Wet end sealing material for ball screw and ball screw using the same

Abstract

[Problem] To provide an end seal material for a ball screw that maintains high dust resistance and lubricity for a long period of time even in a poor environment where there is fine dust, such as paper powder of a few μm in size, that absorbs lubricant and reduces its lubricity, and that is easy to install and replace, has high maintainability, is simple to handle, and has a large adjustment range.In a ball screw in which an external screw shaft with a continuous arc-shaped groove and a nut part are screwed together via a large number of steel balls inserted between the external thread and the internal thread, and the nut is fed back and forth on the external screw shaft, the end seal material attached to the front or rear of the nut part has a support frame body arranged on the outer periphery of the external screw shaft, a base fabric part whose back surface is fixed to the inner circumferential surface of the support frame body, and cut pile protruding from the surface of the base fabric part towards the groove part, the tip parts of the cut pile bend to contact the groove part so as to seal the gap between the groove part and the support frame body, and a lubricant is previously held between the pile fibers of the cut pile.

Description

Technical Field

[0001] The present invention relates to a wet end sealing material for a ball screw and a ball screw using the same. A ball screw is one of the mechanical elements that converts rotational motion into linear motion. In order to improve the efficiency of the screw, a large number of steel balls are inserted between the male screw shaft with an arc-shaped groove and the nut part to change the sliding friction into rolling friction, which is a special feed screw. It is an excellent mechanism in that the conversion between rotational motion and linear motion is reversible, and a higher screw efficiency can be obtained compared with a general screw. The present invention relates to an end sealing member for sealing the gap between the arc-shaped groove of the screw shaft of this ball screw and the end of the nut member or the end of the retainer member.

[0002] The present invention relates to a wet sealing material and a ball screw using the same, in which a pile portion is attached to both ends of the nut portion or both ends of the retainer portion in a form that bites into the arc-shaped groove of the screw shaft, and when the nut or the retainer enclosing the nut rotates back and forth to drive the screw groove, foreign matter is prevented from entering the nut or the retainer, and furthermore, grease is used to maintain dust prevention and extend the service life. The ball screw of the present invention includes a retainer type.

Background Art

[0003] Now, in mechanical motion, there are linear motion and rotational motion, and positioning mechanisms are known for each. Compared with the case of rotational motion that is widely and practically used with bearings and the like using bearings, it has been extremely difficult and highly technical to put the rolling elements of linear motion into practical use. Of course, if rolling elements can be used for linear motion, the rolling friction coefficient will be small and the starting resistance will also be low, etc., and its usefulness is expected. However, if it is to be put into practical use, in the mechanism of linear motion, it is necessary to provide a mechanism that satisfies all of the requirements such as being highly rigid, being labor-saving, operating quickly and lightly, having high positioning accuracy and a long service life. Therefore, it has not been easy to satisfy the required accuracy in practical use. Therefore, even now, further improvements are desired to meet such requirements.

[0004] And, since the ball screw is a mechanical element that requires the nut (or a retainer including the nut) to move smoothly, stably, and accurately back and forth on the screw shaft for a long time, sufficient durability is required. For this purpose, lubricity and dustproofness are highly regarded. For example, if powder or foreign matter enters the inside of the nut or retainer, the fluidity of the balls in the groove will deteriorate, and the life of the ball screw will be greatly reduced. Also, an increase in friction may lead to malfunction. Since ball screws may be used in an environment where there is a large amount of dust such as powder and cutting foreign matter, troubles caused by dust and the like are likely to occur. As a result, it may also cause malfunction of the entire machine or equipment using the ball screw.

[0005] Therefore, in order to continue operating even in an environment where a large amount of powder or foreign matter exists, a mechanism has been proposed that covers the entire set screw with a bellows to prevent foreign matter from entering the device. However, if it is covered with a bellows, the surrounding of the mechanism will be largely covered, and it becomes difficult to say that the maintainability is good, such as the need to remove the bellows. Also, even if it is covered with a bellows, it is not easy to completely prevent the intrusion of powder or foreign matter. Therefore, the powder or foreign matter that has once entered the inside of the bellows will cause malfunctions in the operation, so it has been difficult to reduce the maintenance frequency.

[0006] Therefore, in order to avoid the situation where powder or foreign matter enters the inside of the slider part of the linear guide and causes malfunctions, a seal member composed of any one or a plurality of synthetic rubbers such as nitrile rubber, resins, metal scrapers, and brushes is arranged at the end of the slider or in the gap between the slider and the rolling elements, or a sealing material made of synthetic resin composed of an elastic body installed so as to abut against the plate between the inner plate and the outer plate of the chain is used (see, for example, Patent Document 1).

[0007] However, a slight gap is likely to occur between the seal member and the rolling surface of the slider. If an attempt is made to reduce the gap, the seal member must be precisely manufactured in a predetermined shape in advance, resulting in a high manufacturing cost for the seal member. Also, since the sealing material itself is made of a material such as solid rubber, it is likely to be chipped or deformed by foreign matter. Once chipping occurs, there is a concern that a large amount of foreign matter will flow in from the chipped part. In addition, it is not easy to precisely ensure the sealing performance. When trying to eliminate the gap by using a jig or the like to make the seal unit abut against the rail so as to play the role of a sealing material, problems such as an increase in additional torque and an increase in friction during reciprocating motion will occur. Moreover, in the case of a ball screw, the thread groove exists in an arc shape and the ball runs on it, so the shape is complex and it is not easy to seal.

