KR101249996B1 - Apparatus and method for free falling impact test - Google Patents

Abstract

The present invention is to provide a free falling impact tester (Free falling impact tester) and a free falling impact test method using the same falling freely while the falling test object is initially set the falling posture until the drop collision.

Free fall, impact test

Description

Apparatus and method for free falling impact test

The present invention relates to a drop impact test method and apparatus for performing a drop impact test of portable electronic products such as mobile phones, electronic dictionaries, personal computers, etc., and can be set quantitative drop control by simple operation without expensive auxiliary equipment. The present invention relates to a free fall impact test method and apparatus having reliability.

In order to develop expensive portable electronics to prevent malfunctions due to inadvertent dropping, each set-maker performs drop impact tests assuming all dropping situations that may occur in actual phenomena at the product development stage. To this end, we are attempting to mechanize the drop impact test equipment with reproducibility and reliability. As it turns out that there is a significant difference in the amount of impact energy received by portable electronic products according to the incident angle during the drop, we are conducting drop impact tests of various drop angles for reliable product development. . In the conventionally known technology, the dropping material is transferred to a predetermined height by using a mechanism for adjusting the dropping posture and a keying piece for adjusting the dropping height, and then free-falling on the bottom surface of the drop and freely falling using various sensors. Determine the extent of the damage.

1. Quantitative attitude control problem

The quantitative setting of the falling posture is a three-dimensional shape of the falling object (if the vertical direction in which the falling object is a z-axis refers to the two axes constituting the drop impact plane, the x-axis and the y-axis), Configuration variables required. That is, set the drop height (h _z) and dropping each rotation angle values for the two spatial coordinate axes defining the impact surface (defined as the rotation angle φ _y of the angle of rotation φ _x and y axes of the x-axis) It cannot be controlled quantitatively except two heights (JP1989-316630, JP2000-065677, JP2000-111464, JP2002-372486, JP2003-215006, JP2003-166922, KR10-2004-0006510, JP2005-030938). , US6508103). In addition, since the drop posture cannot be precisely and quantitatively controlled, there is a problem that it is difficult to design a sensitivity according to the drop angle, and it is difficult to perform a reliable repeat test.

2. Second collision behavior problem

The falling object collides with the fall floor more than two times as it rebounds after the first impact on the impact floor. At this time, the first collision point is intended by the experimenter, but the second collision point caused by the bounce is not expected by the experimenter because the falling object causes the translational and rotational movements due to the impact reaction and the inertial effects of the falling object. In some cases, the crash behavior after the first collision is also very important, as the falling objects can sometimes be seriously damaged at the secondary collision site.

However, if a separate mechanism is used to maintain the falling posture (JP1989-316630, JP2000-065677, JP2000-111464, JP2002-372486, JP2003-166922, JP2005-030938), the first collision is caused because the falling object is constrained to the apparatus. Thereafter, there is a problem that the collision behavior is difficult to occur naturally. Even in a system for opening a falling object from an object to maintain a posture immediately before falling (US6508103, JP2003-166922, JP2002-372486, and JP2005-030938), if the falling object has a high rebound height, the falling object is placed on the posture holding device. There is a possibility of being hit.

3. Posture maintenance problem after opening

Considerations for free fall are the center of gravity (C.G.) of the falling object and its relative position to the center point of the fixture holding the falling object. If the vertical line passing through the center of gravity of the falling object and the vertical line passing through the center point of the fixture holding the falling object do not coincide, the falling object has a rotational motion due to the distance difference between the two points. That is, when the point of the instrument and the center of gravity of the falling object do not coincide (US6508103, JP2003-166922), the falling posture may not be maintained at the same time as the inertia of the falling object is opened (Fig. 2). ).

When a stopper is used to open the falling object (JP2002-372486, KR10-2004-0006510), when the impactor hits the stopper at the free fall speed, an inertial reaction may occur and the falling object may shake. In the case of releasing the falling object by opening the tong-shaped jig by using an external signal (US6508103, JP2007-163222), it is difficult to find the release time for the falling object. There is a problem that can be shaken.

4. Flexibility of equipment on falling object shape

In the case of using a fixed auxiliary device other than a thread or a string to maintain the falling posture of the falling object (US6508103, JP2007-163222), it is difficult to easily accommodate the variability according to the shape, size and weight of the test object.

