JP2767678B2 - Spring type hardness measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring the hardness of a sample by pressing an indenter into the sample, and more particularly to a spring-type hardness measuring apparatus suitable for automatic measurement of Vickers hardness and Brinell hardness. .

[0002]

2. Description of the Related Art Conventionally, in order to measure Vickers hardness and Brinell hardness, the size of an indentation on a sample is measured with a microscope or the like, and then each hardness is determined based on the size. .

[0003]

In the conventional measuring means,
As described above, there is a problem that the hardness cannot be quickly measured because the measurement such as the reading of the dimensions is performed by a person.

[0004] It is an object of the present invention to solve such a problem and to provide a spring-type hardness measuring apparatus capable of automatically performing hardness measurement. Still another object of the present invention is to provide a spring-type hardness measurement device capable of replacing a test load unit with an initial load unit. Another object of the present invention is to provide a spring-type hardness measurement device that allows easy selection of a test load. Still another object of the present invention is to provide a spring-type hardness measuring apparatus which can measure hardness under a large test load while having a compact configuration.

[0005]

In order to achieve the above object, a spring-type hardness measuring apparatus according to claim 1 of the present invention comprises:
In a spring-type hardness measuring device provided with a measuring unit including an initial load unit B and a test load unit A disposed above the initial load unit B, the initial load unit B is used as an outer frame member. Mounting cylinder 5 and pressing cylinder 5
Seat 10 having a conical receiving surface 10a provided on the
An intermediate cylinder 7 that is vertically movably disposed inside the pressing cylinder 5 and has an abutting surface with the conical receiving surface 10a; and a connection cylinder 12 at a lower end of the intermediate cylinder 7. And a pressing spring having an upper end supported by the pressing cylinder 5 to apply a pressing load to the reference piece 27. 24, an indenter shaft 8 that is vertically movably disposed inside the intermediate cylinder 7 and has an abutting surface with a conical receiving surface 27a formed on the reference piece 27, and a lower end of the indenter shaft 8 An indenter 13 attached to the portion, an initial load spring 25 whose upper end is supported by the intermediate cylinder 7 to apply an initial load to the indenter 13, and an upper end surface connected to the upper end of the indenter shaft 8. an intermediate shaft 21 provided with a load receiving 20, the
The test load unit A includes a displacement meter for measuring a relative displacement between the intermediate cylinder 7 and the indenter shaft 8.
A test load case 3 as an outer frame member, a receiving seat 18 provided with a conical receiving surface 18a provided on the test load case 3, and a lower end portion movably up and down inside the test load case 3. A load shaft 16 disposed so as to face the load receiver 20, and a test load spring 2 whose upper end is supported by the test load case 3 to apply a test load to the load shaft 16. constructed, the reference piece with respect to the above reference pieces when pressed against the surface of the sample, the difference between the displacement of H ₂ in the displacement H ₁ and test load state in the initial load state of the indenter (H ₀ = H ₂ −H ₁ ) is provided, and a display for converting the hardness into the hardness of the sample and displaying the converted hardness is provided.

The spring-type hardness measuring apparatus according to the second aspect is the spring-type hardness measuring apparatus according to the first aspect,
Said indicator, said reference piece of the indenter at the time when you return to an initial load state displacement H ₁ and the test load state is removing the test load relative to the said reference piece of the indenter in an initial load state the difference between the displacement _{H 3} which is the reference _{(H 00} =
H ₃ −H ₁ ) is converted into the hardness of the sample and displayed.

According to a third aspect of the present invention, there is provided a spring-type hardness measuring apparatus according to the first or second aspect, wherein the pressing cylinder 5 as an outer frame member of the initial load unit B is provided. The test load case 3 as an outer frame member of the test load unit A is formed in a cylindrical body having substantially the same diameter, and the test load unit A can be connected to the initial load unit B so as to be convertible. It is characterized by being constituted.

According to a fourth aspect of the present invention, there is provided a spring-type hardness measuring apparatus according to any one of the first to third aspects, wherein the test load of the test load unit A can be selected. It is characterized by being constituted.

According to a fifth aspect of the present invention, there is provided a spring-type hardness measuring apparatus according to any one of the first to third aspects, wherein the test load spring is mounted on the load shaft with respect to the load shaft. It is characterized by being constituted by a plurality of coil springs of the same kind for small loads arranged on concentric circles.