[0008] In addition, in the current unit, the seal and lubrication are separate parts. In addition to the end seal, a mechanism is provided to continuously supply grease from a grease retention mechanism such as nonwoven fabric or fiber net, which increases the installation dimensions and causes loss in the driving range, which is also a factor in the size of the device. In addition, if the grease is absorbed into powder or foreign matter and becomes a mass, it can cause chipping or deformation of the sealing material, which can cause malfunction of the ball screw mechanism in situations where there is insufficient sealing performance.

[0009] Furthermore, repeated movement can cause deformation and wear of the seal material, which can then be scraped off and impair its sealing function, leading to malfunctions caused by the leakage of lubricant and the intrusion of powder and foreign matter into the slider. Therefore, frequent cleaning and replacement of the seal material and the grease used for lubrication have become virtually essential for stable operation, which has tended to increase maintenance costs.

[0010] Even if frequent cleaning and replacement of the seal members and lubricating grease are performed, when the thread groove of the ball screw becomes worn down by powder and foreign matter, the replaced seal member does not abut the thread groove sufficiently, and gaps tend to occur. If a large amount of powder or foreign matter gets mixed in the gap, the guide mechanism with the ball screw and the chain itself become unusable, and the device itself must be replaced.

[0011] The applicant has proposed a dry seal material using cut pile for the linear motion mechanism. The applicant has proposed a side seal unit for a linear motion mechanism in which the ground yarn part of the cut pile, which has a warp and weft double weave structure consisting of two layers, a surface layer of front warp and front weft, and a back layer of back warp and back weft, is fixed to the inner side of the base, and the tips of the pile fibers are raised from the ground yarn part of the cut pile toward the inner side, cut and raised, and the tips of the cut pile are arranged to abut against the cross-sectional shape of the shaft, and the seal material made of cut pile is arranged at the front and rear ends of the slider (see, for example, Patent Document 2). However, using only cut pile may not be sufficient to maintain the sealing property against powder and foreign matter for a long time. For example, in an environment containing fine powder such as paper powder that absorbs lubricant, the dry cut pile will slide, resulting in insufficient dustproof performance. Therefore, a higher sealing retention property has been desired. Furthermore, in a sealing mechanism with a complex shape such as a ball screw, an appropriate sealing material and structure have been desired.

Prior Art Documents

Patent Documents

[0012]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0013] Therefore, the problems to be solved by the present invention are to provide an end sealing material having high dustproof and lubricating properties in order to maintain a ball screw with high precision and long life in good condition. In particular, to provide an end sealing member capable of maintaining dustproof and lubricating properties for a long time even in a harsh environment with fine dust such as several μm of fine powder and fine dust such as several μm of paper powder that absorbs lubricant and deprives lubricity. And it is an end sealing member that can more easily hold the lubricant and supply and maintain it for a longer time. Also, to provide a ball screw equipped with an end sealing member having a simple and easy-to-handle structure that is easy to attach and replace and has high maintainability. That is, to provide a highly followable sealing material that can be easily attached without the need to precisely adjust the abutting state during assembly, and to provide a sealing material with high followability, large adjustment width, and easy adjustment for wear at sliding parts such as shafts and complex shapes, and a ball screw using such a sealing material. In the past, for maintenance such as removing and replacing the sealing material, in order to ensure smooth mobility of the nut part and the retainer part, adjustment work of the sealing setting with an appropriate clearance was necessary, and replacement by a skilled person was required. However, the present invention provides a sealing material with a large adjustment margin that can ensure shielding performance even with a rough attachment, enabling easier removal and replacement. And it is to provide a mechanism of a sealing material that enables easy attachment and replacement.

Means for Solving the Problem

[0014] The first means for solving the problems of the present invention is In a ball screw in which a male screw shaft having an arc-shaped continuous groove portion and a nut portion are screwed together via a large number of steel balls inserted between the male screw and the female screw, and the nut is sent back and forth on the male screw shaft, An end sealing material attached to the front or rear of the nut portion is A support frame body arranged on the outer periphery of the male screw shaft, A base cloth portion whose back surface is fixed to the inner peripheral surface of the support frame body, It has cut piles protruding from the surface of the base cloth portion toward the groove portion, The tip portions of the cut piles are bent so as to close the gap between the groove portion and the support frame body and contact the groove portion, There is a lubricant held in advance between the pile fibers of the cut piles An end sealing material made of wet cut piles, characterized in that.

[0015] The second means of the present invention is an end sealing material made of the cut piles described in the first means, characterized in that the cut piles are spirally arranged on the inner periphery of the support frame body so as to face the groove portion over a length of one rotation or more of the outer periphery of the male screw shaft. Desirably, the cut piles are spirally arranged on the inner periphery of the support frame body so as to face the groove portion over a length of two rotations or more of the outer periphery of the male screw shaft.