5. Complexity and Price Rise of Equipment

When using a mechanism such as a guide rail (Guide rail) to maintain the posture, the guide rail must also be a high-speed drive, there is a problem that the equipment is complicated and the manufacturing price rises. Recently, a device for opening a falling object by using an electrical signal has been developed, but the use of expensive precision measuring equipment has a disadvantage in that the equipment is complicated with an increase in manufacturing cost.

Table 1 shows related patents by function.

posture
Controlled Falling objects
Open Stopper opening JP2000-111464 (US6374661) Clamp-type jig opening US6508103 (JP2003-502630)
JP2007-163222 (KR10-2007-0079355) Falling objects
Non-open With guide rail JP2000-65677
JP2002-372486
JP2005-30938 (US6892564) Visa
Controlled Falling objects
Open Stopper opening KR10-2004-0006510 Falling objects
Non-open With guide rail JP1989-316630 Etc JP2003-166922

KR10-2004-0006510 includes a holder for fixing and dropping a mobile terminal, a guide for guiding the vertical movement of the holder, an upper motor fixed to the top of the guide to raise the holder to a certain height, and fixed to the holder In the drop test apparatus of the mobile terminal comprising a shock surface fixed to the bottom of the guide so that the mobile terminal to be separated after the height drop collides, and a fixed frame for fixing the impact surface and the upper motor portion at a certain height, the impact surface The drop test apparatus of the portable terminal is configured to be separated from the fixed frame to be dust-proof.

KR 10-2008-0090170 includes a base plate for causing a test object to be dropped to be dropped in a state of maintaining a desired posture, and providing a horizontal plane; A height adjusting pillar fixed to the base plate and extending vertically; An arm supported by the height adjustment pillar and vertically movable and extending laterally of the height adjustment pillar; Arm fixing means for fixing the arm to the height adjustment pillar; A free drop test apparatus is disclosed that includes an object holder that is connected to the arm in a desired posture and detachably attached to the arm, and that is detached from the arm during the drop test and falls down to the base plate with the object under test.

JP1989-316630 includes a drop tester capable of repeatedly dropping an article on a falling surface at a constant height position and checking the durability against the impact of the article by measuring the number of drops until the article is destroyed; A string-like body for coupling one end to the article and fixing the other end to the fixing portion, while passing the middle portion through the guide member fixed at a certain height position; Engaging means for disengaging engagement of the string-like body at an intermediate portion between the guide member and the fixed end; Moving means for movably supporting the engagement means; An article detecting means for detecting the presence or absence of the article when moving the moving means and pulling up the article bonded to one end of the string-shaped body engaged with the engaging means; Counting means for counting the number of times of detection by the article detecting means; The counting means, the engaging means and the control means for controlling the moving means, based on the operation start command, driving the engaging means to engage the string body, and then driving the moving means to engage the engaging portion with the cord-shaped article upwards. After moving and lifting the article to a certain height, the article can be naturally dropped by detaching the string body engaged with the engaging means, and the above-described operation is repeated once again by returning the moving means to the original position, A drop tester having control means for performing repeated control until an article is not detected by the detection means is disclosed.

JP2000-65677 includes a drop test apparatus which executes a drop test by dropping a test object from a height together with a holder along a drop guide rail using a holder held by a string-like material and held in an arbitrary position. Is disclosed.

JP2000-111464 (US6374661) includes a) means for suspending an object at a predetermined angle, b) means for dropping the object and suspending means with substantially no relative movement, and c) impacting as a result of the object falling. A drop test apparatus is disclosed that includes a means for substantially opening in a state suspended from a means to suspend an object at some point before receiving.

JP2002-372486 has an arm for supporting a thin hanging line for hanging a test object, a guide rail for guiding the arm, a collision surface where the test object collides, and an arm stopper for stopping the drop of the arm at a predetermined position. The drop test apparatus which can drop a test object as it is hanging on an arm, and makes it collide with a collision surface WHEREIN: The fall test apparatus provided with the shake prevention mechanism which prevents the shake of a test object is disclosed.

JP2003-166922 has a drop impact test apparatus capable of dropping a test object in a state supported by a holder, and performing a drop impact test by colliding the test object with the impact support plate, wherein the holder has a taper having an inclined portion for supporting the test object. The drop impact test apparatus provided with a part is disclosed.

