Nail gun for measuring material strength

Abstract

The invention relates to a portable and non-destructive nail gun for easy measurement of the compressive strength of materials such as rock, concrete and brick.

Description

[0001] DESCRIPTION

[0002] NAIL GUN FOR MEASURING MATERIAL STRENGTH

[0003] Technical Field

[0004] The invention relates to a portable and non-destructive nail gun for easy measurement of the compressive strength of materials such as rock, concrete and brick.

[0005] Prior Art

[0006] Compressive (or compressive) strength is one of the most important engineering parameters for most construction materials. One of the most important materials tested for compressive strength is rock, which is used directly as building stone in engineering structures or as aggregate for concrete. Compressive strength testing is one of the most widely applied tests for all types of rocks in geological engineering and mining engineering. Compressive strength testing is also a must for construction concrete. It is possible to expand the range of building materials subjected to compressive strength testing to include bricks, briquettes, dry building mortar and many other similar materials.

[0007] Although direct measurement of compressive strength in the laboratory may seem simple, it is a time-consuming and somewhat costly experiment, given the requirements (e.g. ASTM, 2002[4]) to obtain good quality core specimens with loading planes parallel to each other, and to test the experiment on several "identical" specimens of the same rock (or concrete).

[0008] Many devices and methods have been developed for the "indirect" determination of compressive strength both in the laboratory and in the field (in situ) in a shorter time, with less cost and easy-to-transport devices, or devices developed for other purposes have been used in the determination of compressive strength of building materials, especially rocks. The most prominent of these are Schmidt hardness test, needle penetration test and nail penetration test. Schmidt hardness test can be performed according to ISRM (1978)

[0010] and ASTM (2001)[3]standards. There are two types, L and N type, and the difference between them is only a small change in impact energy. N type hammer, which has higher impact energy, is more preferred in rocks. Type L is also used to approximately determine the compressive strength of concrete. The Schmidt hardness test is recommended for rocks with a compressive strength of 20-150 MPa (ISRM, 1978)

[0010] ; it does not give reliable results for rocks with compressive strength less than 10 MPa (Li et al., 2000)

[0013] . The main advantages of this test technique are that it is easy to implement, the cost of the setup is low and the cost of testing is zero, easy portability and repeatability. It is never a completely reliable test for rock / concrete strength, but it is a type of test that is usually performed to have an opinion about the compressive strength.

[0009] The point loading test (ASTM, 1995)[2]is recommended for rocks with compressive strength greater than 15 MPa (Broch and Franklin, 1972)[7]. It can be applied on cylindrical, prismatic and irregular shaped specimens. The setup cost is low and the test cost depends on the specimens used. The cost of testing irregularly shaped specimens is zero. The point load strength [Is(50>] obtained by this test is multiplied by a certain coefficient to obtain the compressive strength. Bieniawski ( 1975)[6]23, Broch and Franklin (1972)[7]24 and ISRM (1985)

[0011] ] suggested a coefficient between 20-25. This conversion coefficient is very speculative and according to Yilmaz and Sendir (2002)

[0029] it can vary between 6 and 105. Finding the compressive strength by multiplying the point load strength by a certain coefficient is an extremely crude approach. It can only give a rough idea about the compressive strength of the rock.

[0010] The Disk Shear Test (van der Schrier, 1988

[0026] ; Ulusay et al., 2001

[0025] ) is performed on specially prepared thin, disk-shaped specimens and is applied on rocks with a compressive strength range of 0.5-70 MPa. As in many other experiments, the effect of specimen size and anisotropy on the experimental results was reported to be great. It requires special specimen preparation. The Equotip hardness measurement setup was initially developed for metals and then applied to rocks by a limited number of researchers (e.g. Verwaal and Mulder, I993P7]; Aoki and Matsukura, 2008[1]). The range of applicability for compressive strength is 0.1-100 MPa. The degree of accuracy with which this test method gives the compressive strength is not yet clear.

[0011] Needle penetration test was developed to overcome the deficiencies encountered in point loading test, Schmidt hardness test, shear index test etc. in extremely weak to very weak rocks. It can go as low as 0.3 MPa for compressive strength. The upper limit of measurement is 40 MPa (Maruto Corporation, 2006

[0016] ; Ngan-Tillard et al., 2011[

[18] ). When the compressive strength increases to the range of 30-40 MPa, it shows deviations of up to 30% compared to the values obtained from the standard direct measurement experiment. It has been reported to have large uncertainties in predicting compressive strength and has been proposed as an index test rather than a test that accurately determines compressive strength. Bae et al. (2004)[5]used a pneumatic pin penetration test to test the compressive strength of shotcrete at different curing levels in tunnel walls. After conducting a series of experiments in the laboratory with the test setup, they showed that the empirical formulas developed can predict the compressive strength of shotcrete with a high degree of accuracy from the penetration depths obtained from the pin penetration test in field tests on shotcrete.