[0016] The third means of the present invention is that the lubricant held between the pile fibers of the cut pile is grease with a consistency number of No. 1 to No. 4 in JIS K2220, and it is the end seal material described in any one of the first or second means. That is, the mixing consistency range of the grease is 175 to 340. Further, the grease may also be held on the base fabric of the cut pile.

[0017] The fourth means of the present invention is the end seal material described in the third means, characterized in that the grease is any one of lithium grease, molybdenum compound-containing grease, and urea-based grease. Lithium grease is lithium soap-based grease, and molybdenum disulfide may be further added. Urea-based grease is, for example, diurea grease, triurea grease, or tetraurea grease.

[0018] The fifth means of the present invention is the end seal material described in any one of the first to fourth means, characterized in that the pile length of the cut pile is 2 mm or more. Since the tip of the pile can bend and bite into the gap between the inner circumference of the support frame and the groove, it is preferably a pile length of 2 mm or more as the length that can bend in the gap. More preferably, it is 3 mm or more.

[0019] The sixth means of the present invention is the end seal material described in any one of the first to fifth means, characterized in that the pile fibers of the cut pile are composed of crimped multifilament fibers. Also, the cross-section of each filament of the crimped pile fiber is preferably a non-round cross-section, and further a cross-section such as a star shape, * shape, or hollow cross-section, which has a larger surface area.

[0020] The seventh means of the present invention is the end seal material described in any one of the first to sixth means, characterized in that the cut pile is made of a woven fabric.

[0021] The eighth means of the present invention is an end seal material according to any one of the first to sixth means, characterized in that the cut pile is made of a knitted fabric.

[0022] The eighth means of the present invention is a ball screw provided with a male screw shaft, a nut portion, and steel balls, in which the end seal material described in any one of the first to seventh means is detachably fixed to the front and rear of the nut portion.

Advantages of the Invention

[0023] According to the above means for solving the problems of the present invention, the end seal material is in a state of holding a lubricant in advance, and the pile tips of the cut pile are in contact with the arc-shaped groove portion of the male screw shaft and are bent. That is, the pile tip portion is bent at the gap between the groove portion and the inner periphery of the support frame body and firmly bites in, so the adhesion is high, and while rotating spirally, the gap is firmly blocked, so it is possible to prevent foreign substances such as fine powder and dust from entering from between the groove portion. Furthermore, a lubricant such as grease is held between the pile fibers in advance, and the pile can hold these lubricants for a long time even after moving back and forth. Therefore, the pile tips that have bitten into the gap also slide smoothly due to the lubricant, so it is difficult for the movement to deteriorate due to friction, and the lubricant is held between the piles without disturbing the smooth movement of the nut portion, so the viscosity is increased with the shield effect, and a high dustproof effect can be obtained for a long time. That is, rather than supplying a lubricant for smooth driving, it is held between the piles and the base fabric as a moisturizing agent for maintaining the shielding property, so that the pile tips have an appropriate viscosity as if they were wet, so a high shielding property can be obtained for a long time.

[0024] And if the lubricant for maintaining the shield is grease with an appropriate consistency, a sufficient amount can be held in advance between the pile fibers, and even after repeating the back-and-forth movement while rotating, the grease can be maintained between the fibers for a long time. Therefore, as a pile with a viscous wet shield, the shielding property can be stably maintained for a long time.

[0025] Since the cut pile of the sealing material is arranged spirally around the male screw shaft facing the groove portion, a long contact distance with the cut pile is ensured when moving in the groove. Therefore, although it is not easy to shield a groove with a complex three-dimensional shape such as the arc-shaped groove portion of the male screw groove, since the cut pile moves while contacting the groove portion over a long distance, the shielding force can be easily increased. On the other hand, since it is wet with grease or the like, the cut pile that abuts in a bent manner does not extremely increase the frictional resistance, so it does not hinder the movement of the nut portion and smooth movement can be maintained.

[0026] Also, if the lubricant held between the piles is grease with an appropriate consistency, it can prevent fine powder and dust of several micrometers from entering for a long time. Furthermore, even for dust such as fine paper powder of several micrometers that absorbs oil into paper fibers, the grease is not overly absorbed by the paper fibers and can maintain a certain degree of moisturized state, and the state where the grease is held on the pile can be maintained. Therefore, the sealing performance and lubricity are not inhibited, and the nut portion (retainer portion) can operate smoothly for a long time.

[0027] Since the hair tips serving as shields bend and enter so as to bite into the gap with the groove portion, it is not only easy to prevent the intrusion of dust and the like, but also has little frictional resistance because it slides wet and does not hinder the movement of the nut portion. Therefore, there is no problem in closely adhering in a bent manner. Thus, when detaching, exchanging, or attaching the sealing material, clearance adjustment can be achieved by bending the sealing material without requiring strict clearance adjustment by a skilled person, so it is easy to ensure appropriate shielding performance. In particular, since the groove portion is recessed in an arc shape and has a length such that the pile legs bend, it can be sufficiently adhered. Despite the non-uniform groove depth, the pile can follow.