JP2003-215006 includes an apparatus main body supported by elevating means for lifting and lowering by being supported by elevating means in a drop test, by suspending and supporting the object under test. A first position disposed opposite each other, the intermediate portion being supported by the apparatus body by a horizontal axis, the upper ends approaching each other and the lower ends being spaced apart from each other, and the upper ends being spaced from each other The lower end rotates between the second positions approaching each other, and at the same time, each pair of arms in the first position; A cylinder located above the pair of arms and installed in the apparatus body for elevating the piston along a vertical direction to approach and space the pair of arms; A spacer which is installed in the piston of the cylinder and is inserted between the upper portions of the pair of arms when the piston descends, and fixes the pair of arms in the second position; Disclosed is a drop test apparatus having a suspension tool that is suspended from a test subject and supported by a pair of arms pivotably on a horizontal axis when the pair of arms are in a second position.

JP2005-30938 (US6892564) includes an elevating member for elevating an inspection object holding member to be tested for drop strength at an arbitrary posture angle, and an elevating member for elevating the inspection object holding member to which the inspection object is fixed in the falling direction of the inspection object. And a fall target bottom configured to collide with the inspected object only at the end of the drop direction without interfering with the lift member when the elevating member falls simultaneously with the inspective fixing member, and the inspective fixing member is non-adhesive to the lifting member. A drop test apparatus is disclosed in which a holding member is detachable from a lifting member when supported and the test object collides with the floor to be dropped.

JP2007-163222 (KR10-2007-0079355) uses a drop test platform, a PCB, an image pickup card, an impact accelerometer, a clamping device, and a CCD camera to acquire an object to be measured, and to measure the object to be measured. Setting, suspending the workpiece under the frame by the clamping device, starting the operation of the clamping device with the monitor program, placing the workpiece in the clamping device, freely dropping the workpiece, and placing the workpiece under the piezoelectric sensing platform. The drop test measurement method which falls on and compares a simulation value and an experiment is disclosed.

US6508103 (JP2003-502630) includes a clamping mechanism for supporting a product to be tested, a guideway, a sliding part mounted to slide along the guideway and to move the device toward a target position, and to release the product from the device. A drop test apparatus having a release device for impinging on a target position is disclosed.

The present invention relates to the problem of quantitative attitude control of falling objects as described above, the problem of natural sequential impulse after the first collision, the problem of maintaining the falling attitude after opening the falling object, the flexibility of the equipment to the shape of the falling object, and the complexity and price increase of the equipment. To solve the problem, and to provide a simple and low cost drop impact test method and apparatus.

In addition, the present invention is to set the drop posture quantitatively to solve the above problems, implement the ideal drop collision behavior by dropping the drop test object unconstrained anywhere, and adjusts so that rotation inertia does not occur during the fall It is an object of the present invention to provide a drop impact test method and apparatus, which enables precise repeated testing.

In order to achieve the above object, the present invention comprises the steps of: (a) measuring the weight of the falling object to determine the strength of the connection line connecting the falling object fixing support and the falling object at the top of the drop impact test apparatus; (b) setting the x, y and z axes in space for the falling object; (c) measuring the longest length ( L _x , L _y ) with respect to the length and width direction of the falling object, respectively; (d) setting the total length l _x , l _y of the connecting line of the falling object with respect to the selected axis in the length and width directions, respectively; (e) Determine the center of gravity ( X _cg , Y _cg ) of the falling object that coincides with the center of gravity ( x _cg , y _cg ) of the connecting line on any two plane axes, and then connect the height of the connecting line perpendicularly from the center of gravity of the falling object ( measuring and recording the left and right lengths ( l ⁰ _xL , l ⁰ _xR , l ⁰ _yL , l ⁰ _yR ) of the connecting line based on the upper vertex of l _z ); (f) Rotate the falling object at any angle using the posture setting device, and measure the left and right lengths ( l ^{θ '} _xL , l ^θ' _xR , l ^θ _yL , l ^θ _yR ) of the connecting line in the rotated state, respectively. Post-recording; (g) dropping the falling object using the falling object detachment device after mounting the fixed support using the connecting wire so that the attitude of the falling object is maintained according to the test condition using the determined connection line length information; (h) recording the impact of the falling object on the floor using a moving image photographing apparatus; And (i) storing the acceleration magnitude of the falling object obtained from the falling object and the falling impact amount collected from the falling impact surface by using the data collection device and analyzing the falling impact amount.

