JP6213694B2 - Projection material - Google Patents

Description

  The present disclosure relates to an iron-based projection material used for performing blasting of a casting by blasting.

  Conventionally, a blasting process in which hard particles are projected onto a casting has been performed on the casting in order to perform polishing to remove scale such as casting sand adhered to the surface after casting or rust formed on the surface of the base material. It was. Such polishing of castings is often performed using spherical steel particles (see, for example, Patent Document 1). Moreover, the projection material which adjusted particle diameter distribution is also known (for example, refer patent document 2).

JP-A-6-297132 JP 2001-353661 A

  In the casting before sand removal, a cast sand layer that is a relatively thick brittle material is formed in the outermost layer, and a scale layer, a scale, and a base material mixed layer are formed in the lower layer. In order to remove these efficiently, it is necessary to use a projection material having a large scouring force and high scouring efficiency. However, the projection material used for blasting is generally used for other purposes such as deburring and improving surface roughness. For this reason, although the particle diameter and hardness of a projection material can be suitably selected according to a use, the projection material in which particle diameter distribution etc. were adjusted specifically for the blasting of a casting is not found. In addition, there is a projection material with a particle size distribution adjusted, such as the projection material described in Patent Document 2, but it has a larger blasting force suitable for blasting of castings, and the blasting efficiency. There is a demand for high projection materials.

  In the operation of the blasting apparatus, when a predetermined amount of the projecting material is put into the blasting apparatus and the casting is cleaned, the projecting material repeats the cycle of projection, recovery, fine powder removal, and projection. When the projection is repeated, the projection material is crushed into fine powder. Such fine powder is sorted and removed by a separator. Since the amount of the projection material in the blasting apparatus is reduced by the amount removed, the projection material corresponding to the decrease is replenished. When the projection material is repeatedly supplied, pulverized, and discharged outside the apparatus, the particle size distribution of the projection material in the apparatus is stabilized at a constant particle size distribution different from the initial particle size distribution. This state of stable particle size distribution is called operating mix. In order to efficiently polish the casting, it is necessary to manage the particle size distribution of the projection material in the apparatus after forming the operating mix so as to be suitable for the polishing.

  In this technical field, in the iron-based projection material used for performing blasting of castings, a projection material suitable for blasting of castings in which both the blasting force and the blasting efficiency are improved is provided. It is hoped that. Moreover, it is desired to provide a projection material in which the particle size distribution of the projection material in the apparatus after forming the operating mix is suitable for the polishing of the casting.

  In order to achieve the above object, a projection material according to one aspect of the present invention is an iron-based projection material used for polishing the surface of a casting by blasting, and the projection material has a Vickers hardness (Nippon Kogyo). The standard JIS Z 2244) is in the range of HV300 to 600, the particle diameter d of the projection material is 0.85 mm <d ≦ 2.36 mm, and the distribution of the particle diameter d of the projection material is a frequency distribution (Japan) The frequency of the particle diameter section 1.18 mm <d ≦ 1.40 mm in the industrial standard JIS G 5904) is maximized, and the frequency of the particle diameter section 1.70 mm <d ≦ 2.00 mm is corresponding to the frequency. The frequency is 0.4 to 1.0 times, and the frequency of the particle diameter interval 1.40 mm <d ≦ 1.70 mm is 0.2 to 0.7 times. Hereinafter, symbols with JIS are Japanese Industrial Standards.

  According to this projection material, in the polishing of the casting, the polishing force is improved by particles having a particle diameter section of 1.70 mm <d ≦ 2.00 mm, and by particles having a particle diameter section of 1.18 mm <d ≦ 1.40 mm. The coverage (actual dent area of the projection material per fixed area) can be improved. Thereby, this blasting material can be made into a blasting material suitable for scouring of a casting in which both the scouring force and the scouring efficiency are improved. Here, “particles having a particle diameter section of 1.18 mm <d ≦ 1.40 mm” pass through a standard sieve having a nominal aperture of 1.40 mm in JIS Z8801 (2006) and having a nominal aperture of 1.18 mm. Particles captured (non-passing) with a standard sieve are shown. Further, the projection material may include a maximum of about 5% of small-diameter particles that are equal to or smaller than the lower limit value of the particle diameter section.