[0028] Therefore, when the sealing material needs to be periodically detached and replaced, it becomes possible to simply replace it without requiring skill by merely supplying the replacement parts of the sealing material to the customer site without dispatching a skilled worker, and it is possible to ensure stable shielding performance without adjustment. Since it is easy to attach and detach in this way, maintenance replacement can be appropriately carried out at the discretion of the on-site personnel, and the sealing performance can be exhibited even by replacement by relatively unskilled laypersons.

[0029] That is, the pile of the sealing material in contact is likely to come into contact with the groove portion relatively evenly due to the repulsive force when the pile fibers are bent. In addition, the tips of the pile are bent so as to bite into the gap, so in addition to being easily and evenly adhered by the repulsive force of the pile when the pile is mounted, even if some deviation occurs, the bitten pile closes the gap, so the sealing performance is hardly impaired. Furthermore, since a viscous wet lubricant is held around the pile, the sealing performance is more easily maintained. By intentionally biting in like this, it is easier to adjust compared to materials with high frictional resistance that require strict adjustment of contact such as rubber or felt, and it becomes smooth and has high dustproofness. Especially for coping with particularly complex spiral groove portions, cut pile is suitable because it can follow.

[0030] In addition, by holding a lubricant between the pile fibers to exhibit the sealing performance, high shielding performance can be obtained, so the amount of use of lubricating grease etc. for lubrication can be reduced accordingly, and even when the nut portion is provided with a lubricating grease supply mechanism, it can be simplified. Since the wet sealing member containing grease is arranged opposite to the groove portion in a spiral shape over a length that can make one or two turns, the space for the grease supply mechanism can be saved, and the nut portion or the retainer portion can also be miniaturized.

[0031] In addition, by making each filament of the pile fiber into a multi-filament in a crimped state, the surface area per pile fiber can be increased, and grease can be easily entangled between the pile fibers and a large amount can be retained. Therefore, it is possible to maintain the shielding property for a long time as a supply source for supplying the lubricant for a long time.

[0032] Furthermore, when the cut pile is a fabric, it is easy to ensure sufficient thickness for the base fabric of the cut pile, so that grease can be sufficiently retained in the base fabric. Therefore, it becomes possible to supply the lubricant for sealing to the pile fibers for a longer period, and even if the replacement frequency of the sealing material is reduced, the sealing property is less likely to deteriorate, contributing to the long life of the sealing material and the ball screw.

Brief Description of the Drawings

[0033]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0034] Embodiments of the present invention will be specifically described below with appropriate reference to the description of examples and drawings. In the test of the ball screw of the present invention, a retainer type ball screw was used. Of course, even if it is a simple nut part, there is no big difference, so the mode of the ball screw is not limited and interpreted by the description. In addition, in some of the tests comparing the differences in materials and fibers, the results of the tests using a linear guide are referred to. However, even when a sealing material is used at the end of the nut part to ensure the sealing performance with the groove part of the male screw shaft of the ball screw as in the present invention, it shows the same tendency as the case of the sealing performance with the rail of the linear guide. Therefore, these data are referred to and shown. Examples

[0035] <Test Example 1: Confirmation of Grease Retaining Property and Grease Supply Force of Pile Fabric and Pile Knitting in Wet End Sealing Material>

[0036] <Materials and Methods>

[0037] ·Regarding the evaluation pile In evaluating the grease retention and sealing properties of pile fabrics and pile knitted fabrics in a wet end seal material for a linear motion mechanism, a total of five types were selected as the pile fabrics and pile knitted fabrics to be used in the wet end seal material. The details of the selected pile fabrics and pile knitted fabrics are shown in Table 1 below.

[0038]

Table 1

[0039] The pile in the P-type pile fabric in Table 1 uses a single type of straight pile fiber for the raised pile fiber. Among the selected pile fabrics and pile knitted fabrics, it has a large fiber diameter. The density is 378,000 per square inch. And the ground yarn part of the base fabric for fixing the pile is a fabric made of weft yarn (nylon / heat-sealing yarn) and warp yarn (nylon), and it is a warp and weft double weave consisting of two layers, the surface layer and the back layer. In order to reduce the shedding of cut pile, an acrylic emulsion is penetrated into the ground yarn part of the base fabric from the back side.

[0040] The pile in the C-type pile fabric has crimp properties using hollow fibers and porous fibers. The raised pile fiber is a blend of a single type of 3.0 denier Biosafe, 1.5 denier Aqualon, and 1.5 denier rayon. The density is 316,500 per square inch. And the ground yarn part of the base fabric for fixing the pile is a fabric made of weft yarn (polyester) and warp yarn (polyester / rayon), and it is a warp and weft double weave consisting of two layers, the surface layer and the back layer. In order to reduce the shedding of cut pile, an acrylic emulsion is penetrated into the ground yarn part of the base fabric from the back side. By using hollow and porous fibers, the surface area of the pile increases compared to that using straight pile fibers of the same fiber diameter.

