JP5896678B2 - Vibration isolation table - Google Patents

Description

  The present invention relates to a passive vibration isolation table that suppresses the transmission of vibration between a weighing / measurement device that requires measures against vibration and a base, a floor, and the like that are support bodies thereof.

  With the improvement of measurement technology, the measurement accuracy of measuring and measuring equipment has been dramatically improved. In recent years, an analytical electronic balance with a measurement value reading accuracy (minimum display) of 0.1 mg or less, and an ultra-high-precision micro electronic balance with 1 μg (0.001 mg) or less, weighing errors due to disturbances in the installation environment Has a great influence on the measured value. In particular, the effects of vibrations have been confirmed to be caused by earthquakes, shaking of buildings due to wind pressure due to low pressure and typhoon passing, and ground shaking due to passing heavy vehicles. In order to ensure the measurement accuracy of a weighing / measurement device, the measurement accuracy of the device itself is hindered unless vibration transmitted to the device is removed.

  Therefore, a vibration isolation table is used as a passive vibration countermeasure in order to suppress the transmission of vibration between the weighing / measuring device as the supported body and the base, floor, etc. as the support. . This type of anti-vibration table is generally composed of a platen with rigidity and weight equivalent to a stone table to be used as a balance installation table, and damper units (vibration isolation mechanisms) arranged at the four corners of the bottom of the platen. , Is composed of. In the damper unit, a gel material or the like is used as an element of a viscous term that attenuates vibration, a metal spring or the like is used as an element of an elastic term that supports weight, and rubber or viscoelasticity is used as an element that serves as both a viscous term and an elastic term. A diaphragm made of plastic or the like is used, and the conventional vibration isolation table has a damper unit (Patent Document 1) in which a plurality of vibration isolating rubbers are integrated and a viscoelastic resin between leaf spring materials. There is a damper unit (Patent Document 2) in which a plurality of laminated ones are stacked and these are fixedly integrated with each other.

Japanese Utility Model Publication No. 64-41738 (Figure 1, page 1, left column, right column) JP2007-255690 (FIG. 3, paragraph 0020)

  However, the characteristics required for the vibration isolation table are different for various measuring and measuring devices. For example, a general-purpose balance requires several kilograms, while the analytical balance requires several grams, and the general-purpose balance body has a mass of about 4 kg, whereas the analytical balance has a mass of about 4 kg. Is about 10 kg. If these are placed on the same vibration isolation table, in general-purpose balances, an error will occur in the measurement value due to the inclination of the surface plate due to the large amount of the balance, so a vibration isolation table that stably supports with a large spring constant is desired. On the other hand, in the analytical balance, since the measured value becomes unstable due to insufficient performance of the vibration isolator, a vibration isolator having a relatively large viscosity term with a small spring constant is desired.

  On the other hand, in the conventional vibration isolation table described above, in any of Patent Documents 1 and 2, the element responsible for the viscoelastic term that determines the vibration isolation performance is configured as an inseparably integrated damper unit. It is only possible to obtain the specified vibration isolation performance corresponding to the diaphragm used in the system, and it is not possible to freely design the optimal viscoelastic term for weighing and measuring equipment that has different vibration isolation characteristics requirements. It was. In other words, there has been a problem in that various types of measuring / measuring devices are not configured to provide optimum vibration isolation performance. Therefore, if the user owns multiple weighing / measurement devices, the burden of having to prepare multiple vibration isolation tables suitable for each device is to use the optimal vibration isolation device for each device. was there.

  According to the present invention, various measuring / measuring devices that require countermeasures against vibration can be provided with optimal vibration isolation characteristics for each device, and viscoelasticity terms can be obtained by using one or more diaphragms. It is intended to provide a general-purpose vibration isolation table that improves the degree of design freedom and allows the user to freely change the setting at the same time.

