 is an isometric view of a conventional mould strength tester, in accordance with an embodiment of the present invention;

Fig. 3A is a front view of a hardness measurement device for moulds, in accordance with an embodiment of the present invention;

Fig. 3B is a side view of the hardness measurement device for moulds, in accordance with an embodiment of the present invention;

Fig. 3C is a side sectional view of the hardness measurement device for moulds, in accordance with an embodiment of the present invention;

Fig. 3D is a side sectional view of the hardness measurement device for moulds, in accordance with another embodiment of the present invention;

Fig. 3E is a front view of the hardness measurement device for moulds, in accordance with another embodiment of the present invention;

Fig. 3F is a front view of a mould with the hardness measuring device, in accordance with an embodiment of the present invention;

Fig. 4A is a side view of a hardness measuring system for moulds, in accordance with an embodiment of the present invention; Fig. 4B is an isometric view of top of a measuring probe of the hardness measuring system for moulds, in accordance with an embodiment of the present invention;

Fig. 4C is a side view of the measuring probe of the hardness measuring system for moulds, in accordance with an embodiment of the present invention;

Fig. 4D is an isometric view of bottom of the measuring probe of the hardness measuring system for moulds, in accordance with an embodiment of the present invention;

Fig. 4E is a front view of a mould with the hardness measuring system, in accordance with an embodiment of the present invention;

Fig. 5A is a front view of a strength measuring device for moulds with an analog display, in accordance with an embodiment of the present invention;

Fig. 5B is a side view of the strength measuring device for moulds, in accordance with an embodiment of the present invention;

Fig. 5C is a front view of the strength measuring device for moulds with a digital display, in accordance with another embodiment of the present invention;

Fig. 6A is a side view of a strength measuring system for moulds, in accordance with an embodiment of the present invention; and

Fig. 6B is a side view of a mould using the strength measuring system, in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

As used in the specification and claims, the singular forms“a”,“an” and“the” include plural references unless the context clearly dictates otherwise. For example, the term“an article” may include a plurality of articles unless the context clearly dictates otherwise.

Those with ordinary skill in the art will appreciate that the elements in the figures are illustrated for simplicity and clarity and are not necessarily drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated, relative to other elements, in order to improve the understanding of the present invention.

There may be additional components described in the foregoing application that are not depicted on one of the described drawings. In the event such a component is described, but not depicted in a drawing, the absence of such a drawing should not be considered as an omission of such design from the specification.

Before describing the present invention in detail, it should be observed that the present invention constitutes hardness and strength measuring devices for moulds. Accordingly, the components have been represented, showing only specific details that are pertinent for an understanding of the present invention so as not to obscure the disclosure with details that will be readily apparent to those with ordinary skill in the art having the benefit of the description herein.

As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which can be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. Further, the terms and phrases used herein are not intended to be limiting but rather to provide an understandable description of the invention.

A hardness measuring device 300 in accordance to an embodiment of the present invention is shown in Figs. 3A-3E. The hardness measuring device 300 includes a display unit 302 and a measuring unit 304. The measuring unit 304 includes a measuring tube 306 and an indenter 308. The measuring tube 306 is attached vertically to a bottom portion of the display unit 302. The measuring tube 306 is equipped at an end remote from the display unit 302 with the indenter 308. Further, the indenter 308 is positioned on a radial axis perpendicular to a longitudinal axis of the measuring tube 306. Moreover, the indenter 308 extends from an external periphery of the measuring tube 306 near its bottom end. In an embodiment, a tip of the indenter 308 may be a carbide ball. The tip of the indenter 308 may be, but not limited to, conical, cylindrical or diamond shaped. The indenter 308 is disposed perpendicular to a central longitudinal axis of the measuring tube 306.

The display unit 302 is provided with a digital display screen 310. Moreover, the display unit 302 houses a hardness sensor 312 and a microcontroller 314. The microcontroller 314 is equipped with an Analog-to-Digital converter (referred to as“A/D converter”). The A/D converter (not shown) assists the display unit 302 in displaying hardness values of a mould on the digital display screen 310. The A/D converter converts signals received from the hardness sensor 312 to digital signals, which can be further displayed on the digital display screen 310. In an embodiment, the microcontroller 314 may be equipped with a software that can be used to convert the signals received by the hardness sensor 312 to any specified hardness units. In another embodiment, the hardness sensor 312 may be positioned within the measuring tube 306.

