JP2018005267A - Derivation method for cushioning material characteristic, cushioning material characteristic derivation program, and cushioning material characteristic derivation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a derivation method for cushioning material characteristics that can obtain relation between maximum acceleration and static stress while greatly reducing the trouble to conduct an impact load test.SOLUTION: A derivation method for cushioning material characteristics comprises: a step S1 of deriving relation between first energy E needed to deform a cushioning material and strain based upon relation between dynamic stress σ and the strain of the cushioning material; a step S2 of deriving strain such that second energy ε absorbed per unit volume of the cushioning material and the first energy E become equal to each other; a step S3 of deriving dynamic stress σ of the cushioning material corresponding to the value of the strain derived in the step S2; a step S4 of deriving maximum acceleration X applied to a packaged object based upon the value of the dynamic stress σ derived in the step S3; a step S5 of deriving static stress σ; and a step S6 of deriving relation between maximum acceleration X and static stress σ.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a buffer material characteristic deriving method, a buffer material characteristic deriving program, and a buffer material characteristic deriving device used for designing a buffer material for an object to be packed.

  Conventionally, when packing a product (a product to be packed), a cushioning material is used to protect the product so that the product is not damaged during transportation. For example, as disclosed in Non-Patent Document 1, the appropriate thickness and amount of use of the cushioning material may be set using a maximum acceleration-static stress diagram, and a strain-static stress diagram may also be used. Used as needed.

  An apparatus for designing a shock absorbing material using the shock absorbing material characteristics is disclosed in Patent Document 1, for example.

JP 2004-240580 A

Transport packaging basics and practice, Koshobo, Inc., September 25, 2008, pages 120-123

  However, if the maximum acceleration-static stress diagram and strain-static stress diagram have not been published by the shock absorber manufacturer, the designer should use the maximum acceleration-static stress diagram and, if necessary, strain- Although a static stress diagram is to be obtained, there is a problem that a very large number of impact load tests are required for this purpose.

  For example, when a maximum acceleration-static stress diagram is prepared according to JIS Z 0235: 2002 (packaging buffer material-evaluation test method), three test pieces, five test conditions or more, and one test condition for the same test condition If the number of times (or 5 times) is set as one set, the falling height of the weight is 8 ways, and the thickness of the buffer material is 10 ways, for example, 3 × 5 × 1 (or 5) × 8 × 10 = 1200 ( Or 6000), and it is necessary to perform at least 1200 impact load tests.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain the relationship between the maximum acceleration and the static stress while greatly reducing the labor for performing the impact load test. A buffer material characteristic deriving method, a buffer material characteristic deriving program, and a buffer material characteristic deriving device are provided.

  In order to achieve the above object, the buffer material characteristic derivation method according to the first configuration of the present invention is based on the relationship between the dynamic stress and strain of the buffer material and is required to deform the buffer material. A first step for deriving a relationship between energy and strain, and a strain in which the second energy and the first energy absorbed per unit volume of the cushioning material are equal when the packaged item is dropped from a predetermined height. The second step derived from the relationship between the first energy and the strain, and the third step derived from the relationship between the dynamic stress and the strain, the dynamic stress of the buffer material corresponding to the strain value derived in the second step. A step, a fourth step for deriving a maximum acceleration applied to the package when the package is dropped from a predetermined height based on the value of the dynamic stress derived in the third step, and a package Cushioning material when placed on cushioning material The relationship between the maximum acceleration and the static stress is derived based on the fifth step for deriving the generated static stress, the value of the maximum acceleration derived in the fourth step and the value of the static stress derived in the fifth step. And a sixth step.

  According to the first configuration of the present invention, by performing the first to sixth steps, the relationship between the maximum acceleration and the static stress is derived based on the relationship between the dynamic stress and the strain of the buffer material. be able to. The relationship between the dynamic stress and strain of the cushioning material can be obtained by performing impact load tests several times (for example, 1 to 3 times), so that the maximum acceleration and A relationship with static stress can be obtained.

It is the block diagram which showed the structure of the buffer material characteristic derivation | leading-out apparatus of one Embodiment of this invention. It is a flowchart for demonstrating the process sequence of buffer material characteristic derivation | leading-out using the buffer material characteristic derivation apparatus of one Embodiment of this invention. It is the figure which showed the dynamic stress-strain diagram obtained from an impact load test. It is the figure which showed the relationship of the 1st energy required in order to deform | transform a buffer material, dynamic stress, and distortion. It is the figure which showed the 1st energy-strain diagram which the 1st derivation | leading-out part of the buffer material characteristic derivation | leading-out apparatus of one Embodiment of this invention derived | led-out. It is the figure which showed the distortion from which 2nd energy and 1st energy become equal. It is the figure which showed the maximum acceleration-static stress diagram derived | led-out by the 6th derivation | leading-out part of the buffer material characteristic derivation | leading-out apparatus of one Embodiment of this invention. It is the figure which showed the strain-static stress diagram derived | led-out by the 7th derivation | leading-out part of the buffer material characteristic derivation | leading-out apparatus of one Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  As shown in FIG. 1, a buffer material characteristic deriving device (computer) 100 according to an embodiment of the present invention includes a drive unit 1, a storage unit 2, a control unit 3, an interface unit 4, a display unit 5, and an operation unit 6. , Each is electrically connected to each other.