In order to achieve the above object, the anti-vibration table according to claim 1, intervening been metering and measurement equipment between the support metering and measuring device and the metering and measuring equipment is supported member a platen which is placed, in the anti-vibration table having a, a vibration damping mechanism having viscoelasticity for the lower support of the surface plate, the vibration damping mechanism, the entire Ri viscoelastic member der shaped dished comprising a diaphragm, said diaphragm, with respect to a fixed portion extending downward from said surface plate, with an opening orientations are possible plurality stacked mountable de direction for supporting the platen vertically upwards, mounting and the state, the diaphragm outer periphery fixing unit, and wherein the portion other than the diaphragm outer peripheral portion is a movable portion, the space defined between the bottom surface of the plate by the diaphragm movable part is sealed To do.

  (Function) Because the diaphragm made of viscoelastic material can be stacked in the direction (vertical direction) to support the surface plate vertically, and each diaphragm can be separated and added freely. By changing the number of diaphragms used from one to a plurality, it becomes possible to freely change the viscoelasticity of the vibration isolation mechanism by combining (stacking) the diaphragms.

  According to a second aspect of the present invention, in the vibration isolator according to the first aspect, the diaphragm includes a metallic ring at a central axis and an outer peripheral part thereof, and viscoelasticity is provided between the central axial ring and the outer peripheral ring. The diaphragms are connected to each other, and the overall shape of the diaphragm is configured in a dish shape. The rigidity obtained by combining the diaphragms functions in parallel with the platen support direction.

  (Operation) The diaphragm of the present application has an overall dish shape, and the outer peripheral portion and the central portion are formed of metal and the viscoelastic material between them. When the diaphragms are combined (when the diaphragms are stacked in the same direction), the viscoelasticity term The rigidity obtained by the portion having the is parallel to the surface plate support direction. That is, the diaphragms of the present application can be stacked and arranged so that the structure of the vibration isolation mechanism is in series with the support direction of the surface plate, and the rigidity of the vibration isolation mechanism is parallel with the support direction of the surface plate. It is configured so that it can be attached and detached from the vibration isolation mechanism.

According to a third aspect of the present invention, in the vibration isolation table according to the second aspect, a concave portion recessed in the surface plate is provided at a position above the vibration isolation mechanism on the bottom surface of the surface plate, and the diaphragm outer peripheral portion includes: The lamination bolt screw portion is provided with an insertion hole through which a plurality of lamination bolt screw portions extending downward from the outer peripheral edge portion of the concave portion of the bottom of the surface plate, which is the fixed portion, can be inserted, and in the direction of opening the diaphragm upward When the diaphragm center shaft is fixed with a center fixing bolt and the diaphragm is mounted, the outer peripheral part of the diaphragm becomes a fixed part, and the part other than the outer peripheral part of the diaphragm becomes a movable part. The space defined by the diaphragm movable part is sealed.

  According to a fourth aspect of the present invention, in the vibration isolation table according to any one of the first to third aspects, each viscoelastic value of the diaphragm is different for each diaphragm.

According to a fifth aspect of the present invention, in the vibration isolation table according to the third aspect , a cushioning material is disposed in the recess on the bottom surface of the surface plate.

  As described above, according to the first aspect of the invention, the elastic term (spring constant) and viscosity term (damper coefficient) of the vibration isolation mechanism can be freely changed in proportion to the increase or decrease of the number of diaphragms used. Therefore, the degree of freedom in designing the viscoelastic term of the vibration isolation mechanism is improved, and an optimal vibration isolation characteristic can be designed for each of various measurement / measurement devices that require vibration countermeasures. Further, since the viscoelastic term of the vibration isolation table can be adjusted simply by increasing or decreasing the number of diaphragms, the vibration isolation performance can be freely designed at the manufacturing stage or at the user level.