As shown in Fig. 3C, the measuring tube 306 houses a vertically movable member 316 and a fulcrum 318. The vertically movable member 316 is coaxially aligned with the longitudinal axis of the measuring tube 306 and has a first end 320a and a second end 320b. The first end 320a of the vertically movable member 316 is in contact with the hardness sensor 312. The second end 320b of the vertically movable member 316 is in contact with the fulcrum 318. The vertically movable member 316 can be a spring or a combination of a connecting rod and a spring. The vertically movable member 316 extends into the display unit 302 to be in contact with the hardness sensor 312. The fulcrum 318 is pivoted to the measuring tube 306. In the measuring tube 306, one side of the fulcrum 318 is in contact with the indenter 308 and other side of the fulcrum 318 is in contact with the vertically movable member 306. The fulcrum 318 acts an impact transfer means that transfers the impact on the indenter 308 to the vertically movable member 316. As shown in Fig. 3C, the fulcrum 318 is of L-shape or curved shape. The indenter 308 may be in contact with the fulcrum 318 through a spring.

When the indenter 308 is pressed against the mould, the impact force is transferred to the fulcrum 318. As the fulcrum 318 is pivoted, the fulcrum 318 transfers the impact force to the vertically movable member 316. The movement of the vertically movable member 316 imparts pressure on the hardness sensor 312, leading to determination of hardness of the mould at that specific point. Once the vertically movable member 316 is pressed against the hardness sensor 312 upwardly, the vertically movable member 316 retracts from the hardness sensor 312, pushing the fulcrum 318 to its initial position. The fulcrum 318 further pushes the indenter 308 to its initial position. This allows the indenter 308 to bounce off from a surface of the mould. The rebound of the indenter 308 to its initial position is due to the vertically movable member 316. The vertically movable member 316 has a spring that pushes the vertically movable member 316 to its original position. In an embodiment, the hardness sensor 312 measures the speed of the tip of the indenter 308 before the impact and rebound speed after the impact. The ratio of the speeds is multiplied by 1000 is called the Leeb hardness number. The hardness sensor 312 records the impact and a corresponding signal is generated. In an embodiment, the hardness sensor 312 may be an accelerometer. The hardness sensor 312 generates signals which are further converted by the microcontroller 314 to display hardness value on the digital display screen 310.

Fig. 3D discloses another embodiment of the hardness measuring device 300. The hardness sensor 312 is positioned near the bottom end of the measuring tube 306, in accordance to another embodiment of the invention. The indenter 308 is positioned perpendicular to the longitudinal axis of the measuring tube 306 and is in contact with the hardness sensor 312 through a spring. The impact on the indenter 308 is transferred to the hardness sensor 312 through the spring. Further, the hardness sensor 312 is connected to the display unit 302 through a wired connection 322. When the hardness measuring device 300 is used to measure hardness of the mould, the tip of the indenter 308 hits the surface of the mould and after bounces off it. The hardness sensor 312 measures the speed of the tip of the indenter 308 before the impact and rebound speed after the impact. As shown in Fig. 3E, the hardness measuring device 300 may include a dial 324 that reads measured hardness values. In one embodiment, the hardness measuring device 300 is made of at least one of aluminium, polyester, plastic, or any other metal.

The position of the indenter 308 with respect to the measuring tube 306 allows the device 300 to measure the hardness of side walls of deeper and narrow pockets or recesses of a mould 3000 as shown in Fig. 3F. When the hardness measuring device 300 is lowered into deeper and narrow pockets of the mould 3000, the indenter 308 whose axis is perpendicular to the longitudinal axis of the measuring tube 306 then comes in contact with the mould 3000 at critical points. The hardness measuring device 300 is a portable device. Figs. 4A-4E disclose a hardness measuring system 400, in accordance to another embodiment of the invention. The device 400 includes a measuring probe 402 (hereinafter referred to as “probe 402”) and a remote display unit 404, as shown in Fig. 4A. Further, the probe 402 is connected to the remote display unit 404 through a wired connection 406. The remote display unit 404 includes a digital display screen 408 provided on its upper portion and a keypad (not shown) provided at its lower portion. The remote display unit 404 has a USB interface (not shown) that can be used for quickly and easily exchanging data with a PC. Moreover, the remote display unit 404 can be integrated with a software that can convert hardness value of a mould 4000 into Brinell, Rockwell, Vickers, and Shore hardness values. Further, the remote display unit 404 may have a printer (not shown) to print out final hardness values. As shown in Figs. 4B-4D, the probe 402 is a cylindrical- shaped device adapted to be hand-held and used by an operator to press against surface of a mould. The probe 402 is designed to be held by the operator. The probe 402 includes an indenter 410 at its bottom end. The indenter 410 is rounded so that it can impact the surface of the mould without damaging the mould. The probe 402 further includes a sensor (not shown) that is in contact with the indenter 410. The indenter 410 may be in direct contact with sensor or indirect contact with the sensor via a spring (not shown). In an embodiment, the sensor is an accelerometer. The sensor is connected to the remote display unit 404 via the wired connection 406. In one embodiment, the probe 402 is made of at least one of aluminium, polyester, plastic, or any other metal. As shown in Fig. 4E, the measuring unit 402 can be handheld so that the operator can use the probe 402 in any recess or pocket or cavity to measure hardness of the mould 4000.