In the present invention, in order to determine the center of gravity of the falling object in step (e), by inserting a circular bar between the x-axis connecting line connecting the falling object, by lifting the bar at any position between the connecting line, L _x ) is the base and the end of the bar forms a triangle with its vertices facing the base, and the rotation of the bottom of the drop is parallel to the x-axis or the y-axis, moving the position of the bar between the connecting lines. After finding the position where the angle φ _y is 0, the center of gravity is identified by calculating or marking the falling object with a laser pointer, and the center of gravity of the falling object is determined by performing the same method as the x axis with respect to the y axis. It is done.

In the present invention, the center of gravity of the falling object ( X _cg , Y _cg ) can be calculated by the following equation (1).

(Where X _cg = x _{cg and} Y _cg = y _cg )

In the present invention, the total length of the connecting line is correlated with the longest length of the falling object in the following Equation 2, and the left and right lengths of the connecting line are correlated with the following Equation 3.

l _x = C ₁ × L _x

l _y = C ₂ × L _y

(C _1, C ₂ is a constant greater than _{1, C 1, C 2 ≥} 1.5)

l _x = l ⁰ _xL + l ⁰ _xR = l ^{θ '} _xL + l ^θ' _xR

l _y = l ⁰ _yL + l ⁰ _yR = l ^θ _yL + l ^θ _yR

As the present invention the weight center point of the falling object (X _cg, Y _cg) and the center of gravity (x _cg, y _cg) of the connecting line matching, characterized in that the free rotation by the rotational inertia of the free-fall upon falling objects is prevented.

In addition, the present invention is placed on the floor and the base plate to collide with the falling object to be tested; A pillar fixed to the base plate and installed in a vertical upper portion; Falling object fixing support is installed in the horizontal direction to the height adjustable on the top of the column, fixing the falling object; A falling object connecting line connecting the falling object fixing support and the falling object; A falling object detachment apparatus for detaching and falling the falling object from the falling object fixing support; A falling object acceleration sensor attached to the falling object and measuring the acceleration of the falling object; An impact amount sensor mounted on the bottom surface of the substrate to measure an impact amount of the falling object; A falling behavior video recording apparatus for photographing falling behavior of falling falling objects; And a data collecting device connected to a falling object acceleration sensor, an impact amount sensor, and a falling motion video photographing device to collect and analyze measurement data.

The drop impact test apparatus of the present invention may further include a posture setting device for setting the falling posture of the falling object at a desired angle.

In the present invention, the posture setting device includes a base plate located below; A height of the connection line installed on the base plate so as to move left and right, and connecting the connection line so that the height can be adjusted; An auxiliary base plate hinged to one side of the base plate to move at an angle with the base plate to accommodate falling objects; An angle adjuster and an indicator installed at a coupling portion of the base plate and the auxiliary base plate to adjust the angle of the auxiliary base plate and display the angle; A guide for moving the left and right connecting lines installed at the coupling portion of the base plate and the pillar to move the pillar from side to side; And an angle holder which is installed at a joining portion of the base plate and the auxiliary base plate and fixes the auxiliary base plate after the auxiliary base plate has a predetermined angle to maintain the angle.

In the present invention, the base plate is a frame in the form of a box having an upper portion and a plurality of grooves for receiving the impact amount sensor in the lower portion; A variable drop impact plate which is detachably seated on an upper portion of the frame, and which has a falling surface colliding with a falling object in various forms; And an impact plate detachment preventing device installed horizontally inward on the upper portion of the frame to prevent the impact plate from being separated.

In the drop impact test apparatus of the present invention, the drop material desorption apparatus may be electric, pneumatic, electromagnet or spring type.

The free fall test apparatus of the present invention can set the drop posture quantitatively at low cost, and implement the ideal drop collision behavior by dropping the drop test article unconstrained anywhere, and does not cause rotational inertia during the drop. This allows precise repeat testing.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a configuration diagram of a free-fall impact test apparatus according to the present invention, the base plate 1, the dropping device support and height adjustment pillar (2), the fixed support (3), the falling object connecting line (4), the falling object desorption device ( 5), a falling object acceleration sensor 6, an impact amount sensor 7, a falling motion video photographing device 8, and a data collecting device 9.

The base plate 1 supports the whole apparatus including the falling surface on which the falling object which collides with a test object collides. The base plate may be provided with a detachable variable drop plate (Variable drop plate) that can consider a variety of falling surface, it is possible to be transmitted to the falling base surface without the impact amount of the variable falling surface.

9 is a configuration diagram of the base plate 1, wherein the base plate 1 is fixed to the frame 21, the variable drop impact plate 22, the impact plate detachment preventing device 23, the impact amount sensor 24 and the impact amount sensor. The groove 25 is provided.