[0041] The pile in the G-type pile fabric has the same shrinkability as that of the C-type. Half of the pile rows are made of shrinkable piles using C-type hollow fibers and porous fibers, and the remaining half of the pile rows are made of shrinkable piles using ordinary fibers that are not hollow or porous. There are two types of raised pile fibers, and one type of pile fiber is alternately fixed to the weft of the ground yarn part that serves as the base fabric one by one. The first row of pile is a blended yarn of 3.0 denier Biosafe, 1.5 denier Aqualon, and 1.5 denier rayon. The second row of pile consists of a blended yarn of 3.0 denier Bulky, 3.0 denier Regular, and 1.5 denier rayon. The fiber density is 276,675. And the ground yarn part of the base fabric that fixes the pile is a fabric made of weft (polyester) and warp (polyester / rayon), and it is a warp and weft double weave consisting of two layers, the surface layer part and the back layer part. In order to reduce the shedding of cut pile, an acrylic emulsion is penetrated into the ground yarn part of the base fabric from the back side. By comparing the G-type pile fabric with the C-type pile fabric, it is confirmed to what extent making the fibers used for the pile hollow and porous contributes to the grease retention property and the grease supply power.

[0042] The pile in the T-type pile fabric is a curled pile made of multifilaments using filaments with a profiled cross-section whose outer periphery is split like a * shape. It has the highest density among the selected pile fabrics and pile knitted fabrics. Although it is complicated and expensive because the fibers are split, the surface area is increased compared to those using hollow and porous fibers, so the grease retention property and the supply power are high.

[0043] Note that the pile length in each type of pile used in the test is 3.3 mm.

[0044] The pile in the B-type pile knitted fabric uses a pile having a shrinkability using ordinary fibers. Due to the nature of knitting, the pile length cannot be increased, and the thickness of the pile is thinner compared to that of other P-type, C-type, G-type, and T-type pile fabrics. The pile length of the pile used in the test is 2.3 mm.

[0045] · Regarding felt Regarding the evaluation of the grease retention and sealing properties of the pile fabric and pile knitted fabric in the wet end seal material for the linear motion mechanism, in order to compare with the evaluation pile, felt (polyester felt, 3 mm thick, density 0.2 g / cm 2 , heat-resistant temperature 0~120°C) is used.

[0046] · Regarding grease In the evaluation of the piles and felts of each lip, lithium stearate grease (consistency No. 1~No. 3) was used respectively. In addition, in order to evaluate the C-type pile, further, molybdenum compound-containing grease (Mo-based) with a consistency of No. 2, urea-based grease (urea-based) with a consistency of No. 2, and fluorine oil were used for comparison.

[0047] · Regarding the grease retention evaluation method

[0048] Next, the grease retention of each of the above-mentioned pile fabrics and pile knitted fabrics is evaluated by the following evaluation method.

[0049] The evaluation sample is created according to the following procedure.

[0050] Cut out two pieces of the selected evaluation pile, each 1 cm square. On a metal plate that will serve as a measurement terminal, 200 mm × 30 mm square, attach the two cut-out pieces of the evaluation pile using double-sided tape, keeping a space between them so that the distance between the centers of each pile is 150 mm, and measure the weight at the time of drying (dry weight) before applying the grease. Apply the above-mentioned grease to the attached evaluation piles using a grease gun until the impregnation limit amount, and measure the weight (weight after application). The impregnation limit amount is judged visually. Record the weight after application - dry weight as the application amount of the grease.

[0051] Prepare an evaluation machine in which a disk made of aluminum with a diameter of about 200 mm is installed on a turntable whose rotation speed can be arbitrarily set, with the center of the disk aligned with the center of the turntable. Place the metal plate that serves as the measurement terminal with the two pieces of the evaluation pile to which the above-mentioned grease is applied, with the midpoint between the two pieces of the evaluation pile aligned with the center of rotation of the aluminum disk with a diameter of about 200 mm, facing downward so that the pile of the evaluation pile contacts the aluminum disk with a diameter of about 200 mm. While applying a load of 30 N as the total value to the two measurement terminals to which the evaluation pile is attached from above the metal plate that serves as the measurement terminal, rotate the turntable of the evaluation machine at a sliding speed of 500 mm / second for 5 minutes.

[0052] After stopping the rotation, remove the metal plate that serves as the measurement terminal with the two pieces of the evaluation pile to which the grease is applied, and measure its weight (weight after sliding). Record the weight after application - weight after sliding as the outflow amount of the grease.

[0053] Furthermore, perform the evaluation in the same manner as above, except that felt is used instead of the evaluation pile and grease other than lithium stearate grease (consistency No. 2) is used.

[0054] <Results> The evaluation results are shown in Table 2-1 and Table 2-2 below.

[0055]

Table 2-1

[0056]

Table 2-2

[0057] From the results shown in these tables, the following was found regarding the grease retention and grease supply properties.

[0058] The impregnation limit amount of grease differed depending on the properties of the pile used. And, even though the pile with crimpability had a larger surface area and a lower density, the impregnation limit amount of the applied grease was larger, and a larger amount of grease could be retained in the pile. It is understood that the crimp type pile has higher grease retention than the straight hair type pile.

[0059] Also, the impregnation limit amount of grease between fibers with crimpability differed depending on the difference in pile density. And, between fibers with crimpability, as the pile density increased, the surface area increased and the grease impregnation limit amount increased, and a larger amount of grease could be retained in the pile. When using fibers with crimpability, it is understood that a higher pile density has higher grease retention than a lower pile density.