  The distribution of the particle diameter d of the projection material is such that the frequency of the particle diameter section 1.70 mm <d ≦ 2.00 mm with respect to the frequency of the particle diameter section 1.18 mm <d ≦ 1.40 mm in the frequency distribution (JIS G 5904). Is 0.6 to 0.8 times, and the frequency of the particle diameter section 1.40 mm <d ≦ 1.70 mm may be 0.3 to 0.6 times. The blasting material thus configured can further improve the scouring force and scouring efficiency, and can be suitably used.

  The projection material has a particle diameter d of 1.18 mm <d ≦ 2.36 mm and a particle diameter section of 1.70 mm <d ≦ 2.00 mm, and the first projection material having a maximum frequency, and a particle diameter d of 0.1. It may be a mixture with the second projection material that has a maximum frequency of 85 mm <d ≦ 1.40 mm and a particle diameter section of 1.18 mm <d ≦ 1.40 mm. As described above, the projection material can be produced by mixing the first projection material adjusted so as to improve the sharpening force and the second projection material adjusted so as to improve the coverage. .

  The projection material has a first particle body having a particle size distribution exceeding 1.18 mm and a particle size of 1.18 mm or less after the operating mix is formed, which is stabilized with a constant particle size distribution by operation of the blasting apparatus. When divided into second particles exceeding 0.85 mm and third particles having a particle diameter of 0.85 mm or less, (the ratio of the first particles) ≧ (the ratio of the second particles) ≧ (the first The ratio of the three particles may be satisfied. In this case, the projection material is suitable for the polishing of the casting in which the particle size distribution of the projection material in the apparatus after forming the operating mix is larger than that of the conventional projection material in which the first particles having a large polishing force are larger than the conventional projection material. Distribution.

  The ratio of the first particles may be 60% by weight or more, the ratio of the second particles may be 5 to 30% by weight, and the ratio of the third particles may be 20% by weight or less. By making the particle size distribution of the projection material in the device after the operating mix is formed into the above particle size distribution, both the blasting force and the blasting efficiency are improved, and the blasting material is suitable for blasting of castings. Can do.

  According to various aspects of the present invention, in an iron-based projection material used for blasting a casting by blasting, it is suitable for blasting a casting with improved blasting power and blasting efficiency. Projection material can be provided. In addition, according to various aspects of the present invention, it is possible to provide a projection material in which the particle size distribution of the in-device projection material after the formation of the operating mix is a distribution suitable for polishing of a casting.

It is a schematic diagram of the particle diameter distribution of the projection material which concerns on embodiment. It is explanatory drawing which shows the particle diameter distribution of the projection material of an Example. It is explanatory drawing which shows the surface state of the sample after a blast test. It is a table | surface explaining the surface state shown in FIG. It is explanatory drawing which shows the measurement result of the rust removal degree of the sample after a blast test. It is explanatory drawing which shows the result of a life test. It is explanatory drawing which shows the particle size distribution (estimation) after operation mix formation.

  The projection material according to the present embodiment is an iron-based projection material that can be used for polishing the surface of a casting by blasting.

  The projection material is a spherical shot made of an iron-based material selected from the range of Vickers hardness HV300-600. Here, as such an iron-based material, for example, C: 0.8 to 1.2% by weight, Mn: 0.35 to 1.20% by weight, Si: 0.40 to 1.50% by weight, P ≦ 0.05 wt%, S ≦ 0.05 wt%, a component system containing the balance Fe and inevitable impurities, and having a tempered martensite structure or a similar structure can be employed. Such particles can be prepared by a known method such as a water atomizing method. Here, the projection material has sufficient hardness for the object to be cleaned at HV300 or more, and the projection material has sufficient toughness at HV600 or less. Thus, since the projection material which concerns on this embodiment has sufficient hardness and toughness, it can be used suitably for the polishing of the casting surface. Here, the Vickers hardness HV is based on Japanese Industrial Standard JIS Z 2244 (2009).

  FIG. 1 is a schematic diagram of a particle size distribution of a projection material according to an embodiment. The particle diameter on the horizontal axis shows the lower limit value of the particle diameter section as a representative value. The same applies to the following particle size distribution diagrams. The particle diameter d of the projection material is 0.85 mm <d ≦ 2.36 mm, and the distribution of the particle diameter d of the projection material is a particle diameter section 1.18 mm <d ≦ 1.40 mm in the frequency distribution (JIS G 5904). The frequency of the particle diameter section 1.70 mm <d ≦ 2.00 mm is 0.4 to 1.0 times the frequency, and the particle diameter section 1.40 mm <d ≦ 1. It adjusts so that the frequency of 70 mm may be 0.2 to 0.7 times. Here, the measuring method of particle size distribution is based on Japanese Industrial Standard JIS G 5904 (1966), and is shown by weight distribution.