[0012] Liberatore et al. (2003)

[0014] developed a special penetrometer to indirectly determine the mortar strength in masonry structures. The penetrometer assembly was driven into the joint mortars of different historical buildings by repeated driving operations. The lengths of the penetration varied between 40-50 mm and it was stated that the number of drives required to penetrate 1 mm into the mortar varied between 0.54-1.23. Felicetti and Gattesco (1998)[9]developed a dynamic penetrometer to measure mortar strength in masonry structures. The impact energy of the penetrometer was reported to be 2.2 J. These researchers also looked for a relationship between the penetration depth of the penetrometer and the compressive strength of the mortar. The researchers stated that the scatter between these two parameters is very small in laboratory tests, while the scatter is high in historical buildings. The possible reason for this is that the porosity of mortars in real buildings is more variable, the mortar composition is less homogeneous and the physical properties of the binding material. It was stated that the strength range of the mortar they studied was 0.25-2.5 MPa.

[0013] One of the recent studies to indirectly determine the compressive strength of rocks is the nail penetration test (Kayabah and Selguk, 2010

[0012] ; Selguk et al., 2012

[0023] ; Selguk and Kayabah, 2015[

[122] ). With this alternative technique, compressive strength can be measured between 5-100 MPa. Kayabah and Selguk (2010)[

[0012] reported that the compressive strength determined indirectly by the nail penetration test gives one-to-one results with the compressive strength determined by the direct method; the ability of the nail penetration test to determine the compressive strength is superior to the Schmidt hardness hammer and point loading test. Selguk et al. (2012)

[0023] also applied the nail penetration test to concrete specimens and reported that the results obtained from nail penetration tests on concrete specimens with different aggregates were in good agreement (R2>0.95) with the results obtained from the test technique used to determine the compressive strength directly; and that the nail penetration test accurately gives the combined effect of aggregate and paste on strength. Selguk and Kayabah (2015)

[0022] applied the nail penetration test with nail guns of different energy and nail diameter to determine the compressive strength and developed an empirical relationship to predict the compressive strength as a function of nail penetration depth, nail gun energy and nail diameter. Palassi and Emami (2014)

[0019] developed a mechanical nailer with a mass of 4.54 kg and a drop height of 0.46 m and conducted a series of experiments on travertines and marbles, keeping the energy constant at 122 J for a total of 6 drives. Using 3.5 mm diameter nails, they identified an exponential relationship between the uniaxial compressive strength of intact rock and the depth of nail penetration with a regression coefficient of 0.98.

[0014] Yilmaz (2009)

[0028] introduced a new test method called "core choke test (CST)" for indirect determination of the free compressive strength (UCS) of rock core samples. The principle of this test depends on the type of "choke" of a core loaded along a circle perpendicular to its long axis. Mishra and Basu (2012)

[0017] investigated the applicability of the block punch test in estimating the UCS and Brazilian tensile strength of some granites, shales and sandstones in India. In this study, it was experimentally demonstrated that the block punch test is as useful as the point load test in predicting the UCS of rocks. They also evaluated the effectiveness of existing empirical equations for predicting UCS with the block punch index. They concluded that the prediction of Brazilian tensile strength by the block punch index is more accurate than the point load strength. Some researchers have correlated the results of the indentation test with the UCS of rocks. Szwedzicki (1998)

[0024] proposed a standardized indentation test as a measure of rock hardness and its use as a predictor for UCS. Another method of measuring strength by penetration is the Windsor probe, which was developed in the 1960s to measure the compressive strength of concrete in situ. This "less destructive" test is a type of hardness strength test used to determine the compressive strength of concrete in a short time. This technique is based on the relationship between the compressive strength and the depth of penetration measured by driving a special probe into the concrete. Material hardness is measured according to the Mohs scale. It has been reported that the calibration chart provided with the setup does not always give reliable results (Malhotra and Carino, 1991

[0015] ; Pucinotti, 2005

[0020] ; Pucinotti, 2009

[0021] ). Although the experimental technique is characterized as "non-destructive", it is considered to be partially destructive.

[0015] The Korean Patent No. KR20100108852A, which is in the state of the art, mentions a spiral grooved swivel bolt used in conventional pistols.