[0060] The amount of grease outflow also differed depending on the properties of the pile used. And, it became clear that the pile using fibers with crimpability had a larger amount of grease outflow than the pile using straight hair fibers. It is understood that the straight hair type pile allows more grease to flow out in a shorter time than the crimp type pile, resulting in an excessive grease supply amount and a shorter grease supply possible time.

[0061] And for the P-type pile with straight hair, the surface area was small and the grease could not be retained, resulting in the largest amount of grease outflow. On the other hand, for the C-type and G-type piles with a crimped type, hollow porous fibers were used for some or all of the fibers, and due to the further crimping, the surface area increased, and it was considered that the grease retention amount increased. And from the results confirmed for the C-type with a crimped type, it was found that not only lithium-based greases such as lithium stearate grease, but also urea-based greases and molybdenum-based greases show equivalent characteristics regarding grease retention and grease supply. On the other hand, for the B-type, although the pile thickness was thin, the impregnation limit amount was small, and the density was low, there was no tendency for the outflow amount to increase dramatically compared to other crimped types.

[0062] From the above, by using hollow porous fibers in the pile used for the wet end seal material for the linear motion mechanism to increase the surface area, it is possible to increase the amount of grease retained in the pile, make the retained grease less likely to flow out, suppress excessive grease supply, and ensure a longer grease supply possible time.

[0063] In actual use, it is difficult to replenish the grease on the pile of the wet end seal material for the linear motion mechanism during use, and since it is used continuously for a longer time, it is preferable to use the C-type or T-type with a small amount of grease outflow in a certain period and with the grease supply being able to continue for a longer period.

[0064] On the other hand, when using fluorine oil, its viscosity is significantly lower than that of the above-mentioned lithium grease, molybdenum compound-containing grease, and urea-based grease. Therefore, the limit amount of oil impregnation is 340 mg, and impregnation more than four times is possible. However, the amount of fluorine oil flowing out is large, and more than 60% of the impregnated amount flows out, resulting in less than 40% of the oil remaining in the pile. As a result, compared with the above-mentioned lithium grease, molybdenum compound-containing grease, and urea-based grease, the amount of oil remaining in the pile is small, and there are problems with durability. In addition, there is a concern that the low-viscosity fluorine oil may leak into the linear motion mechanism device, mix with other lubricants, reduce the expected performance, or cause malfunction.

[0065] <Test Example 2: Confirmation of Seal Performance in Wet End Seal Material Unit>

[0066] <Materials and Methods>

[0067] ·Regarding the evaluation method Seal materials are attached to both ends of the linear guide, and the seal performance is measured after sliding at a specified speed and for a specified time.

[0068] The pile used is the same as that used in Test Example 1. Furthermore, for comparative study, instead of this pile, a current product using an end seal with a nip made of an elastomer material and the same felt as that used in Test Example 1 are used for the test.

[0069] A pile with a width of 5 mm formed into the outer peripheral shape of the linear guide is attached to the plate attached to the end of the linear guide, and lithium stearate grease (consistency No. 2) is used as the applied grease. The amount of grease applied to the pile is 4 mg / cm 2 so as to create an evaluation sample of the seal material. For type C piles, samples coated with the fluorine oil used in Test Example 1 instead of lithium stearate grease (consistency No. 2) are also created.

[0070] Then, while bending the pile so as to close the gap between the rail and the support frame of the pile with the thickness of the sealing material created at both ends of the linear guide being 2.0 mm, the pile is brought into contact with the rail and the support frame of the pile. Further, paper dust is enclosed in a box between the sealing material provided at both ends of the linear guide and the rail and set. For the C-type pile, a pile with toner enclosed in a box instead of paper dust is created and set in the same manner.

[0071] Thereafter, in order to investigate the sealing property of the sealing material against paper dust or toner when the linear guide slides, the linear guide is slid under the condition of continuously following at a maximum speed of 400 mm / second and an evaluation time of up to 24 hours, and the leakage of paper dust or toner and the degree of intrusion of paper dust or toner into the pile in the sealing material are confirmed.

[0072] Stop when the paper dust or toner penetrates through the pile with a width of 5 mm and leaks out. If the paper dust or toner does not leak out, measure the amount of paper dust or toner that has penetrated into the fibers of the wet pile constituting the sealing material and evaluate it as the sealing property. If the penetration amount reaches 5 mm or more and the paper dust or toner leaks out, record that the paper dust or toner leakage has occurred to an unacceptable level for practical use (record as × in the table).

[0073] <Results> The evaluation results are shown in Table 3-1 and Table 3-2 below.

[0074]

Table 3-1

[0075]

Table 3-2

[0076] When grease is not applied to the pile, in any condition, paper dust or toner leaked through the pile with a width of 5 mm. On the other hand, when grease was applied to the pile, it was confirmed that no paper dust leakage occurred even when continuously sliding for 24 hours. Therefore, it is understood that the sealing performance of paper dust imparted by applying grease to the pile is very high.

[0077] And the sealing performance varies depending on the characteristics of the pile used. It was found that the straight hair type pile has lower sealing performance and a greater degree of intrusion into the pile compared to the crimped type pile. Since the straight hair type pile does not have crimpability, gaps are generated between the fibers, which is considered to make paper dust leakage likely to occur. In order to ensure the sealing performance of the straight hair type, it is possible to respond by setting the width of the Gap between the guide rail of the linear guide and the sealing material to be narrower. However, there is a demerit that the sliding resistance increases.