Further, in the spring-type hardness measuring device according to the present invention, in the spring-type hardness measuring device according to the first or second aspect, the displacement meter is formed on the intermediate shaft 21. A long hole 21a in the longitudinal direction, a supporting member 6 protruding from the intermediate cylinder 7 so as to penetrate the long hole 21a, a differential coil 22 supported by the supporting member 6, and a differential coil 22 Protruding from the indenter shaft 8 so as to be positioned inside the
And a core shaft 23 forming a differential transformer.

According to a seventh aspect of the present invention, there is provided a spring-type hardness measuring apparatus according to the first or second aspect, wherein the displacement meter is constituted by a linear scale. Features.

[0012]

In the spring-type hardness measuring apparatus according to the first aspect of the present invention, two types of loads, an initial load and a test load, are applied to the indenter. On the other hand, the load of the pressing spring is applied to the reference piece. Then, the state (position) where the reference piece is in contact with the sample
The displacement meter detects the difference between the displacement of the indenter in the initial load state (penetration depth into the sample) and the displacement in the test load state (penetration depth into the sample), and based on the detected value, A hardness measurement is made.

[0013] In the spring-type hardness measuring apparatus according to the second aspect, the displacement of the indenter in the initial load state with respect to the reference piece and the return of the indenter from the test load state to the initial load state after the test load is removed from the test load state. Is detected, and the hardness of the sample is measured based on the detected value. Claim 3
In the spring-type hardness measurement device described in the above, in the measurement unit composed of the initial load unit and the test load unit,
Since the test load unit is exchangeably connected to the initial load unit, the test load unit, that is, the test load can be selected.

Further, in the spring-type hardness measuring apparatus according to the fourth aspect, a test load can be selected, and in the spring-type hardness measuring apparatus according to the fifth aspect, a large test can be performed with a compact configuration. Hardness test by load becomes possible.
In the spring-type hardness measuring device according to the sixth aspect, the relative displacement between the reference piece and the indenter is measured by the differential transformer, and in the spring-type hardness measuring device according to the seventh aspect, the reference piece is connected to the reference piece by the linear scale. The relative displacement with the indenter is measured.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 (a) and FIG. 1 (b) are schematic diagrams for explaining the principle of measurement, and FIG. 3 is a side sectional view of the measuring unit, FIGS. 4 and 5 are side sectional views of the measuring unit at the time of hardness measurement, FIG. 6 is a side view thereof, FIG. 7 is a front view thereof, and FIG. FIG. 9 is a side sectional view of a modification of the measuring unit.

First, the principle of hardness measurement according to the present invention will be described. First, the first measurement method will be described.
In (a), reference numeral 13 denotes an indenter, and a reference piece 27 is provided so as to surround the indenter 13. At the time of measurement, the indenter 13 is pressed against the surface S of the sample 14 by the initial load f ₁ (this state is referred to as “initial load state”), and the reference piece
27 is pressed against the surface S by pressing load f _c.
The displacement of the indenter 13 with respect to the reference piece 27 at this time
Measuring the H ₁ (penetration depth into the sample).

Next, a test load f ₂ is applied to the indenter 13.
This state is called a “test load state”, and a load “f ₁ + f ₂ ” is added to the indenter 13. Then, the displacement (depth of penetration into the sample) of the indenter 13 with reference to the reference piece 27 at that time H
₂ is measured, and the difference H ₀ = H ₂ −H ₁ of the displacement (depth of penetration) based on the reference piece 27 of the indenter 13 is calculated. On the other hand, the relationship between the difference H ₀ of the indentation depth of the indenter and the hardness K was previously determined by an experiment.
Alternatively, a graph or a mathematical expression as shown in FIG. Then, the hardness of the sample is measured by converting the H ₀ calculated in the above procedure into the hardness of the sample using the graph or mathematical formula of FIG.

Next, a second measuring method will be described. Fig. 1 (b)
In the measurement time, first sample 1 indenter 13 by the initial tension f ₁
4 with pressed against the surface S of the reference piece 27 is pressed against the surface S by pressing load f _c. Measuring a displacement H ₁ reference piece 27 indenter 13 relative to the at that time, then adding the test load f ₂ to the indenter 13 and the test load state, then removing the test load f ₂ return to an initial load state , displacement (depth of penetration into the sample) of the indenter 13 relative to the reference piece 27 at the time of H ₃ measures, calculates a H ₀₀ = H ₃ -H _1. Then, by the same procedure as in the case of the above-described first measurement method,
That using equation or graph is prepared in advance by an experiment or definition type, performing hardness measurement of a sample by converting the H ₀₀ in hardness.