[0016] When the existing studies in the art were examined, it was necessary to develop the inventive nail gun, which provides easy measurement of the compressive strength of materials such as rock, concrete and brick, is portable and has zero destruction rate. Objectives of the Invention

[0017] The purpose of this invention is to realize a portable nail gun with zero destruction rate, which enables easy measurement of the compressive strength of materials such as rock, concrete and brick.

[0018] A further object of the present invention is the realization of a nail gun for measuring material strength without the need for coring.

[0019] A further object of the present invention is the realization of a nail gun that allows the strength of concrete components of an old structure to be tested against earthquakes to be carried out in situ and non-destructively.

[0020] Detailed Description of the Invention

[0021] The nail gun realized to achieve the objects of the present invention is shown in the accompanying figures.

[0022] These figures are;

[0023] Figure 1: Schematic view of a nail gun for measuring the strength of the inventive material.

[0024] Figure 2: A schematic view of a nail gun for measuring the material strength of the invention, with the barrel and body separated from each other.

[0025] The parts in the figures are individually numbered and the corresponding numbers are given below.

[0026] 1. Body

[0027] 2. Grip

[0028] 3. Needle setting piston

[0029] 4. Needle setting spring

[0030] 5. Trigger

[0031] 6. Trigger protection mechanism 7. Ignition needle

[0032] 8. Needle slot screw

[0033] 9. Needle impact spring

[0034] 10. Body fixing bearing

[0035] 11. Bullet

[0036] 12. Bullet holster

[0037] 13. Barrel

[0038] 14. Inner barrel bed

[0039] 15. Inner barrel safety spring

[0040] The invention relates to a portable and non-destructive nail gun for easy measurement of the compressive strength of materials such as rock, concrete and brick, comprising the parts

[0041] - Body (1),

[0042] Grip (2) under the receiver (1) for holding the pistol,

[0043] Trigger (5) located in the housing (1),

[0044] - Needle setting spring (4) in connection with trigger (5),

[0045] - Needle setting plunger (3) located in the housing (1) and pulled outwards from the housing (1) to tension the needle setting spring (4),

[0046] Trigger protection mechanism (6) located under the receiver (1), which surrounds the trigger (5) and protects the trigger (5),

[0047] The firing pin (7) is located in the body (1) and detonates the bullet (11),

[0048] - Needle slot screw (8) in connection with the firing pin (7),

[0049] - Needle impact spring (9) located on the firing pin (7),

[0050] - Barrel (13) screwed to the body (1),

[0051] - Movable cartridge case (12) in the barrel (13) holding the sound (dummy) bullet (11),

[0052] The inner barrel bearing (14) located inside the barrel (13),

[0053] Inner barrel safety spring (15) located at the end of the barrel (13).

[0054] The nail gun measuring material strength of the invention is capable of shooting nails with diameters of 4 mm, 5 mm and 6 mm. The nails are made of special steel and heat treated. Sound (dummy) bullets (11) are used to drive the nails into the test material. The energy of standard sound bullets (11) is determined as 150 Joules. In the nail gun according to the invention, bullets (11) with a two-thirds reduction in the amount of gunpowder and an energy of 50 J can be used for low-strength building materials. In this way, the compressive strength of all kinds of building materials with strengths between 1-100 MPa can be determined. The strength of the tested building material is calculated with the help of formula I.[8] (Formula I)

[0055] Where; accompressive strength (MPa), : nail diameter (mm), h: nail penetration depth (mm) and E: energy (N.m or Joule) produced by the sound (dummy) bullet (11). The penetration depth of the nail is measured at the end of the hammering by detonating the sound bullet (11) on the flat surface of the building material. The length of the nails is 60 mm. The outside of the nail is measured by means of a vernier and the penetration depth of the nail is calculated by subtracting this value from 60 mm. Preferably 5 shots will be recommended for compressive strength. If the block size of the material to be shot is small, at least 3 shots will be made and the average will be taken after subtracting the lowest and highest penetration values.

[0056] During the use of the nail gun subject to the invention, in the first step, one of the heat-treated nails with a diameter of 4, 5 and 6 mm and a length of 60 mm, sharpened at a certain angle, is inserted into the nail fixing cap with the other (threaded) side of the nail with the pointed side of the nail towards the end of the barrel (13). In order to prevent the nail from falling out of the fixing sleeve when the gun is brought in the direction of gravity, the nail is fixed into the fixing sleeve with the threads on the non-pointed side of the nail. In order to prevent the nail and the fixing sleeve from falling with the nail due to the effect of gravity, O-ring rubber is put around the nail fixing sleeve to prevent the nail and the fixing sleeve holding it from falling. The nail and the cap that holds it are driven into the barrel (13) before the cartridge case (12) that holds the sound bullets (11). In the second step, the sound bullet (11) is inserted into the movable cartridge case (12). The cartridge case (12) is gently pressed down and the nail (with cap) is driven into the barrel (13). In this case, the lower part of the live cartridge case (12) and the upper part of the nail head are in full contact.