[0078] It was found that the sealing performance of paper dust of the sealing material using the crimped type pile varies depending on the type of pile used. In the G type, when the width of the Gap widened to 2.3 mm, the amount of paper dust intrusion into the pile increased and paper dust leakage occurred. Since the G type has less grease retention compared to the C type and T type, an incomplete sealing part occurred, and as a result, it is considered that paper dust leakage occurred. When the Gap width was 1.5 mm with the C type with retained grease, good sealing performance was exhibited for both paper dust and toner. On the other hand, since the T type has a high density, the amount of paper dust intrusion is low under any condition.

[0079] Regarding the pile biting, bending the tip of the cut pile so as to close the gap between the rail and the support frame and making it contact the rail and bite into the rail tends to have higher overall sealing performance. Especially for C-type and G-type, the sealing effect by biting the pile becomes greater. However, if the Gap width is set to 2.3 mm and only the pile tip is bitten, the sealing performance does not increase and the effect becomes weak. Also, it was found that when the Gap width is set to 1.5 mm - 2.0 mm and it is bitten firmly, it is possible to improve the sealing performance even for low-density piles. In the case of B-type, in this test where the Gap width was narrowed to 1.5 mm due to the thin pile thickness in its configuration, sufficient sealing was not achieved. However, it is understood that if the Gap width is further narrowed, it can be expected to exhibit sealing performance.

[0080] On the other hand, in the current end seal, paper dust leaked out from the surface and sealing could not be achieved.

[0081] Also, when using felt, compared with piles, the transition of the increase in the repulsive load is faster, and the usable region as the Gap width is narrow, so it is difficult to adjust the attachment, and it has been clarified that even if attached, it will cause an increase in torque (Figure 3). Also, regarding the sealing performance, it has been clarified that leakage occurs from the corners of the felt and it is not suitable as a sealing material.

[0082] From the above, it has become clear that the crimped type fibers have higher sealing performance from the perspective of sealing performance, can supplement the sealing performance by biting, and can create a more inexpensive sealing material.

[0083] <Test Example 3: Confirmation of Sliding Resistance in Wet End Sealing Material Unit>

[0084] <Materials and Methods>

[0085] ·Regarding the evaluation method Attach a sealing material to both ends of the linear guide, and measure the resistance value after sliding at a specified speed and for a specified time.

[0086] The same pile as that used in Test Example 1 was used. A pile with a width of 5 mm formed into the outer peripheral shape of the linear guide was attached to a plate attached to the end of the linear guide, and lithium stearate grease (consistency No. 2) was used as the applied grease, and the amount of grease applied to the pile was 4 mg / cm 2 and applied so that it became. A sealing material serving as an evaluation sample was created. Then, the sealing materials created at both ends of the linear guide were brought into contact with each other while bending the pile so as to close the gap between the rail and the support frame of the pile with the thickness of the gap between the rail and the support frame of the pile being 2.0 mm.

[0087] After that, the maximum speed of the linear guide was set to 400 mm / second and the evaluation time was set to 30 minutes, and it was continuously driven and then stopped. The linear guide was pushed with a force gauge terminal, and the value of the sliding resistance was measured.

[0088] <Results> The evaluation results are shown in Table 4 below.

[0089]

Table 4

[0090] From the results shown in these tables, the following was found regarding the sliding resistance in the end sealing material for the linear motion mechanism.

[0091] As a general tendency, it became clear that when the pile was impregnated with grease to form a wet end sealing material, the sliding resistance decreased compared to the case where the pile was not impregnated with grease. Also, it was found that by pressing the pile against the linear guide rail and engaging it, the sealing performance improved, but on the other hand, the sliding resistance increased.

[0092] The end sealing material for the linear motion mechanism using the P-type pile which is a straight hair type had less resistance to the linear guide rail because it used straight hair fibers, and the sliding resistance was low.

[0093] End sealing materials for linear motion mechanisms using pile fibers of C-type and G-type, which are of the crimped type, have similar sliding resistances because the fiber forms are similar. However, due to the difference in density, the sliding resistance of the G-type is slightly lower.

[0094] The T-type, which is of the crimped type, has good sealing performance due to its high density. However, due to the use of fibers with crimpability using split fibers, its sliding resistance is higher than that of others.

[0095] For the B-type, since the Gap is 2.0 mm with respect to the pile thickness of 2.3 mm, the pile yarn only slightly penetrates into the linear guide rail. Generally, the sliding resistance is low, and there is no condition for the sliding resistance to increase.

[0096] As a comparison, even for the end seal of the current product, assuming actual use, the same test was conducted and evaluated only under the condition with grease. However, since the end seal of the current product uses an elastomer material, the resistance due to the lip is large, and the sliding resistance is larger compared to the case of using pile fibers.

[0097] From the above, it is understood that a high sliding resistance has an effect on the sealing performance. However, from the results of the test examples using pile fibers of C-type and G-type, it is possible to ensure sufficient sealing performance even with a low sliding resistance by biting the pile fibers into the linear guide rail.