Next, a specific structure of the measuring device will be described. As shown in FIG. 3, the measuring unit 60 includes a test load unit A and an initial load unit B, and is entirely formed in a cylindrical shape. Reference numeral 5 denotes a pressing cylinder as an outer frame member of the initial load unit B. A test load case 3 as an outer frame member of the test load unit A is replaceable by screw connection on the upper part of the pressing cylinder 5. Is to be connected to. Note that the pressing cylinder 5 and the test load case 3 are formed to have the same outer diameter, and both are integrated by screw connection.

The pressing cylinder 5 is provided with a receiving seat 10 having a conical receiving surface 10a which is electrically insulated via an insulating piece 11 and has an intermediate cylinder 7 inside and below the pressing cylinder 5. While being movably disposed, the conical contact surface formed at the lower end abuts on the conical receiving surface 10a of the seat 10, so that downward movement is restricted. I have. Symbol 9 is a seat 10
FIG.

The intermediate cylinder 7 is disposed so as to be able to move up and down inside the pressing cylinder 5 by being guided by the sliding piece 4 mounted on the upper part thereof.
A reference piece 27 having a cylindrical shape is attached to the sample table C. The reference piece 27 is disposed so as to face the surface of the sample 14 placed on the sample table C. The lower end surface of the reference piece 27 is in contact with the surface of the sample 14. The upper end portion of the intermediate cylinder 7 is supported by the pressing cylinder 5, and “f”
₁ + the lower end of the f _c "is pressing force can impart a pressing spring 24 is engaged. An indenter shaft 8 is provided along the vertical center axis of the intermediate cylinder 7.

Below the indenter shaft 8, a conical receiving portion of the reference piece 27 is provided.
A spring receiver 26 that can be brought into contact with 27a is attached, and an indenter 13 is attached to the lower end of the indenter shaft 8. The upper end of the indenter shaft 8 is supported by the intermediate cylinder 7, and the lower end of an initial load spring 25 capable of applying an initial load of f ₁ to the indenter 13 is engaged with the indenter shaft 8.
The lower end of an intermediate shaft 21 disposed along the vertical center axis of the intermediate cylinder 7 is screw-connected to the upper end of the indenter shaft 8. The intermediate shaft 21 is movably fitted to the opening of the center portion of the slide piece 4, so that the indenter shaft 8 can move vertically in the intermediate cylinder 7 integrally with the intermediate shaft 21. .
Reference numeral 20 indicates a load receiver mounted on the top surface of the intermediate shaft 21.

An elongated hole 21a is formed in the intermediate portion of the intermediate shaft 21 in the axial direction. In the elongated hole 21a, a support fitting 6 protruding from the intermediate cylinder 7 is provided. A coil 22 constituting a differential transformer is mounted on the support fitting 6. On the other hand, a core shaft 23 is protruded from the indenter shaft 8, and the upper end of the core shaft 23 is extended into the coil 22 to measure the relative displacement between the reference piece 27 and the indenter 13 together with the coil 22. It constitutes a differential transformer as a displacement meter. Note that a linear scale or the like may be used as the displacement meter instead of the differential transformer. The initial load unit B is configured as described above.

On the other hand, the test load case 3 is provided with a load shaft 16 such that the lower end thereof faces the load receiver 20 on the upper end surface of the intermediate shaft 21. It is slidably guided in the vertical direction by the spring receiver 1 screwed to the load case 3, and further supports the lower portion of the lower part of the test load case 3 through the spring receiver 17 attached to the load shaft 16 via the insulating piece 19. And is supported by a receiving seat 18 having a conical receiving portion 18a. Further, a load shaft is provided between the spring support 17 and the spring support 1.
A test load spring 2 that can apply a test load to the indenter shaft 8 via 16 is interposed. The test load unit A is configured as described above.