  A program (such as a buffer material characteristic deriving program) that realizes processing in the buffer material characteristic deriving device 100 is provided by a recording medium 10 such as a CD-ROM. When the recording medium 10 on which the program is recorded is set in the drive unit 1, the program is installed from the recording medium 10 into the storage unit 2 via the drive unit 1. The program installation does not necessarily have to be provided by the recording medium 10, and may be downloaded from another computer via a network. The storage unit 2 stores the installed program and also stores necessary files and data.

  The control unit 3 includes a CPU and controls the entire cushioning material characteristic deriving device 100 and executes predetermined processing according to a program stored in the storage unit 2. Further, the control unit 3 reads data necessary for execution of processing from the storage unit 2 and stores the calculation (derivation) result in the storage unit 2. The interface unit 4 is used for connecting to a network. The display unit 5 includes a liquid crystal display panel or the like, and displays an input screen and a processing result executed by the control unit 3. The operation unit 6 includes a keyboard, a mouse, and the like, and various operation instructions are input by the user.

  Here, in the present embodiment, the control unit 3 includes the first derivation unit 3a, the second derivation unit 3b, the third derivation unit 3c, the fourth derivation unit 3d, the fifth derivation unit 3e, the sixth derivation unit 3f, and the 7 derivation unit 3g is included.

  The first deriving unit 3a derives the relationship between the first energy and strain necessary for deforming the buffer material based on the relationship between the dynamic stress and strain of the buffer material.

  The second deriving unit 3b first derives a strain in which the second energy and the first energy absorbed per unit volume of the cushioning material are equal when the product (packaged object) is dropped from a predetermined height. Derived from the relationship between the first energy and strain derived by the part 3a.

  The third deriving unit 3c derives the dynamic stress of the buffer material corresponding to the strain value derived by the second deriving unit 3b from the relationship between the dynamic stress and the strain of the buffer material.

  The fourth deriving unit 3d derives the maximum acceleration applied to the product when the product is dropped from a predetermined height based on the value of the dynamic stress derived by the third deriving unit 3c.

  The fifth derivation unit 3e derives a static stress generated in the cushioning material when the product is placed on the cushioning material.

  The sixth deriving unit 3f derives the relationship between the maximum acceleration and the static stress based on the value of the maximum acceleration derived by the fourth deriving unit 3d and the value of the static stress derived by the fifth deriving unit 3e. .

  The seventh deriving unit 3g derives the relationship between the strain and the static stress based on the strain value derived by the second deriving unit 3b and the static stress value derived by the fifth deriving unit 3e.

  Next, a processing flow for deducing buffer material characteristics using the buffer material characteristic deriving device 100 will be described with reference to FIG.

  First, as a preliminary preparation, a designer (or an operator) performs an impact load test to obtain a relationship between dynamic stress and strain of the buffer material. Specifically, for example, according to JIS Z 0235: 2002, the impact load test shown in FIG. 3 is performed by performing an impact load test only once for three test pieces, one test condition, and the same test condition. Stress σ-strain diagram (relation between dynamic stress and strain of buffer material) is obtained. At this time, a numerical data table (relation between dynamic stress σ and strain of the buffer material) corresponding to the dynamic stress σ-strain diagram of the buffer material is also obtained. As shown in FIG. 3, the dynamic stress σ-strain diagram obtained by the impact load test has a small variation in numerical values. Therefore, only one impact load test may be performed with one test piece. Good.

  Then, the obtained test result is input to the shock absorbing material characteristic deriving device 100 by the designer (user) using the operation unit 6, and the test result is stored in the storage unit 2. The buffer material property deriving device 100 may be input with a numerical value read from the dynamic stress σ-strain diagram or described in a numerical data table corresponding to the dynamic stress σ-strain diagram. A numerical value may be input. Further, the impact load testing device and the buffer material property deriving device 100 may be connected by a cable, and the test result may be automatically transmitted to the buffer material property deriving device 100.