According to the invention according to claim 2, since the rigidity obtained when the diaphragms are combined (laminated) is designed to be parallel, the elastic term is compared with the design where the obtained rigidity is in series. It can be designed to a large size, and can support the weight of each weighing / measuring instrument to be supported and a wide range of weighing capacity, and can improve the vibration isolation performance. In addition, all the diaphragms laminated in the surface plate support direction have substantially the same mounting shape to the fixing member on the side of the face, that is, change the number of single parts used or combine diaphragms of different materials Since the vibration isolation performance can be designed only by using this method, it is possible to share parts and improve productivity in the manufacturing stage.

  According to the invention of claim 3, the bolt screw portion is protruded downward from the outer peripheral edge portion of the recess formed on the bottom surface of the platen, and the bolt screw portion is inserted into the insertion hole of the outer peripheral portion of the diaphragm to engage the two. When the bolt screw part is fastened with a nut or the like, a plurality of diaphragms can be fixed (attached) in a state where they are stacked in the vertical direction. When it is desired to separate the diaphragm, the diaphragm is removed from the bolt screw portion, and when it is desired to add the diaphragm to the vibration isolation mechanism, the diaphragm may be fitted into the bolt screw portion. That is, since the diaphragm can be easily attached to and detached from the vibration isolation mechanism, the vibration isolation performance can be changed easily at the manufacturing stage or at the user level. In addition, the plate-shaped diaphragms are stacked and the outer periphery of the diaphragm is designed to be a fixed part (hereinafter referred to as the outer peripheral fixing mechanism). The surface comes into contact with each other, and the space (air layer) defined by the concave portion on the bottom surface of the platen and the movable diaphragm portion is in a sealed state. Therefore, when there is a transmission vibration, the space is compressed and the space functions as an air damper, so that the vibration isolation performance is further improved.

  According to the invention which concerns on Claim 4, various types, such as a thing with a big spring constant and a big damper coefficient, are prepared for a diaphragm, and they are combined and laminated | stacked, The vibration isolation of a vibration isolation stand is carried out. The performance can be further finely adjusted.

  According to the fifth aspect of the present invention, if a mass heavier than the design value is placed on the vibration isolation table (overload), the bottom surface of the surface plate and the vibration isolation mechanism come into contact with each other and the vibration isolation mechanism is damaged. However, the position where there is a possibility of contact with the vibration isolation mechanism on the bottom surface of the surface plate is that a hollow is provided in one stage and the cushioning material serves as a stopper, so that the surface plate is above a certain level. Since it is regulated not to sink, the vibration isolation mechanism is not affected. Therefore, the shock absorbing material acts on an unexpected load, and damage to the vibration isolation mechanism and the measurement / measurement device can be prevented.

The front view which shows the use condition of the vibration isolator which concerns on this invention Longitudinal cross-sectional enlarged view when the vibration isolator is set for a general-purpose balance (cross-sectional view along line II-II shown in FIG. 1) Plan view of the diaphragm, the main part of the vibration isolation table Front view of the diaphragm Longitudinal sectional view of the diaphragm (sectional view taken along line VV shown in FIG. 3) Longitudinal cross section when the vibration isolator is set for an analytical balance

  1 to 6 show the best mode of the present invention, FIG. 1 is a front view showing a use state of the vibration isolation table according to the present invention, and FIG. 2 is a general scale for setting the vibration isolation table. FIG. 3 is a plan view of a diaphragm which is a main part of the vibration isolation table, FIG. 4 is a front view of the diaphragm, and FIG. FIG. 6 is a longitudinal sectional view when the diaphragm is set for an analytical balance. FIG. 6 is a longitudinal sectional view of the diaphragm (cross sectional view taken along line VV shown in FIG. 3).

  In these drawings, reference numeral 1 denotes a vibration isolation table according to the present embodiment, which is arranged at the four corners of a surface plate 10 made of a monolith of 370 mm wide, 455 mm long, and 8.5 mm thick, and a bottom surface 10a of the surface plate 10. The damper unit (vibration isolation mechanism) 20 is configured. A measuring / measuring device 3 is placed on the surface plate 10, and the vibration isolation table 1 is interposed between the measuring / measuring device 3 that is a support and a support 2 such as a floor or a desk.