  The distribution of the particle diameter d of the projection material is such that, for example, the frequency of the particle diameter section 1.70 mm <d ≦ 1.40 mm, and the frequency of the particle diameter section 1.70 mm <d ≦ 2.00 mm is 0.6-0. And the frequency of the particle diameter section 1.40 mm <d ≦ 1.70 mm is adjusted to be 0.3 to 0.6 times. According to this, the scouring force and the scouring efficiency can be further improved, and it can be suitably used for scouring a casting.

  The projection material having such a particle size distribution is a first projection material in which the particle diameter d is 1.18 mm <d ≦ 2.36 mm and the frequency of the particle diameter section 1.70 mm <d ≦ 2.00 mm is maximized. And a second projection material in which the particle diameter d is 0.85 mm <d ≦ 1.40 mm and the frequency of the particle diameter section 1.18 mm <d ≦ 1.40 mm is maximized. it can. That is, the projection material is a mixture of the first projection material and the second projection material.

  For example, if only the first projection material is used for polishing a casting, the polishing force can be increased. However, since the number of particles per unit weight decreases, the coverage (actual dent of the projection material per fixed area) Area). On the other hand, the second projection material can improve the coverage, but has a low blasting force against a particularly strong sand scale as compared with the first projection material. Therefore, although it has a sufficient blasting force for removing the foundry sand and scale, the scouring force is insufficient to remove seizure and the like generated on the surface of the foundry sand, and the blasting time becomes longer.

  In the projection material according to the present embodiment, by mixing these projection materials so as to have the particle size distribution described above, it is possible to maintain the respective advantages and supplement the portion where the scouring ability is insufficient. The sharpening force can be improved by the first projecting material, and the coverage can be improved by the second projecting material. That is, it is possible to perform the cleaning with both the cleaning force and the cleaning efficiency improved.

  Moreover, by producing the projection material by mixing the first projection material and the second projection material, the particle size distribution can be made substantially continuous. Thereby, since the size of the dent by the blast has a continuous distribution, the coverage can be increased and the blast can be efficiently performed.

  The first projecting material and the second projecting material are classified by using a sieve having a mesh size of 0.85 to 2.36 mm as defined in JIS Z 8801 (2006), by using a known method such as a water atomizing method. It can be prepared by mixing and adjusting to obtain a desired particle size distribution.

  Next, a method for polishing a casting by blasting using the above-mentioned projection material will be described.

  In order to perform the polishing of the casting using the projection material according to the present embodiment, for example, a known centrifugal blasting apparatus as described in Patent Document 1 can be used. Note that the polishing method is not limited to the method using the blasting apparatus.

  The blast device includes a hopper that stores and supplies a fixed amount of the projection material, an impeller unit that projects the projection material, a circulation device that circulates the projection material, a separator that separates the projection material from sand and scale, and a dust collector. .

  The projecting material is thrown into the impeller unit from the hopper, and the projecting material thrown into the impeller unit is accelerated in the impeller unit and projected onto the casting placed in the projection chamber. Thereby, the casting is polished.

  The projected blast material is collected by the circulation device together with the sand and scale removed from the casting by the blasting process, and sent to the separator.

  In the separator, the projection material is dropped into an apron, and sand, scales and pulverized fine projection material are selected by the air flow generated by the dust collector, and they are discharged out of the dust collector and the apparatus. The projection material effective for the cleaning is supplied again to the impeller unit and recycled.

  Since the amount of projection material in the apparatus decreases by the amount discharged to the outside of the apparatus, it is necessary to replenish the amount of projection material corresponding to the decrease amount. The decrease in the blast material is detected by the load current value of the impeller unit, and a new blast material is automatically or manually supplied to the hopper.

  As a result of a series of operations in which the above-mentioned projection, fine powder discharge from the apparatus, and replenishment are repeated, the particle size distribution of the in-device projection material is stabilized at a constant particle size distribution different from the particle size distribution of unused projection material. This state of stable particle size distribution is called operating mix. It is important that the projection material is managed so that the particle size distribution of the projection material in the apparatus after forming the operating mix can be efficiently polished.