Since the seat 10 and the seat 18 are both electrically insulated, the initial load detection switches S ₁ , S ₁ , S ₂ , S ₃ , S ₄ , S ₄ , S ₅ , S ₈ , S 17, S 18, S 17, S 18, S 17, S 18, S 17, S 18 are used. It is constituted the test load detecting switch S _2, thereby, the load state detection mechanism in the switch S ₁ and S ₂ can detect initial load load condition and test load application state, respectively, are configured. Note that the switches S ₁ and S ₂ are turned on.
The off state is displayed on a pilot lamp 56 (see FIGS. 6 and 7) of the display 55. The measurement unit 60 having the above-described configuration is mounted on a test table 59 shown in FIG. 6 when measuring hardness.

The test table 59 has a shape similar to a tabletop drilling machine. By rotating the pressing handle 58 in the direction of arrow X, the measuring unit 60 is moved in the Y direction and the indenter 13 and the reference piece 27 are moved to the sample 14. Can be pressed against. The indenter shaft 8 comes into contact with the conical receiving surface 27a when no load is applied, so that the indenter 13 protrudes slightly from the lower end of the reference piece 27 (indicated by the dimension a). At this time, a gap b is maintained between the load receiver 20 and the lower end surface of the load shaft 16 that is larger than the protrusion amount a of the indenter.

When the measuring unit 60 is pressed down, the indenter 13 first comes into contact with the sample 14 and the reference piece 27 is moved from the spring receiver 26 of the indenter shaft 8.
Is released downward, and the initial load f ₁ by the initial load spring 25 is applied to the indenter 13. When the measurement unit 60 is further depressed, the reference piece 27 comes into contact with the sample 14, further measuring unit 60 is depressed, the switch S ₁ is turned OFF the lower end of the middle tube 7 is separated from the seat 10 . Then, the pressing force of the reference piece 27 f _c is also a state where the initial load f ₁ applied (referred to as a reference load condition) to the indenter 13.

At this point, an interval is maintained between the load receiver 20 and the lower end surface of the load shaft 16. Electromotive force corresponding to the protrusion amount H ₁ of the indenter 13 with respect to the reference piece 27 at the time of the reference load state (state of FIG. 4) is generated in the coil 22 of the differential transformer, its value is incorporated in the display unit 55 Stored in the computer. When the measuring unit 60 is further pushed down,
Abuts the lower end load receiving 20 loading axis 16, a test load f ₂ by the test load spring 2 spring receiver 17 of the load axis 16 is separated from the conical receiving surface 18a of the seat 18 is added to the indenter 13 You. The switch S ₂ is turned off by the detachment of the spring support 17 from the receiving surface 18a.
It became FF and the pilot lamp
Appears on 56.

[0029] Then, this state is measured by the amount of protrusion H ₂ initial load state and similar means from the reference piece 27 of the indenter 13 in (test load state, the state of FIG. 5), and H ₂ and above of an H ₁ The difference H ₀ = H ₂ −H ₁ is calculated by a computer in the display 55, and this (H ₀ ) is converted into hardness based on a previously input calculation formula. Displayed as hardness. The reference numeral 61 in FIG.
Reference numeral 62 denotes a screw shaft for vertically moving the sample receiving table 61, reference numeral 63 denotes a nut for fixing the screw shaft 61, and reference numeral 64 denotes a machine frame.

FIG. 7 shows a portal-type test table 70 suitable for a large test load such as 3000 kgf. In this case, the measuring unit 60 is attached to the upper and lower frames 66, and rotates the screw shafts 68 and 75, which are screw-engaged with the upper and lower frames 66, in the direction of arrow U to move the upper and lower frames 66 in the direction of arrow V. A hardness test is performed by pressing an indenter or the like of the measurement unit 60 against the sample 14 on 65. Reference numeral 72 in FIG. 7 indicates an operation box also serving as a display, and reference numeral 74 indicates an operation switch. Drives for screw shafts 68 and 75 (motors, reduction gears, etc.)
Reference numeral 71 is built in a machine frame 69 of a test stand 70.

Next, a modified example of the test load unit A will be described. In FIG. 8, first to third three test load springs 40, 41, 42 are disposed inside the test load case 3. That is, the first spring 42 is interposed between the spring bearing 33 attached to the load shaft 16 and the spring bearing 39 attached to the inner surface of the test load case 3. The second spring 41 and the third spring 40 are loosely fitted on the load shaft 16 in a floating manner and are sequentially stacked on the spring support 33.
32, 31 and spring supports 38, 37 attached to the inner surface of the test load case 23, respectively.