  The four corners of the bottom surface 10a of the surface plate 10 are provided with a container portion 14 that is recessed in a columnar shape for the purpose of suppressing the overall height of the vibration isolation table and so that the damper unit 20 is surrounded by the surface plate 10 to some extent. In the central portion of the lower portion of the accommodating portion 14, a concave portion (a surface plate bottom surface concave portion 16) that is recessed in a columnar shape in the surface plate 10 is provided in the same circular shape as the accommodating portion 14. A cushioning material 60 made of an impact absorbing material is bonded and fixed to the bottom surface of the surface plate bottom surface recess 16 in the surface plate bottom surface recess 16 that is further recessed from the housing portion 14 in one step. The buffer material 60 is not limited to the above materials, and may be made of rubber or elastic plastic as long as it has a certain level of buffering property.

  Regarding the damper unit 20 which is a vibration isolation mechanism, first, members constituting the damper unit 20 will be described. The damper unit 20 mainly includes a base plate 30, a diaphragm 40, and a damper foot 50.

  The base plate 30 has a metal ring 31 having a diameter substantially the same as an outer diameter of a diaphragm 40 described later, provided with bolt holes 32 at three equally spaced intervals in the circumferential direction, and a low head screw 33 is inserted into the bolt hole 32 above the base plate 30. The head of the low-head screw 33 is fixed to the upper surface of the metal ring 31. Then, by fixing the upper surface of the base plate 30 to the outer peripheral edge portion (the bottom surface of the accommodating portion 14) of the bottom plate bottom surface recess 16 with an adhesive 80, the bolt screw portion 33a of the low head screw 33 is lowered from the base plate 30. Protruding. That is, the three laminated bolt screw portions 33a protrude downward from the outer peripheral edge portion of the surface plate bottom surface concave portion 16.

  The diaphragm 40 is a rubber diaphragm formed by connecting a metal central shaft ring 41 and an outer peripheral ring 42 with a rubber portion 43 having a predetermined hardness. In detail, as shown in FIGS. 3 to 5, the diaphragm 40 is formed by connecting the outer periphery of the center shaft ring 41 and the inner periphery of the outer peripheral ring 42 with a rubber portion 43 having a uniform thickness, and the outer peripheral ring 42. When the rubber portion 43 is molded, the central shaft ring 41 and the outer peripheral ring 42 are inserted into the rubber portion 43 so that the upper surface and the lower surface are covered with the rubber portion 43 to have a uniform thickness and are formed in a substantially truncated cone shape when viewed from the front. It is formed by molding.

  In other words, the diaphragm 40 includes a metal ring (a central shaft ring 41 and an outer peripheral ring 42) on the central shaft 40c and the outer peripheral portion 40d, and the diaphragm central shaft 40c has a circular hole by the central shaft ring 41. The outer peripheral part 40d has a horizontal flange part by the outer peripheral part ring 42, and the shape of the rubber part 43 connecting between them is bent in an eight-letter shape, and the entire outer shape of the outer peripheral part 40d extends in the horizontal direction. It is a viscoelastic member formed in the shape of a circular thin dish. As an example, the central shaft ring 41 is a metallic ring having an outer diameter of 12 mm, an inner diameter of 8.5 mm, a thickness of 5 mm, the outer ring 42 is a metallic ring having an outer diameter of 60 mm, an inner diameter of 40 mm, and a thickness of 3 mm, and the rubber portion 43 has a hardness of about 70 degrees. The ethylene-propylene-diene rubber is used, the portion connecting the outer periphery of the central shaft ring 41 and the inner periphery of the outer ring 42 is uniformly 5 mm thick, and the portion sandwiching the upper and lower surfaces of the outer ring 42 is uniformly 1 mm thick. did.