  By using the projection material according to the present embodiment, the particle size distribution in the blasting apparatus after forming the operating mix is (the ratio of the first particles) ≧ (the ratio of the second particles) without using a special device or method. ) ≧ (ratio of the third particles) can be obtained as a characteristic distribution. That is, it can be realized in the normal operation of the blasting apparatus. The projection material is classified into a first particle having a particle diameter of 1.18 mm, a second particle having a particle diameter of 1.18 mm or less and exceeding 0.85 mm, and a third particle having a particle diameter of 0.85 mm or less. doing. Even if the particle size distribution is controlled so that the ratio of the first particles is 60% by weight or more, the ratio of the second particles is 5 to 30% by weight, and the ratio of the third particles is 20% by weight or less. Good.

  This particle size distribution was compared with the particle size distribution according to “ECONOMICAL AND FUNCTIONAL ASPECTS OF BLAST CLEANING ABRASIVES BLASTING THEORY” (published by WHEEL ABRATOR, 1972), which was conventionally used as a guideline for the operating mix in polishing of castings. The comparison results are shown in Table 1. The “third particle” in the present embodiment is a mixture obtained by mixing the third and fourth particles of the conventional pointer in Table 1.

As shown in Table 1, the projection material according to the present embodiment includes a much larger amount of the first granule having a large scouring force than the conventional projection material due to the addition of the first projection material. A characteristic distribution is shown.

  The first particles have a high scouring force and are particularly effective for removing a strong scale layer on the outermost layer of the casting. The polishing time can be shortened by increasing the number of first particles compared to the conventional projection material.

  The amount of the second granule is the same as that of the conventional one, and thereby coverage can be ensured.

  The third granule has a low scouring force and cannot effectively remove the scale, so it was reduced compared to the conventional projection material. Moreover, since the 3rd particle | grain contains casting sand and mixing of casting sand can be suppressed by reducing a 3rd particle body, it can suppress the wear of the components which comprise a blast apparatus. .

  When the projection material according to the present embodiment is used, the particle size distribution in the blasting apparatus after forming the operating mix can be set to the above-described distribution suitable for the polishing of the casting.

(Example of change)
The form of the projection material is not limited to shots, and grit, cut wires, and the like can also be used.

  The first projecting material and the second projecting material may be made of the same material, or may be formed of materials having different hardness.

(Effect of embodiment)
According to the projection material according to the present embodiment, when blasting of a casting is performed by blasting, it is possible to provide a projection material suitable for blasting of a casting in which both the blasting force and the blasting efficiency are improved. . Moreover, it can be set as the projection material from which the particle distribution of the projection material in an apparatus after operating mix formation becomes distribution suitable for the polishing of a casting.

  Examples performed to confirm the effects of the present invention will be described below.

(1) Cleaning test A cleaning test using the projection material according to the embodiment was performed. The work piece used in this test was made of FC250, poured at a pouring temperature of 1350 ° C., thawed 30 minutes after pouring, and cooled at a cooling rate of 3 ° C./min. . The product weight is about 3.5 kg. The projection test apparatus used for the test was a shot blast SNTX-I type (Shinto Kogyo Co., Ltd.), and the projection speed was 73 m / s and the table rotation speed was 6 rpm.

  The projection material to be used for the test is a first projection material adjusted so that the particle diameter d is 1.18 mm <d ≦ 2.36 mm and the frequency of the particle diameter section 1.70 mm <d ≦ 2.00 mm is maximized. And a second projection material adjusted so that the frequency of particle diameter d is 0.85 mm <d ≦ 1.40 mm and particle diameter interval 1.18 mm <d ≦ 1.40 mm is maximized, Were prepared by adjusting the particle size distribution. In either case, the hardness is HV450. FIG. 2 shows the particle size distribution. FIG. 2 is an explanatory diagram showing the particle size distribution of the projection material of the example.

This particle size distribution satisfied the conditions for the particle size distribution of the projection material according to the embodiment. As a comparative example, a test with a steel shot having a diameter of 1.7 mm (particle diameter range: 1.40 mm <d ≦ 2.36 mm) was also performed. The projection density was 150 to 300 kg / m ² . In both the examples and comparative examples, the projection material was put into a projection test apparatus, and after performing continuous operation and replenishment to form an operating mix, a projection test was performed.