  Next, when the buffer material characteristic deriving device 100 is instructed to the buffer material characteristic deriving device 100 via the operation unit 6 by the designer, in step S1 (first step) in FIG. Based on the relationship between the dynamic stress σ and the strain of the material, the relationship between the first energy E and the strain necessary to deform the buffer material is derived. Specifically, the first deriving unit 3a creates the dynamic stress σ-strain diagram shown in FIG. 3 based on the test result input by the user. And the 1st derivation | leading-out part 3a carries out the definite integration of the dynamic stress (sigma) -strain curve, as shown in FIG. Derived). At this time, a numerical data table (a relationship between the first energy E and the strain) corresponding to the first energy E-strain diagram is also obtained.

In step S2 (second step), the second deriving unit 3b is configured to absorb the second energy ε [MPa] and the first energy E [[] that are absorbed per unit volume of the cushioning material when the product is dropped from a predetermined height. [MPa] is equalized from the relationship between the first energy E and the strain. Specifically, the mass of the product is m [kg], the gravitational acceleration is 9.8 [m / s ² ], the drop height of the product is h [m], and the contact area between the cushioning material and the product is A [mm] ² ], where the thickness of the cushioning material in the product drop direction is t [mm], the second energy is ε [MPa] = m [kg] × 9.8 [m / s ² ] × h [m] / (A [mm ² ] × t [mm]). The second derivation unit 3b reads the strain corresponding to ε [MPa] as shown in FIG.

  In step S3 (third step), the third derivation unit 3c uses the dynamic stress σ [MPa] of the buffer material corresponding to the strain value derived by the second derivation unit 3b as shown in FIG. It is derived from a numerical data table corresponding to a σ-strain diagram or a dynamic stress σ-strain diagram.

In step S4 (fourth step), the fourth deriving unit 3d applies the product when the product is dropped from a predetermined height based on the value of the dynamic stress σ [MPa] derived by the third deriving unit 3c. The applied maximum acceleration X [m / s ² ] (where 1G = 9.8 [m / s ² ]) is derived. Specifically, since σ [MPa] = m [kg] × X [m / s ² ] / A [mm ² ], the maximum acceleration is X [m / s ² ] = σ [MPa] × A [ mm ² ] / m [kg].

In step S5 (fifth step), the fifth deriving unit 3e derives the static stress σ _s [MPa] generated in the buffer material when the product is placed on the buffer material. Specifically, as described in JIS Z 0235: 2002, the static stress is obtained by σ _s [MPa] = m [kg] × 9.8 [m / s ² ] / A [mm ² ].

In step S6 (sixth step), the sixth deriving unit 3f determines the value of the maximum acceleration X [m / s ² ] derived by the fourth deriving unit 3d and the static stress σ _s [derived by the fifth deriving unit 3e. Based on the value of [MPa], the relationship between the maximum acceleration X and the static stress σ _s is derived. Specifically, the sixth deriving unit 3f is configured so that, in each of the above formulas, the product mass m [kg], the product drop height h [m], the contact area A [mm ² ] between the cushioning material and the product, A specific numerical value is applied to each of the thickness t [mm] of the cushioning material, the product mass m [kg], the drop height h [m] of the product, and the contact area A [mm ² ] between the cushioning material and the product. By sequentially changing one or more of the buffer material thickness t [mm], the maximum acceleration X-static stress σ _s diagram (the relationship between the maximum acceleration X and the static stress σ _s ) shown in FIG. To derive. At this time, a numerical data table (relationship between the maximum acceleration X and the static stress σ _s ) corresponding to the maximum acceleration X-static stress σ _s diagram is also obtained. Note that the maximum acceleration X-static stress σ _s diagram shown in FIG. 7 is created by the number in which the drop height h [m] of the product is changed.

In step S7 (seventh step), the seventh deriving unit 3g is based on the value of the strain derived by the second deriving unit 3b and the value of the static stress σ _s [MPa] derived by the fifth deriving unit 3e. The relationship between strain and static stress σ _s is derived. Specifically, the seventh lead-out part 3g includes the mass m [kg] of the product, the drop height h [m] of the product, the contact area A [mm ² ] between the cushioning material and the product, and the thickness t [of the cushioning material. mm], a strain-static stress σ _s diagram shown in FIG. 8 based on a specific strain value and a static stress σ _s [MPa] value obtained by sequentially changing one or more of [mm]. (Relationship between strain and static stress σ _s ) is derived. At this time, a numerical data table (relationship between strain and static stress σ _s ) corresponding to the strain-static stress σ _s diagram is also obtained. Note that the strain-static stress σ _s diagram shown in FIG. 8 is created by the number in which the drop height h [m] of the product is changed.