  When the static pressure is applied to the diaphragm 40, the overall basic shape maintains the plate shape as described above and supports the surface plate 10. However, when the measuring / measuring device 3 is loaded, When vibration such as shaking of the building due to wind pressure due to low pressure or typhoon passage, or shaking of the ground due to passing heavy vehicles occurs, the rubber part 43 expands and contracts by receiving a shear load, and the weight is increased. It functions as an elastic term to support and a viscosity term to damp vibrations, and attenuates and attenuates transmitted vibrations.

  Further, at three positions at equal intervals in the circumferential direction of the diaphragm outer peripheral portion 40d, there are provided insertion holes 40a through which the lamination bolt screw portions 33a extending from the base plate 30 fixed to the outer peripheral edge portion of the surface plate bottom surface concave portion 16 can be inserted. .

  The damper foot 50 is a metal support member having a flange shape in which the copper portion 50a is opened downward and the peripheral edge of the opening extends in the horizontal direction to form a flange portion 50b. The rubber feet 51 are bonded to four places (four corners) at regular intervals in the circumferential direction. The copper part 50a is provided with a central insertion hole 52 through which the center fixing bolt 21 described later can be inserted at the center part, and at the three circumferentially equally spaced positions of the copper part 50a, the above-described lamination bolt screw part. The long hole 53 is provided so that 33a may not contact the upper surface of the copper part 50a.

  Next, as shown in FIG. 2, the vibration isolation performance of the vibration isolation table 1 is as follows. The weighing / measuring device 3 has a body mass of about 4 kg, a weighing capacity of 3000 g, and a measurement value reading accuracy (minimum display) of 0.01 g. A configuration in which the damper unit 20 is set for a general-purpose balance on the assumption that a general-purpose balance is placed will be described. In the damper unit 20, three of the above-described diaphragms 40 are stacked in a direction to open upward in the direction in which the surface plate 10 is vertically supported. Specifically, the diaphragm 40 is inserted into the circular hole (center shaft ring 41) of the diaphragm center shaft 40c from the opening side through the center fixing bolt 21, and the diaphragm 40 is locked at the center while the diaphragm 40 is locked to the diaphragm outer peripheral portion 40d. The lamination bolt screw portion 33a is inserted into the provided insertion hole 40a, and the diaphragm 40 is also locked in the circumferential direction. After this is performed for the number of diaphragms 40 to be laminated, the lamination bolt screw portion 33a is fastened with the nut 70, and the center fixing bolt 21 is also fastened with the nut 70 via the copper portion 50a of the damper foot 50. Then, three diaphragms 40 having the same shape are laminated on the base plate 30 (lamination bolt screw portion 33a), and the diaphragm outer peripheral portion 40d is mounted as a fixed portion, and the portions other than the diaphragm outer peripheral portion 40d are mounted as movable portions. Thus, the damper unit 20 is configured. In addition, since all the diaphragms 40 are laminated in the same direction, the rigidity of the damper unit 20 is designed to function in parallel with the surface plate support direction. Further, when the diaphragm 40 is mounted, the outer peripheral edge portion (surface) of the surface plate bottom surface recess 16 and the diaphragm outer peripheral portion 40 d (surface) are in contact with each other via the base plate 30. At this time, the space between the outer peripheral surface of the bottom plate bottom surface recess 16 and the upper surface of the base plate 30 is airtight due to the presence of the adhesive 80, and the rubber portion 43 is pressed between the lower surface of the base plate 30 and the surface of the diaphragm outer peripheral portion 40 d. Since the diaphragm center shaft 40c is sealed with the center fixing bolt 21, the sealed space (air layer) S is defined by the bottom plate recess 16 and the movable portion (rubber portion 43) of the diaphragm 40. Is defined.