[0057] After completing these two steps, the barrel (13) of the nail gun is inserted into the housing fixing seat (10). This is done by rotating the barrel (13) 5 turns by engaging the gears at the rear of the barrel (13) with the gears in the body (1).

[0058] When the barrel (13) is inserted into the chamber, the fuse side of the sound bullet (11) is in full contact with the firing pin (7). An internal barrel safety spring (15) is provided at the end of the barrel (13) to ensure that the nail gun fires only in the firing position. In order to fire the nail gun into a material such as stone, brick or concrete, when the gun is in the vertical position, the inner piston presses the sound bullet (11) against the firing pin (7) by means of the inner barrel safety spring (15). During this process, the firing pin (7) is slightly tensioned.

[0059] The needle setting plunger (3) is pulled outward by hand and the needle setting spring (4) is tensioned.

[0060] The trigger (5) is pulled, causing the needle setting piston (3) to strike the back of the needle setting piston (3) and the firing pin (7) to strike the back of the sound bullet (11). The resulting pressure drives the nail with its head into the target or (if the material is very strong) makes a dent in the target surface. The strength of the material is then measured using the information mentioned above.

[0061] The smaller diameter of the nail used by the pistol and the pointed tip means that there are no cracks around the point where the nail is inserted. In this context, a completely non-destructive test method is realized.

[0062] In order to keep the nail and its head in the barrel (13) in a vertical position without falling out, the nail head is fitted with an O-ring (a round rubber ring) which provides a slight friction inside the barrel (13). O-rings of all diameters and wall thicknesses are available from rubber manufacturers at very low cost. In this sense, it is more economical.

[0063] In the pistol according to the invention, the barrel (13) and receiver (1) are connected to each other by means of conventional threads of 5 turns. The connection of the two parts in a plug-and-play manner provides a significant advantage in terms of the service life of the invention.

[0064] When the nail gun of the invention is leaning against the target, the inner barrel chamber (14) is pushed back and the end of the sound bullet (11) comes into contact with the firing pin (7). In this case, even if the trigger (5) is pulled, firing is not possible. In order for firing to occur, the needle setting piston (3) must be pulled out of the chamber and tension the needle setting spring (4). Firing is only possible in this way.

[0065] References:

[0066] [1] Aoki, H., Matsukura, Y. 2008. "Estimating the unconfined compressive strength of intact rocks from Equotip hardness", Bulletin of Engineering Geology and the Environment 67, 23-29.

[0067] [2] ASTM. 1995. "Standard test method for determination of the point load strength index of rock", ASTM Standard 05731.

[0068] [3] ASTM. 2001. "Standard test method for determination of rock hardness by rebound hammer method", ASTM Standard 05873.

[0069] [4] ASTM. 2002. "Standard test method for unconfined compressive strength of intact rock core specimen", ASTM 02938.

[0070] [5] Bae, G. J., Lee, S. W., Chang, S. H., Park, H. G., Lee, M. S., Kim, J. K. 2004. "Application ofpneumatic pin penetration test to estimation of compressive strength of shotcrete in Korea", Tunnelling and Underground Space Technology, 19, 432- 440. [6] Bieniawski, Z. T. 1975. "Point load test in geotechnical practice", Engineering Geology, 9(1), 1-11.

[0071] [7] Broch, E., Franklin, J. A. 1972. "Point-load strength test", International Journal of Rock Mechanics and Mining Sciences, 9(6), 241-246.

[0072] [8] Oakdale Engineering, 2008, DATAFIT: Version 9.0, RC 101, 23 Tomey Road, Oakdale, PA, 15071 USA.

[0073] [9] Felicetti, R., Gattesco, N. 1998. "A penetration test to study the mechanical response of mortar in ancient masonry buildings". Materials and Structures. 31(5), 350-356.

[0074]

[0010] ISRM. 1978. "Suggested method for determining hardness and abrasiveness of rocks", International Journal of Rock Mechanics and Mining Sciences, 15, 89-97.

[0075]

[0011] ISRM. 1985. "Suggested method for determining point-load strength", International Journal of Rock Mechanics and Mining Sciences, 22, 53-60.

[0076]

[0012] Kayabah, K., Selcuk, L. 2010. "Nail penetration test for determining the uniaxial compressivestrength of rock", International Journal of Rock Mechanics and Mining Sciences, 47, 265-271.