The sample surface after the erosion test is shown in FIG. FIG. 3 is an explanatory view showing the surface state of the sample after the blast test. The convex and concave portions and character portions (engraved portions) were enlarged to observe the finished state, and visual evaluation was performed. Details of visual appearance are summarized in FIG. FIG. 4 is a table for explaining the surface state shown in FIG. As shown in FIGS. 3 and 4, in the comparative example, the projection density in a range of ^{150kg / m 2 ~250kg / m 2} , that the scale is present in the dotted line region surrounded by a dotted line was confirmed. The scale was removed at a projection density of 300 kg / m ² . For this reason, in the comparative example, a projection density of 300 kg / m ² was required to finish. Meanwhile, in the embodiment, a projection density in a range of ^{150kg / m 2 ~200kg / m 2} , that the scale is present in the dotted line region surrounded by a dotted line was confirmed. The scale was removed at a projection density of 250 kg / m ² . In other words, it was confirmed that the working example was finished at a projection density of 250 kg / m ² .

  The flat area was enlarged and observed, and the degree of rust removal was measured. The results are shown in FIG. FIG. 5 is an explanatory view showing the measurement result of the degree of rust removal of the sample after the polishing test. As the projection density increased, the degree of rust removal increased. A degree of rust removal of 90% or more corresponds to the finished point of visual appearance evaluation. In the example, it was confirmed that an equivalent finish could be realized in a state where the projection density was 17% lower than that of the comparative example, and the polishing time could be shortened.

(2) Life test The life test of the projection material was carried out under the conditions of a projection speed of 60 m / s and a cut screen of 0.710 mm using an Irvine type life tester in accordance with SAE J445 in accordance with the regulations of 100% Replacement Method. The results are shown in FIG.
FIG. 6 is an explanatory diagram showing the results of a life test. The number of cycles to reach the cumulative replenishment amount of 100 g of the new projection material was 3400 cycles in the example, compared with 2940 cycles in the comparative example, and a 16% improvement in life was recognized.

  The life test simulates the operation of an actual blasting device, and the particle size distribution after forming the operating mix can be estimated from the state of the projection material after the test. The results are shown in FIG. FIG. 7 is an explanatory diagram showing a particle size distribution (estimation) after the operation mix is formed. This particle size distribution satisfies the particle size distribution after forming the operating mix of the projection material according to the embodiment, and it is confirmed that a desired particle size distribution can be obtained in the blasting process using the projection material according to the embodiment. It was done.

Claims (5)

An iron-based projection material used for blasting the surface of a casting by blasting,
The projection material has a Vickers hardness in the range of HV300 to 600,
The particle diameter d of the projection material is 0.85 mm <d ≦ 2.36 mm,
Regarding the distribution of the particle diameter d of the projection material, the frequency of the particle diameter section 1.18 mm <d ≦ 1.40 mm in the frequency distribution is maximized, and the particle diameter section 1.70 mm <d ≦ 2.00 mm with respect to the frequency. The frequency of 0.4 to 1.0 times, and the frequency of the particle diameter section 1.40 mm <d ≦ 1.70 mm is 0.2 to 0.7 times.
Projection material.   The particle diameter d of the projection material is distributed such that the frequency of the particle diameter section 1.70 mm <d ≦ 2.00 mm is 0.6 with respect to the frequency of the particle diameter section 1.18 mm <d ≦ 1.40 mm in the frequency distribution. The projection material according to claim 1, which has a particle diameter interval of 1.40 mm <d ≦ 1.70 mm and a frequency of 0.3 to 0.6 times.   A first projection material in which the particle diameter d is 1.18 mm <d ≦ 2.36 mm and the frequency of the particle diameter section 1.70 mm <d ≦ 2.00 mm is maximized; and the particle diameter d is 0.85 mm <d ≦ The projection material according to claim 1 or 2, wherein the projection material is a mixture with a second projection material that has a maximum frequency of 1.40 mm and a particle diameter section of 1.18 mm <d ≦ 1.40 mm. The particle size distribution of the projection material after the formation of the operating mix that is stabilized with a constant particle size distribution by operation of the blasting device is the first particle body having a particle size of 1.18 mm and a particle size of 1.18 mm or less of 0.85 mm. When divided into a second granular body exceeding and a third granular body having a particle diameter of 0.85 mm or less,
(Ratio of first particles) ≧ (ratio of second particles) ≧ (ratio of third particles)
The projection material as described in any one of Claims 1-3 which satisfy | fills.   5. The projection material according to claim 4, wherein the ratio of the first particles is 60% by weight or more, the ratio of the second particles is 5 to 30% by weight, and the ratio of the third particles is 20% by weight or less.