  The damper unit 20 for a general-purpose balance maintains the basic dish-shaped shape of each diaphragm 40 at the time of static pressure, that is, when only the mass load of the vibration isolation table 1 and the weighing / measurement device 3 is applied. The surface plate 10 is supported with the thickness of the diaphragm 40 being three heights high, but there is a load on the measuring / measuring device 3 or there is a transmission vibration from the support 2. In this case, by receiving a shear load, the basic shape of each diaphragm 40 is deformed, and the rubber portion 43 expands and contracts to a shape that eliminates bending (to a flat shape), and an elastic term peculiar to each diaphragm 40 (spring Constant) and a viscosity term (damper coefficient), and as a whole, functions as a damper unit 20 that dampens and attenuates vibration with viscoelastic terms corresponding to three diaphragms 40. At this time, since the damper unit 20 is designed so that the rigidity obtained by combining (laminating) the diaphragms 40 is in parallel, the elastic term (spring constant) is compared to the design in which the obtained rigidity is in series. It is possible to finely adjust the elastic term and viscosity term by using a different diaphragm, and at the same time, the overall height of the assembled diaphragm can be kept low. Furthermore, the space S is compressed, and the space S functions as an air damper.

  Next, as shown in FIG. 6, the vibration isolation performance of the vibration isolation table 1 is about 10 kg for the main body, the weighing capacity is 22 g, and the reading accuracy (minimum display) is 0.001 mg. A configuration in which the damper unit 20 is set for an analytical balance on the assumption that a microbalance will be placed will be described. For the microbalance, one diaphragm 40 described above is arranged in the support direction of the surface plate 10. This setting can be easily changed from the setting for the general-purpose balance described above. More specifically, the nut 70 of the center fixing bolt 21 that fixes the three diaphragms 40 at the center is removed in the reverse order to the above, the damper foot 50 is removed from the damper unit 20, and the nut of the laminated bolt screw portion 33a. 70 is removed, and two diaphragms 40 are extracted from the lamination bolt screw portion 33a. With one diaphragm 40 remaining, the nut 70 of the lamination bolt screw portion 33a is tightened again, and the copper foot 50a of the damper foot 50 is interposed. The center fixing bolt 21 is fastened with a nut 70. As a result, the damper unit 20 for the analytical balance maintains the plate shape as the basic shape of the diaphragm 40 in a state where only the mass load of the vibration isolation table 1 and the weighing / measuring device 3 is applied. The surface plate 10 is supported in a state where the plate 10 is lifted by a height corresponding to the thickness of the diaphragm 40. However, when there is a load on the measuring / measuring device 3 or when there is a transmission vibration from the support 2 The basic shape of the diaphragm 40 is deformed, and the vibration is vibration-damped and attenuated by a viscoelastic term for one diaphragm 40.

  According to the vibration isolation table 1 of the present embodiment, the diaphragm 40 having the same shape is arranged in series as the structure of the vibration isolation mechanism in the direction of supporting the surface plate 10 (vertical direction), and parallel as the rigidity of the vibration isolation mechanism. The number of diaphragms 40 can be arranged in layers from one to the other, and the diaphragms 40 can be freely separated and added to the damper unit 20 one by one. The viscoelasticity of the damper unit 20 can be freely changed simply by increasing or decreasing it.

  In contrast to the anti-vibration table 1 of the present embodiment, in the conventional anti-vibration table, the element responsible for the viscoelastic term that determines the anti-vibration performance is configured as an inseparably integrated damper unit. Because it is only possible to obtain the specified vibration isolation performance (constant viscoelasticity term) corresponding to the above, and it has not been configured to give optimum vibration isolation performance to various measuring and measuring devices. The user cannot freely design the optimal viscoelasticity term for the measuring and measuring equipment with different vibration isolation characteristics requirements. We had to prepare multiple vibration isolation tables suitable for each device.