The frame 21 has a box-like structure having a plurality of grooves 25 for opening the upper portion and receiving the impact amount sensor 24 in the lower portion.

The variable drop impact plate 22 is detachably seated on the upper portion of the frame 21, and the upper and lower surfaces of the upper surface which collide with the falling object may be changed in various forms.

The impact plate detachment preventing device 23 extends in a straight shape to be inward in the horizontal direction on the upper rectangular frame of the frame 21 to prevent the impact plate 22 from being separated.

In order to measure the impact amount of the falling object, a load cell (load cell) is installed on the bottom surface of the frame 21 of the base plate 1, and a variable impact plate 22 is placed on the installed load cell. The bottom surface of the frame 21 is made of steel, and the load cell must be completely fixed to the bottom surface. The drop impact plate 22 and the load cell should also be sufficiently in contact with each other so that the drop impact amount is transmitted to the load cell without loss, and the shake of the drop impact plate 22 due to the drop impact of the falling object should not occur.

Since there are usually threads in the load cell, in consideration of this, as the groove 25 in the bottom surface of the frame 21, a plurality of screw holes capable of assembling the load cell are processed. Rather than installing one in the center of the load cell, it is preferable to install three at regular intervals so that the drop impact plate 22 does not shake. In addition, the outside of the bottom surface of the frame 21 to make a rectangular frame of a certain size to help the mounting of the drop impact plate (22). The gap between the outer frame of the frame 21 and the drop impact plate 22 is filled with a cushioning material such as rubber so as not to shake up, down, left and right. The drop impact plate 22 may vary in size and material so as to consider the size of the falling object and the drop impact situation, the material used may be considered wood, concrete, asphalt, etc. (FIG. 9).

The pillar 2 is fixed to the base plate 1 and installed in the vertical upper portion, and supports the drop impact test apparatus while fixing the fixed support 3 so that the height can be adjusted.

The falling object fixing support 3 is fixed on the one side of the top of the column 2 in the horizontal direction, the other side to fix the falling object. Falling object fixed support 3 may be fixed to the height adjustable. For example, as disclosed in Korean Patent Laid-Open Publication No. 2008-90170, a plurality of holes are formed in the pillar 2 at regular intervals, and the fixing support 3 having a hole corresponding to the hole of the pillar 2 is provided. Put the column 2, the fixed support (3) is moved to the desired height, the holes of the column (2) and the fixed support (3) can be aligned, and then can be fixed by inserting a pin into the hole.

The falling object connecting line 4 connects the falling object fixing support 3 and the falling object, and is made of, for example, a thread or a string such as a silk thread, a fishing line, and a piano string. The reason for selecting the connecting line 4 as the same kind of thread is to ensure free impact behavior of the falling object. The strength of the connecting line 4 can be determined according to the weight of the falling object.

The falling object detachment apparatus 5 is a device which detaches and falls a falling object from the falling object fixing support 3, and is an apparatus which opens a falling object with the falling attitude set for a test. The falling object detachment apparatus 5 may be made of an electric, pneumatic, electromagnet or spring type. For example, after attaching a detachable pin to one side of the falling object fixing support 3 and covering the connecting line 4 to the pin, the falling object can be dropped by opening the pin. In addition, as disclosed in Korean Patent Laid-Open Publication No. 2008-90170, by using a holder member for connecting the fixed support 3 and the connecting line 4, the holder member is detachably installed on the fixed support 3 with a pin. After that, the pin can be opened to drop the falling object.

Falling object acceleration sensor 6 is attached to the falling object for quantitative analysis of the drop test to measure the acceleration of the falling object.

The impact amount sensor 7 is a piezoelectric sensor that is mounted on a drop base frame of the substrate to measure the drop impact amount of the falling object dropped for the quantitative analysis of the drop test.

The falling behavior video photographing apparatus 8 is a device for photographing the falling behavior of falling objects falling, and photographs the falling collision process using a camera.

The data collecting device 9 is connected to the falling object acceleration sensor 6, the impact amount sensor 7, and the falling motion video photographing device 8 to collect and analyze the measurement data. DAQ (Data acquisition system) system.

7 is a configuration diagram of a posture setting device for setting a falling object at an arbitrary angle, wherein the posture setting device includes a base plate 11, a connecting line height adjusting pillar 12, an auxiliary base plate 13, an angle adjuster, and an indicator 14. ), A connecting line 15 for moving left and right, and an angle holder 16.