A strength measuring device 500 according to the present invention is shown in Figs. 5A-5C. The indenter 308, which is of round shaped, of the hardness measuring device 300 is replaced with a cylinder-like structure to form the strength measuring device 500 that measures strength of a mould. The strength measuring device 500 is structurally and functionally similar to that of the hardness measuring device 300. The device 500 includes a display unit 502 and a measuring tube 504. In Figs. 5A-5B, the display unit 502 includes a digital display screen 506. The measuring tube 504 includes a pin 508 that protrudes perpendicularly out of a peripheral surface of the measuring tube 504 near its bottom end. The pin 508 is positioned perpendicular to a central axis of the measuring tube 504. The measuring tube 504 allows the device 500 to measure the resistance to penetration by top surface of deeper and narrow recesses or cylindrical cavities of a mould. The position of the pin 508 allows the device 500 to measure the strength of side walls of the deeper and narrow pockets or cylindrical cavities. When the measuring tube 504 is lowered into a deeper and narrow pocket, the pin 508 whose axis is perpendicular to the axis of the measuring tube 504 then comes in contact with the sidewall of the deeper and narrow pocket or cylindrical cavity. The pin 508 is pressed into the surface of the mould and the digital display screen shows the number that indicates resistance to penetration of the pin 508 by the mould, termed as the mould strength of the sidewall of the mould. The device 500 helps in measuring strength of moulds at critical points. The strength measuring device 500 is a portable device. In Fig. 5C, the device 500 includes a dial 510 to read values of mould strength.

Figs. 6A-6B disclose a strength measuring system 600, in accordance to an embodiment of the invention. The indenter 410, which is of round shaped, of the hardness measuring system 400 is replaced with a cylinder-like structure to form the strength measuring system 600 that measures strength of a mould. The strength measuring system 600 is structurally and functionally similar to that of the hardness measuring system 400. The device 600 includes a cylindrical probe 602 and a remote display unit 604 as shown in Fig. 6A. The cylindrical probe 602 has a pin 606 that protrudes from its bottom end. The cylindrical probe 602 further includes a sensor (not shown) that is in contact with the pin 606. The pin 606 may be in direct contact with sensor or indirect contact with the sensor via a spring (not shown). In an embodiment, the sensor is an accelerometer. The sensor is connected to the remote display unit 604 via a wired connection 608. The remote display unit 604 includes a display screen 610 provided on its upper portion. As shown in Fig. 6B, the cylindrical probe 602 can be handheld so that a user can use the cylindrical probe 602 in any recess or pocket or cavity to measure strength of a mould 6000.

The devices 300, 400, 500, and 600 of the present invention have reasonable design, simple structure, and stability. The devices 300, 400, 500, and 600 are convenient to operate and easy to carry. Moreover, the devices 300 and 400 are mainly used to measure the hardness of moulds at critical points, which are difficult to reach, such as deep pockets and narrow cylindrical cavities. The devices 500 and 600 are mainly used to measure the strength of moulds at critical points, which are difficult to reach, such as deep pockets and narrow cylindrical cavities. The devices 300 and 400 are very convenient to use for measuring hardness of side walls of the moulds. The devices 500 and 600 are very convenient to use for measuring strength of side walls of the moulds. The present invention has been described herein with reference to a particular embodiment for a particular application. Although selected embodiments have been illustrated and described in detail, it may be understood that various substitutions and alterations are possible. Those having ordinary skill in the art and access to the present teachings may recognize additional various substitutions and alterations are also possible without departing from the spirit and scope of the present invention.