  In contrast, in the present embodiment, the number of diaphragms 40 used can be increased or decreased. Therefore, the elastic term (spring constant) and viscosity of the damper unit 20 are proportional to the number of diaphragms 40 used. The term (damper coefficient) can be changed freely. For this reason, the degree of freedom in designing the viscoelastic term of the vibration isolation table 1 is high, and it is possible to design the optimal vibration isolation characteristics for each of various measuring and measuring devices that require countermeasures against vibration.

  That is, when a general-purpose balance is placed as the weighing / measuring device 3, the vibration isolator 1 is provided with a diaphragm 40 in order to prevent an error in the measurement value due to the inclination of the surface plate 10 due to the large amount of the balance. Use a plurality of anti-vibration tables that are stably supported with a large spring constant. On the other hand, when an analytical balance is placed as the weighing / measuring instrument 3, the vibration isolation table 1 is equipped with a general purpose to prevent the measurement value from becoming unstable due to insufficient performance of the vibration isolation table. It is possible to freely design the vibration isolator with a relatively large viscosity term with a small spring constant by reducing the diaphragm 40 as compared with the setting for the balance.

  Furthermore, the design change of the above-described vibration isolation characteristics can be achieved by separating the diaphragm 40 from the damper unit 20 by removing the unnecessary diaphragm 40 from the laminated bolt screw portion 33a extending downward from the surface plate bottom surface 10a. When it is desired to add 40 to the damper unit 20, it is only necessary to fit the diaphragm 40 to the bolt bolt portion 33a for lamination. That is, since the diaphragm 40 can be easily attached to and detached from the damper unit 20, the design of the vibration isolation performance (adjustment work of the viscoelastic term) can be easily performed.

  Therefore, for various measuring and measuring devices 3 that require countermeasures against vibration, the design flexibility of the viscoelastic term is improved, and at the same time, the setting can be freely changed at the manufacturing stage and at the user level. The anti-vibration table 1 that has been provided can be provided.

  In addition, the laminated diaphragms 40 have the same shape, that is, the vibration isolation performance can be designed simply by changing the number of single parts used. Also improves.

  In general, if the vibration isolation table uses rubber for the diaphragm of the vibration isolation mechanism, it is necessary to repair the vibration isolation mechanism due to deterioration of the rubber part. Since the rubber diaphragm 40 can be easily attached and detached as described above, the diaphragm can be easily replaced even at the user level, and maintenance is easy.

  Further, it is assumed that the weighing / measuring device 3 is loaded with a mass heavier than the specified capacity (overload is applied). If the base plate bottom surface recess 16 and the buffer material 60 are not provided on the vibration isolation table 1, the diaphragm 40 becomes flat when the overload is applied, the surface plate 10 sinks, and the diaphragm center shaft 40c The head of the protruding central fixing bolt 21 and the bottom of the housing portion 14 may come into contact with each other and the damper unit 20 may be damaged. However, in the vibration isolator 1 of this embodiment, the head of the central fixing bolt 21 The upper position of the damper unit 20, which is a position where there is a possibility of contact with the platen, is a hollow portion due to a bottom plate bottom surface recess 16 that is further recessed in one step from the bottom of the housing portion 14. Since the provided cushioning material 60 functions as a stopper, the platen 10 is regulated not to sink more than a certain level, and even if an overload is applied, the damper unit 20 and thus the measuring / measuring device 3 is broken. It is prevented.