The base plate 11 is located under the posture setting device.

The connecting line height adjusting pillar 12 is installed vertically on the base plate 11 so as to be movable left and right, and connects the connecting line 4 so that the height can be adjusted. Height adjustment of the connecting line 4 can be implemented in the same manner as the height adjustment method of the fixed support (3) as described above.

The auxiliary base plate 13 is hinged to one side of the base plate 11 to move at an angle with the base plate 11 to accommodate the falling object on the upper surface.

The angle adjuster and the indicator 14 are installed at the bonding portion of the base plate 11 and the auxiliary base plate 13 to adjust the angle of the auxiliary base plate 13 and display the angle.

The guide line left and right movement guide 15 is installed at the coupling portion of the base plate 11 and the pillar 12 to move the pillar 12 to the left and right, thereby adjusting the left and right positions of the connection line 4. For the left and right movement, for example, sliding doors, rails are installed on the base plate 11 and wheels are mounted on the guides 15, so that the guides 15 slide on the rails.

The angle holder 16 is installed at the joining portion of the base plate 11 and the auxiliary base plate 13, and after the auxiliary base plate 13 is at an angle, the auxiliary base plate 13 is fixed to maintain the angle. Let's do it.

Hereinafter, the drop impact test method using the drop impact test apparatus according to the present invention will be described.

First, the weight of the falling object is measured to determine the strength of the connecting line. The strength of the connecting line is determined safely, such as a rope, fishing line, parachute or piano string, taking into account the weight of the falling object. It is preferable that the length ( l _x , l _y ) of the connecting line is sufficiently longer than the longest length of the falling object. It is recommended that at least 1.5 times the longest length of the falling object be attached, and that the two connecting lines have the same height ( l _z ) when the falling object is attached with two connecting wires.

&Quot; (2) "

l _x = C ₁ × L _x

l _y = C ₂ × L _y

Where C ₁ and C ₂ are constants greater than 1 ( C ₁ , C ₂ ≥ 1.5 is recommended)

Next, as in FIG. 3, the x, y and z axes in space for the falling object are set. The falling objects are naturally placed on the drop impact plane and the orthogonal plane axes x and y are set in consideration of the test purpose.

Next, if the plane axes x and y are set, the longest length of the falling object in the axial direction is measured ( L _x , L _y ). That is, as shown in FIG. 4, the longest lengths L _x and L _y in the length and width directions of the falling object are measured, respectively.

Next, as shown in FIG. 4, l _y and l _x, which are connecting line lengths of the falling object with respect to the selected axis in the length and width directions, are respectively determined.

Next, as shown in Figs. 4, 5, and 6, the center of gravity (CG) is determined to be parallel to the falling surface on any two plane axes. Center of gravity Two coordinate values ( x _cg , y _cg ) are taken sequentially.

If the center of gravity of the falling object (X _{cg, cg} Y) and the center point (x _cg, y _cg) of the machine (connection line) matches, falling objects is to maintain a parallel orientation with a drop impact surface. The center of gravity of the falling object is obtained as follows.

If the center of gravity of the x-axis, X _cg, is found first, attach the x-axis connecting line ( l _x ) to the falling object parallel to the x-axis at any position on the x-axis line. The length of the connecting line should be prepared considering the diameter of the rod used. Even if you want to wind the connecting line several times to prevent slipping, the length of the absolute distance divided by the bar should always be equal to the initial set length ( l _x ), taking into account the wound length.

Insert a circular rod between the x-axis leads and lift the drop. After attaching the connecting line, if the bar is lifted at any position between the connecting lines, a triangle is formed in which the x-axis length L _x of the falling object becomes the base and the end of the bar becomes a vertex facing the base. While moving the position of the bar between the connecting line to find the position where the base is parallel to the axis (Fig. 4). That is, the position where the falling object is parallel to the x-axis or the position ( X _cg = x _cg ) where the rotation about the y-axis is φ _y = 0 is found. At this time, record the absolute length ( l ⁰ _xL , l ⁰ _xR ) of the left / right connecting line divided by the bar. The center of gravity of the found x-axis can be calculated using a "Pythagoras definition" that defines the length relationship of the right triangle, or can be determined using a tool such as a laser pointer (FIG. 5).