Further, a catching cylinder 34 is loosely fitted on the load shaft 16, and a load selection knob 30 is attached to the upper end of the catching cylinder 34. Male thread 30a at the center of the load selection knob 30
The female screw 36a screwed with the male screw 30a is formed in the center of the lid 36 of the test load case 3.
Further, the catching cylinder 34 is formed with stepped portions 34a and 34b which are sequentially engaged with the spring receivers 31 and 32. Reference numeral 35 in FIG. 8 indicates an index for reading the rotation amount of the load selection knob 30, and reference numeral 28 indicates a stopper for limiting the movement amount of the load selection knob 30. The guide portion 37 of the catch cylinder 34 is provided in the center hole of the spring receiver 37.
a is formed.

In the above configuration, when both the step portions 34a and 34b are detached from the spring supports 31 and 32 (the state shown in FIG. 8), the three springs 40 to 42 are connected to the test load via the spring supports 33. Acts as a spring. When the load selection knob 30 is rotated from this state to pull up the lifting cylinder 34, first, the step portion 34a
The spring 31 is pulled up by engaging with the spring 31, and the third spring 40 does not function as a test load spring. Further load selection knob
When the catch cylinder 34 is pulled up by rotating the 30, the step portion 34 b pulls up the spring receiver 32, so that the second spring 41 also does not act as a test load spring. Thus, the test load can be selected by rotating the load selection knob 30.

In the modification shown in FIG. 9, the test load spring in the test load unit A is replaced by a plurality of coil springs of the same kind for small loads (only two of the springs 44 and 51 are shown in FIG. 9). ) To generate a large test load with a small spring. Reference numerals 43 and 50 in FIG. 9 denote spring supports mounted on the test load case 3 so as to be adjustable in height, and reference numeral 3a denotes a guide hole for the vertical movement of the load shaft 16. In the case of this modification, the plurality of springs are evenly arranged concentrically with respect to the load shaft 16, and the abutment portion of the seat 18 against the conical receiving surface is located at the center of the spring receiver 17. Is formed. Further FIG.
Has a configuration in which the initial load unit B can be adapted to a large test load.

That is, a plurality of small-load coil springs of the same kind (only two of the springs 46 and 54 are shown in FIG. 9) are provided inside the pressing cylinder 5 in the middle cylinder. 7 is arranged so as to be evenly arranged on a concentric circle. Further, the indenter is constituted by a ball indenter 47, and is attached to the indenter shaft 8 via a cap 48 and an indenter holder 49 so that it can cope with a large test load.

[0036]

As described above, according to the spring-type hardness measuring apparatus of the present invention, the following effects and advantages can be obtained. (1) The hardness of a sample can be measured by a simple operation of pressing the measurement unit against the surface of the sample. (2) The test load can be changed, and thus a wide range of hardness measurement from a small test load of about several gf to a large test load of 3000 kgf is possible. (3) It is possible to provide a hardness measuring device with a large test load in a compact configuration.

[Brief description of the drawings]

FIG. 1 (a) is a schematic diagram for explaining the measurement principle of the present invention. (b) A schematic diagram for explaining the measurement principle of the present invention.

FIG. 2 is the same graph.

FIG. 3 is a side sectional view of a measuring unit of the spring-type hardness measuring device as one embodiment of the present invention.

FIG. 4 is a side sectional view of the measuring unit at the time of measuring hardness.

FIG. 5 is a side sectional view of the measuring unit at the time of hardness measurement.

FIG. 6 is a front view of the spring-type hardness measuring device.

FIG. 7 is a front view of the spring-type hardness measuring device for the large test load.

FIG. 8 is a side sectional view of a modified example of the test load unit.