[0077]

[0013] Li, X., Rupert, G., Summers, O. A., Santi, P., Liu, O. 2000. "Analysis of impact hammer rebound to estimate rock drillability", Rock Mechanics and Rock Engineering, 33, 1-13.

[0078]

[0014] Liberatore, O., Spera, G., Cotugno, M. 2003. "A new penetration test on mortar joints", On-site Control and Evaluation of Masonry Structures, 191-202.

[0079]

[0015] Malhotra, V. M., Carino, N. J. (eds.). 1991. "Handbook on nondestructive testing of concrete", Boca Raton, FL, CRC Press, 384 pp.

[0080]

[0016] Maruto Corporation. 2006. "Penetrometer for soft rock: Model SH-70 instruction manual".

[0017] Mishra, O. A., Basu, A. 2012. "Use of the block punch test to predict the compressive and tensilestrengths of rocks", International Journal of Rock Mechanics and Mining Sciences, 51, 119-127.

[0081]

[0018] Ngan-Tillard, O. J. M., Verwaal, W., Mulder, A., Engin, H. K., Ulusay, R. 2011. "Application ofthe needle penetration test to a calcarenite, Maastricht, the Netherlands", Engineering Geology, 123(3), 214-224.

[0082]

[0019] Palassi, M., Emami, V. 2014. "A new nail penetration test for estimation of rock strength", International Journal of Rock Mechanics and Mining Sciences, (66), 124-127.

[0083]

[0020] Pucinotti. R. 2005. "Non destructive testing in the valuation of reinforced concrete structural degradation", L'lndustria Italiana del Cemento. 810. 446-460.

[0084]

[0021] Pucinotti, R. 2009. "in situ concrete strength assessment: Influence of the aggregate hardness on the Windsor probe test results", Journal of Building Appraisal, 5(1), 75-85.

[0085]

[0022] Selguk, L., Kayabali, K. 2015. "Evaluation of the unconfined compressive strength of rocksusing nail guns", Engineering Geology; 195(3), 164-171.

[0086]

[0023] Selguk, L., Coban, S., Kayabali, K., Sim§ek, O. 2012. "A non-destructive testing technique: Nail penetration test", ACI Structural Journal, 109(2), 245-252.

[0087]

[0024] Szwedzicki, T. 1998, "Indentation hardness testing of rock", International Journal of Rock Mechanicsand Mining Sciences, 35, 825-829.

[0088]

[0025] Ulusay, R., Gokceoglu, C., Sulukcu, S. 2001. "Draft ISRM suggested method for determining block punch strength index (BPI)", International Journal of Rock Mechanics and Mining Sciences, 38, 1113-1119.

[0089]

[0026] van der Schrier, J. S. 1988. "The block punch index test", Bulletin of the InternationalAssociation of Engineering Geology 38, 121-126.

[0027] Verwaal, W., Mulder, A. 1993. "Estimating rock strength with the Equotip hardness tester", International Journal of Rock Mechanics and Mining Science Geomechanics Abstracts 30, 659-662.

[0090]

[0028] Yilmaz, I. 2009. "A new testing method for indirect determination of the unconfined compressive strength of rocks", International Journal of Rock

[0091] Mechanics and Mining Sciences, 46, 1349-135757.

[0092]

[0029] Yilmaz, I., Sendir, H. 2002. Correlation of Schmidt hardness with unconfined compressivestrength and Young's modulus in gypsum from Sivas (Turkey)", Engineering Geology, 66, 211-219.

Claims

CLAIMS1. The invention relates to a portable and non-destructive nail gun for easy measurement of the compressive strength of materials such as rock, concrete and brick, characterized by comprising the partsA body (1),A trigger (5) located in the housing (1),A needle setting spring (4) in connection with trigger (5),A needle setting plunger (3) located in the housing (1) and pulling outwards from the housing (1) to tension the needle setting spring (4),A firing pin (7) located in the body (1) and detonates the bullet (11), A needle slot screw (8) in connection with the firing pin (7), A needle impact spring (9) located on the firing pin (7),A barrel (13) screwed to the body (1),An inner barrel bearing (14) located inside the barrel (13),An inner barrel safety spring (15) located at the end of the barrel (13).

2. The invention relates to a nail gun according to claim 1, characterized in that it comprises a grip (2) located below the body (1) for holding the gun.

3. The invention relates to a nail gun according to claim 1, characterized in that it comprises a trigger protection mechanism (6) located below the body (1) and wrapping around the trigger (5) to protect the trigger (5).

4. The invention relates to a nail gun according to claim 1, characterized in that it comprises a movable cartridge case (12) located in the barrel (13) and holding the sound bullet (11).

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