[Equation 1]

(Where X _cg = x _{cg and} Y _cg = y _cg )

Mark the identified center of gravity on the surface of the falling object and draw a horizontal line through X _cg to the surface of the falling object. Next, find the center of gravity for the y-axis, Y _cg . Attach the y-axis connecting line to the drop parallel to the y-axis passing through X _cg . The method described above is repeated to record the lengths of the Y _cg and the left / right connecting line ( l ⁰ _yL , l ⁰ _yR ) (FIG. 6).

&Quot; (3) "

l _x = l ⁰ _xL + l ⁰ _xR

l _y = l ⁰ _yL + l ⁰ _yR

Here, the following subscript convention is indicated. The number in the upper subscript is the degree of rotation of the falling object with respect to the reference axis, and the lower subscript represents the left (Left, L) and right (Right, R) of the center of gravity axes.

For reference, it is preferable for the convenience of the experiment that the length of the connecting line is slightly adjusted so that the height ( l _z ) of the two triangles under the line passing through the center of gravity is the same as mentioned above.

The center of gravity of the identified falling object and the center point of the connecting line holding the falling object must always coincide. This may prevent free rotation from occurring due to the rotation of the inertia of the falling object during free fall.

If the initial center of gravity is known, the free fall condition (0 deg, 0 deg) is the drop condition.

Next, as shown in Figure 6 after finding the center of gravity on the two plane axes after measuring the length of the connecting line l ⁰ _yL , l ⁰ _yR , l ⁰ _xL and l ⁰ _xR are recorded respectively. This step is to set the free fall angle.

Next, as shown in FIG. 7, 8, after measuring the connecting line length l ^{θ '} _xL , l ^θ' _xR , l ^θ _yL , l ^θ _yR for the arbitrary angle to be tested , it is recorded. This step is to set the free fall angle.

The fall angle is a quantified value, which is a convenient control value for the tester, and a quantitative angle measuring device is necessary to reflect this. The actual test is set in the angle measuring device, or posture setting device, and the set angle value is replaced by the length of the connecting line for reproducibility of the test.

Since the center of gravity of the falling object is identified and the test is repeated by setting various falling postures, the falling posture is expressed as the rotation angle ( φ _x , φ _y ) with respect to the reference plane axis. In order to set the quantified rotation angle, the attitude setting device in which the rotation angle is displayed is used (FIG. 7).

The posture setting device is manufactured to be similar to the principle of the 'adjustable reading stand' except that the anglemeter is installed on the rotating shaft so that the angle can be known.

After setting the desired angle, place the drop on the posture setting device. Position the vertices of the connecting line attached to the end of the center of gravity line on the vertical line of the center of gravity marked on the _drop , and then sequentially the lengths of the left and right connecting lines ( l ^{θ '} _xL , l ^θ' _xR ) and ( l ^θ _yL , l ^θ _yR ) is recorded (FIG. 8). The table below shows examples of various test conditions.

φ _x
(deg) φ _y
(deg) x-axis connector length y-axis connector length Left (L) Right side (R) Left (L) Right side (R) Drop condition 1 0 0 l ⁰ _xL l ⁰ _xR l ⁰ _yL l ⁰ _yR Drop condition 2 30 30 l ³⁰ _xL l ³⁰ _xR l ³⁰ _yL l ⁶⁰ _yR Drop condition 3 60 45 l ⁶⁰ _xL l ⁶⁰ _xR l ⁴⁵ _yL l ⁴⁵ _yR

Since the length of the connecting line was measured by the falling posture angle adjusting device, a separate guide rail is not necessary.

If the falling object is light and has a large area like paper or feathers, the rotational force will be caused by air resistance. However, in general, in the case of home appliances such as mobile phones and laptops, the rotational force due to air resistance is considered to have a shape and weight that can be ignored. Could be. Therefore, rotational inertia does not occur if the center of gravity of the falling object and the center point of the falling mechanism coincide.

Next, after the falling object is mounted on the falling object fixing support using the extension line length determined as shown in FIG. 1, the falling object is dropped using the falling object detachment apparatus.

Next, as shown in FIG. 1, the behavior of the falling object impacting the floor is recorded using the falling behavior video recording apparatus. Examples of video shooting of the first and second impact behaviors are shown in FIGS. 10 and 11.

Next, as shown in FIG. 1, the acceleration magnitude, the impact amount, and the impact behavior of the falling object obtained from the falling object are stored and analyzed using the data collection device. An example of the amount of impact on the primary and secondary impact behavior is shown in FIG.

1 is a block diagram of a free-fall impact test apparatus according to the present invention.