FIG. 9 is a side sectional view of a modification of the measurement unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Spring support 2 Test load spring 3 Test load case 4 Sliding piece 5 Pressing cylinder 6 Support bracket 7 Intermediate cylinder 8 Indenter shaft 9 Support ring 10 Receiving seat 10a Conical surface receiving surface 11 Insulating piece 12 Connecting cylinder 13 Indenter 14 Sample 15 Lid 16 Load shaft 17 Spring bearing 18 Seat 18a Conical bearing surface 19 Insulating piece 20 Load bearing 21 Intermediate shaft 22 Coil 23 Core shaft 24 Pressing 25 Initial load spring 26 Spring catch 27 Reference piece 27a Conical face Receiving surface 30 Load selection knob 31-33 Spring catch 34 Fishing catch 37-39 Spring catch 40 Third spring 41 Second spring 42 First spring 44, 46, 51, 54 Coil spring 55 Display 56 Pilot lamp 57 Measurement value display Panel 58 Push handle 59, 70 Test bench 60 Measurement unit

Claims (7)

(57) [Claims] 1. A spring-type hardness measuring apparatus comprising a measuring unit 60 comprising an initial load unit B and a test load unit A disposed above the initial load unit B, wherein the initial load unit B is Pressing cylinder 5 as outer frame member
A receiving seat 10 having a conical receiving surface 10a provided on the pressing cylinder 5; and a receiving seat 10 disposed vertically movably inside the pressing cylinder 5 and for receiving the conical receiving surface 10a. An intermediate cylinder 7 having an abutting surface; and a cylindrical reference piece 27 attached to a lower end of the intermediate cylinder 7 via a connecting cylinder 12 so as to be able to abut from above the sample on the sample stage C.
A pressing spring 24 whose upper end is supported by the pressing cylinder 5 so as to apply a pressing load to the reference piece 27; The indenter shaft 8 having an abutting surface against the conical receiving surface 27a formed on the indenter 13, the indenter 13 attached to the lower end of the indenter shaft 8, and the upper end in order to apply an initial load to the indenter 13 Intermediate cylinder 7
, A first load spring 25 supported by the indenter shaft 8, an intermediate shaft 21 connected to the upper end of the indenter shaft 8 and having a load receiver 20 on the upper end surface, and a relative displacement between the intermediate cylinder 7 and the indenter shaft 8. The test load unit A includes a test load case 3 as an outer frame member, and a receiving seat 18 provided on the test load case 3 and having a conical receiving surface 18a. A load shaft 1 disposed inside the test load case 3 so as to be able to move up and down and to have a lower end portion facing the load receiver 20;
6 and a test load spring 2 whose upper end is supported by the test load case 3 so as to apply a test load to the load shaft 16. When the reference piece is pressed against the surface of the sample, of with respect to the above reference pieces, the difference between the displacement of H ₂ in a test load state and the displacement H ₁ in the initial load state of the indenter (H 0 ₌ H ₂ -
A spring-type hardness measurement device, comprising: a display for converting H ₁ ) into the hardness of the sample and displaying the converted hardness. 2. A spring-type hardness measuring apparatus according to claim 1, said indicator, said test load displacement H ₁ and test load condition relative to the said reference piece of the indenter in an initial load state Is removed and the difference (H ₀₀ = H ₃ −H ₁ ) from the displacement H ₃ of the indenter with respect to the reference piece when returning to the initial load state is converted into the hardness of the sample and displayed. A spring-type hardness measuring device characterized by having the following configuration. 3. The spring-type hardness measuring apparatus according to claim 1, wherein the pressing cylinder 5 as an outer frame member of the initial load unit B and the test load as an outer frame member of the test load unit A. The case 3 is formed of a cylindrical body having substantially the same diameter, and is configured such that the test load unit A can be exchangeably connected to the initial load unit B. Measuring device. 4. The spring-type hardness measuring apparatus according to claim 1, wherein a test load of the test load unit A is selectable.
Spring type hardness measuring device. 5. The spring-type hardness measuring apparatus according to claim 1, wherein said test load spring is a plurality of coils of the same kind for a small load arranged on a concentric circle with respect to said load axis. A spring-type hardness measuring device comprising a spring. 6. The spring-type hardness measuring device according to claim 1, wherein the displacement meter penetrates an elongated hole 21a formed in the intermediate shaft 21 in an axial direction and an elongated hole 21a. The supporting bracket 6 protruding from the intermediate cylinder 7, the differential coil 22 supported by the supporting bracket 6, and the indenter shaft 8 protruding from the differential coil 22. A spring type hardness measuring device, comprising: a core shaft 23 forming a differential transformer together with the differential coil 22; 7. The spring-type hardness measuring device according to claim 1, wherein the displacement meter is configured by a linear scale.