Above manner, the maximum acceleration X- static stress sigma _s diagram was created, and strain - static stress sigma _s diagram is or are displayed on the display unit 5, a recording medium by operating the operation unit 6 by the user 10 or output to another computer via the interface unit 4. And according to the method disclosed by the nonpatent literature 1, for example, the designer sets the suitable thickness and usage-amount of a shock absorbing material using the obtained data.

In the present embodiment, as described above, the relationship between the maximum acceleration X and the static stress σ _s is derived based on the relationship between the dynamic stress σ and the strain of the buffer material by executing steps S1 to S6. can do. Since the relationship between the dynamic stress σ and the strain of the buffer material is obtained by performing the impact load test several times (for example, 1 to 3 times), the maximum acceleration is achieved while greatly reducing the labor for the impact load test. The relationship between X and static stress σ _s can be obtained.

Further, as described above, the method includes step S7 for deriving the relationship between the strain and the static stress σ _s based on the value of the strain derived in step S2 and the value of the static stress σ _s derived in step S5. . Thereby, the relationship between the strain and the static stress σ _s can also be derived.

  Further, as described above, in step S1, the relationship between the first energy E and the strain is derived by integrating the dynamic stress σ-strain curve. Thereby, the relationship between the first energy E and the strain can be easily derived based on the relationship between the dynamic stress σ and the strain.

Further, as described above, in step S6, the maximum acceleration is obtained by changing one or more of the mass m of the product, the drop height h of the product, the contact area A between the cushioning material and the product, and the thickness t of the cushioning material. The relationship between X and static stress σ _s is derived. Thereby, the relationship between the maximum acceleration X and the static stress σ _s can be easily derived.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  For example, in the above embodiment, the control unit 3 includes a CPU and the storage unit 2 is provided separately from the control unit 3. However, the control unit 3 may include a CPU and a storage unit.

3a 1st derivation part 3b 2nd derivation part 3c 3rd derivation part 3d 4th derivation part 3e 5th derivation part 3f 6th derivation part 3g 7th derivation part 100 shock absorbing material characteristic derivation device (computer)

Claims (6)

A first step of deriving a relationship between first energy and strain necessary for deforming the buffer material based on a relationship between dynamic stress and strain of the buffer material;
A strain in which the second energy absorbed per unit volume of the cushioning material and the first energy are equal when the packed object is dropped from a predetermined height is derived from the relationship between the first energy and the strain. A second step to
A third step of deriving the dynamic stress of the buffer material corresponding to the strain value derived in the second step from the relationship between the dynamic stress and strain;
Based on the value of the dynamic stress derived in the third step, a fourth step of deriving a maximum acceleration applied to the packaged object when the packaged item is dropped from the predetermined height;
A fifth step of deriving a static stress generated in the buffer material when the object to be packed is placed on the buffer material;
A sixth step of deriving a relationship between the maximum acceleration and the static stress based on the value of the maximum acceleration derived in the fourth step and the value of the static stress derived in the fifth step;
A method for deriving shock-absorbing material characteristics, comprising:   7. A seventh step of deriving a relationship between strain and static stress based on the strain value derived in the second step and the static stress value derived in the fifth step. Item 2. A method for deriving the shock absorbing material characteristics according to Item 1.   3. The buffer material property derivation method according to claim 1, wherein, in the first step, the relationship between the first energy and the strain is derived by definite integration of a dynamic stress-strain curve.   In the sixth step, the mass of the packaged object, the fall height of the packaged object, the contact area between the cushioning material and the packaged object, the thickness of the cushioning material in the falling direction of the packaged object, The buffer material property deriving method according to claim 1, wherein the relationship between the maximum acceleration and the static stress is derived by changing one or more.   A buffer material characteristic deriving program that causes a computer to execute the buffer material characteristic deriving method according to any one of claims 1 to 4. A first deriving unit for deriving a relationship between first energy and strain necessary for deforming the buffer material based on a relationship between dynamic stress and strain of the buffer material;
A strain in which the second energy absorbed per unit volume of the cushioning material and the first energy are equal when the packed object is dropped from a predetermined height is derived from the relationship between the first energy and the strain. A second derivation unit,
A third deriving unit for deriving the dynamic stress of the buffer material corresponding to the strain value derived by the second deriving unit from the relationship between the dynamic stress and strain;
A fourth deriving unit for deriving a maximum acceleration applied to the packed object when the packed object is dropped from the predetermined height based on the value of the dynamic stress derived by the third deriving unit;
A fifth deriving portion for deriving a static stress generated in the buffer material when the packaged object is placed on the buffer material;
A sixth deriving unit for deriving a relationship between the maximum acceleration and the static stress based on the value of the maximum acceleration derived by the fourth deriving unit and the value of the static stress derived by the fifth deriving unit;
A buffer material characteristic deriving device comprising:

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