Figure 2 shows the center of gravity and rotational inertia.

Figure 3 shows the coordinate system of the drop test and the falling posture setting parameters.

4 shows finding the center of gravity using a circular bar.

Figure 5 shows the coordinate system for the falling object and the length of the connecting line for the coordinate system and direction.

Figure 6 shows the center of gravity for the length and width direction of the falling object.

7 is a configuration diagram of a posture setting device for setting a falling object at an arbitrary angle.

Figure 8 shows the center of gravity for the length and width direction of the falling object having an arbitrary angle.

9 is a configuration diagram of a base plate on which an impact amount sensor is mounted and which includes a variable drop impact plate.

10 is a photograph showing the first drop impact behavior in the free fall of the mobile phone.

11 is a photograph showing the secondary impact behavior by the rebound after the first drop impact in the free fall of the mobile phone.

12 is a graph of the results obtained after the drop test.

13 is a flowchart illustrating a method for measuring a drop impact test according to a preferred embodiment of the present invention.

[Description of Symbols for Main Parts of Drawing]

1: base plate

2: pillar for dropping device support and height adjustment

3: fixed support

4: connecting line

5: Desorption device

6: acceleration sensor

7: impact sensor

8: Falling object video recording device

9: data collector

11: base plate

12: column height adjusting column

13: auxiliary substrate

14: angle adjuster and indicator

15: Guide for moving the connecting line left and right

16: angle holder

21: frame

22: variable drop shock plate

23: Shock plate separation prevention device

24: impact sensor

25: Impact sensor fixed groove

Claims (10)

delete delete delete delete delete delete delete A base plate placed on the floor and collided with a falling object; A pillar fixed to the base plate and installed in a vertical upper portion; Falling object fixing support is installed in the horizontal direction to the height adjustable on the top of the column, fixing the falling object; A falling object connecting line connecting the falling object fixing support and the falling object; A falling object detachment apparatus for detaching and falling the falling object from the falling object fixing support; A falling object acceleration sensor attached to the falling object and measuring the acceleration of the falling object; An impact amount sensor mounted on the bottom surface of the substrate to measure an impact amount of the falling object; A falling behavior video recording apparatus for photographing falling behavior of falling falling objects; A data collecting device connected to a falling object acceleration sensor, an impact amount sensor, and a falling motion video photographing device to collect and analyze measured data; And It includes a posture setting device for setting the falling posture of the falling object to the desired angle, The posture setting device A base plate located below; A height of the connection line installed on the base plate so as to move left and right, and connecting the connection line so that the height can be adjusted; An auxiliary base plate hinged to one side of the base plate to move at an angle with the base plate to accommodate falling objects; An angle adjuster and an indicator installed at a coupling portion of the base plate and the auxiliary base plate to adjust the angle of the auxiliary base plate and display the angle; A guide for moving the left and right connecting lines installed at the coupling portion of the base plate and the pillar to move the pillar from side to side; And The free drop impact test apparatus, which is provided at a joining portion of the base plate and the auxiliary base plate, and has an angle holder for fixing the auxiliary base plate and maintaining the angle after the auxiliary base plate is at a predetermined angle. A base plate placed on the floor and collided with a falling object; A pillar fixed to the base plate and installed in a vertical upper portion; Falling object fixing support is installed in the horizontal direction to the height adjustable on the top of the column, fixing the falling object; A falling object connecting line connecting the falling object fixing support and the falling object; A falling object detachment apparatus for detaching and falling the falling object from the falling object fixing support; A falling object acceleration sensor attached to the falling object and measuring the acceleration of the falling object; An impact amount sensor mounted on the bottom surface of the substrate to measure an impact amount of the falling object; A falling behavior video recording apparatus for photographing falling behavior of falling falling objects; And It includes a data collector for collecting and analyzing the measurement data in connection with the falling object acceleration sensor, impact amount sensor and falling motion video recording device, The substrate is A box-shaped frame having an upper portion and having a plurality of grooves for receiving an impact amount sensor in the lower portion; A variable drop impact plate which is detachably seated on an upper portion of the frame, and which has a falling surface colliding with a falling object in various forms; And Free fall impact test apparatus characterized in that it is provided in the upper portion of the frame horizontally inwardly provided with a shock plate departure preventing device for preventing the separation of the impact plate. 9. The free fall impact test apparatus according to claim 8, wherein the falling object detachment apparatus is electric, pneumatic, electromagnet or spring type.

Images