  In the above-described embodiment, the hardness of the rubber portion 43 of the diaphragm 40 is set to about 70 degrees, and one or more diaphragms 40 having the same viscoelasticity are laminated. However, each viscoelasticity of the diaphragm 40 is laminated. The value may be different for each diaphragm 40. That is, for example, a diaphragm 401 having a relatively large elastic term (spring constant) having a hardness of about 90 degrees or a diaphragm 402 having a relatively large viscosity term (damper coefficient) having a hardness of about 50 degrees is prepared. When the vibration isolator 1 is set for a general-purpose balance having a weight of about 5200 g, the diaphragm 401 is laminated or the diaphragm 401 is mixed with the diaphragm 40 and laminated so that the spring constant becomes larger. When designing vibration performance or setting the vibration isolation table 1 as a measuring and measuring device 3 for a tuning fork viscometer, the tuning fork viscometer is equivalent to the capacity of the measuring container (about 40 ml (about 40 g at the maximum). Therefore, the diaphragm 402 is used or the diaphragm 402 so that the damper coefficient becomes relatively large. And the like to vibration isolation performance design laminated mix the diaphragm 40, the vibration isolation performance of the anti-vibration table 1 can be further fine-tuning. Further, by making the surfaces of the diaphragms 40, 401, and 402 corrugated (by making them undulate), the viscosity term (damper coefficient) can be further improved. Can be prepared.

  Note that the dish-shaped diaphragm 40 may be laminated in the direction of opening downward. That is, one stacking bolt screw portion 33a extends downward from the recess 16 on the bottom surface of the platen and is fixed by being inserted through the diaphragm central shaft 40c, and the diaphragm central shaft 40c is designed as a fixed portion and the others as movable portions. As for the vibration mechanism (inner periphery fixing mechanism), the vibration isolation performance obtained by the diaphragm 40 (and the combination thereof) is equivalent to the outer periphery fixing mechanism of the above embodiment although the air damper effect cannot be expected.

DESCRIPTION OF SYMBOLS 1 Anti-vibration stand 2 Support body 3 Weighing / measurement apparatus 10 Surface plate 10a Surface plate bottom surface 16 Surface plate bottom surface recessed part 20 Damper unit 33a which is a vibration isolation mechanism Lamination bolt screw part 40 Diaphragm 40a Diaphragm insertion hole 40c Diaphragm center axis 40d Diaphragm outer periphery Part 41 Center shaft ring 42 Outer ring 43 Rubber part 60 Buffer material S Sealed space

Claims (5)

Has a surface plate interposed the metering and measurement equipment between the support metering and measuring device and the metering and measuring equipment is the supported body is placed, a viscoelastic to lower support said plate A vibration isolation table having a vibration isolation mechanism,
The vibration damping mechanism comprises the entire Ri viscoelastic member der shape a dished diaphragm, the diaphragm, with respect to a fixed portion extending downward from said surface plate, vertical said plate in a direction to open upward together in the direction of the support can be detachably stacking a plurality mounted to, in the state of mounting the diaphragm outer periphery fixing unit, a portion other than the diaphragm outer peripheral portion is a movable portion, a bottom surface of said plate A vibration isolation table characterized in that the space defined by the diaphragm movable part is in a sealed state.   The diaphragm is provided with a metallic ring at the central axis and the outer peripheral part, and the central axial ring and the outer peripheral ring are connected by a material having viscoelasticity, and the entire diaphragm shape is configured in a dish shape. 2. The vibration isolation table according to claim 1, wherein the rigidity obtained by the combination of the diaphragms functions in parallel with the surface plate support direction. A recessed portion that is recessed in the surface plate is provided at a position above the vibration isolation mechanism on the bottom surface of the surface plate, and the diaphragm outer periphery is below the outer peripheral edge portion of the surface plate bottom surface recessed portion that is the fixed portion. An insertion hole is provided through which a plurality of bolts for stacking bolts can be inserted. When the diaphragm is mounted, the outer peripheral portion of the diaphragm becomes a fixed portion, the portion other than the outer peripheral portion of the diaphragm becomes a movable portion, and the space defined by the concave portion on the bottom surface of the platen and the movable portion of the diaphragm is sealed. The vibration isolation table according to claim 2.   4. The vibration isolation table according to claim 1, wherein viscoelastic values of the diaphragms are different for each diaphragm. 5. The vibration isolation table according to claim 3, wherein a cushioning material is disposed in the concave portion of the surface plate bottom surface.

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