[0098] <Test Example 4: Confirmation of Sealing Performance in Ball Screws> From the results of each of the above Test Example 1, it was found that an end sealing material made of wet cut pile with grease pre-retained between the pile fibers of the cut pile can effectively ensure sufficient sealing performance even with a low sliding resistance. The tip parts of the cut pile with grease pre-retained between the pile fibers bend to abut against the rail so as to close the gap between the rail and the support frame.

[0099] By the way, in a ball screw, unlike a linear motion mechanism in which most of the gaps to be filled are composed of smooth surfaces, the gap shape is composed of more complex curved surfaces. However, similar to the linear motion mechanism, it is necessary to prevent the mixing of powder and foreign matter, and it is required to exhibit sealing performance. As a sealing material for conventional products, a brush seal composed of a brush formed into a ring shape is used, but there is no product that can sufficiently ensure the sealing performance of the ball screw groove portion.

[0100] Therefore, even in a ball screw with a more complex gap shape with the support frame body, a test was conducted to confirm whether it is possible to ensure sufficient sealing performance by bending the tip portions of cut pile in which grease is held in advance between the pile fibers along the ball screw so as to close the gaps.

[0101] <Materials and Methods>

[0102] ·Regarding the evaluation method Attach a sealing material to the end of the ball screw, and evaluate the sealing performance after sliding at a specified speed and for a specified time by the amount and distribution of toner remaining on the surface of the rail groove portion of the ball screw.

[0103] A male screw shaft having an arc-shaped continuous groove portion and a nut portion are screwed together via a large number of steel balls inserted between the male screw and the female screw, and the nut is sent back and forth on the male screw shaft. A ball screw, an end sealing material in which a C-type pile spirally arranged on the inner circumference of the support frame body so as to face the groove portion over a length of one rotation or more of the outer circumference of the male screw shaft attached to the front or rear of the nut portion of the ball screw, and a C-type pile for spirally arranging on the inner circumference of the support frame body so as to face the groove portion over a length of one rotation or more of the outer circumference of the screw shaft at an equal pitch to the groove portion of the ball screw are prepared.

[0104] A C-type pile is disposed on the inner circumference of the support frame such that the outer circumference of the screw shaft faces the groove portion over a length of at least one rotation. Then, lithium stearate grease (consistency No. 2) is applied to the C-type pile as applied grease so that the amount of grease applied to the pile is 4 mg / cm 2 and, after applying it so as to be, a plate is snap-fitted and fixed to the insertion end face as a pile retaining means to form an end seal material as an evaluation sample, and then it is attached in front of or behind the ball screw nut portion.

[0105] Thereafter, toner (particle size: 5 μm) is sprinkled on the groove portion of the ball screw, and then the ball screw is reciprocated 10 times by hand sliding and then stopped, and the amount and distribution of the toner remaining on the surface of the rail groove portion of the ball screw are confirmed.

[0106] Furthermore, a test is conducted in the same procedure except that a brush seal formed in a ring shape for a conventional ball screw is used instead of the end seal material serving as the evaluation sample as a comparison target, and the amount and distribution of the toner remaining on the surface of the rail groove portion of the ball screw are confirmed.

[0107] <Result> As a result of the evaluation, when using the end seal material using the wet pile of the present invention, even if the surface to be sealed is composed of a substantially curved surface that is recessed in an arc shape like the groove portion of the ball screw, fine powder of toner does not remain everywhere, and the sealing performance of the groove portion that becomes the valley portion of the ball screw is sufficiently ensured, and it was confirmed that a result was obtained in which it is considered that no toner has invaded the bearing that is a rolling element.

[0108] Moreover, in the present invention, the pile tip portion is bent and contacts so as to fill the gap between the pile and the ball screw, particularly the groove portion of the ball screw, and is arranged in a spiral shape so as to contact the bearing which is a rolling element. As a result, while the toner fine powder is swept out by the pile and its tip portion, the lubricant previously held between the pile fibers prevents the intrusion of the toner fine powder, and it has been confirmed that the sealing is effectively achieved to an extent that could not be achieved by the conventional technology. In ball screws of various shapes, it is understood that the pile material used in the present invention follows the ball screw and uniformly contacts without contact leakage, and further, by using the lubricant previously held between the pile fibers, a sweeping effect and a sealing effect against fine powder such as toner can be obtained.

[0109] On the other hand, in the current brush seal which is a conventional product, fine powder of toner remains in a band shape at various locations of the ball screw. In particular, fine powder of toner remains in a band shape in the groove portion where the bearing which is a rolling element contacts, and furthermore, lumps of toner remain in some places. It has been confirmed that in the current brush seal which is a conventional product, the sealing property of the ball screw groove portion cannot be ensured, and toner has occurred on the bearing which is a rolling element.

[0110] The current brush seal is a brush formed in a ring shape. Since the brush does not uniformly contact the ball screw, it is considered that there will be a portion where the brush does not touch. Therefore, when observing the contact situation between the current brush seal and the ball screw in detail, it has been confirmed that there is a portion where the brush bends due to the height difference between the groove portion and the ridge portion of the ball screw and does not contact the groove portion at all. In the current brush seal, when the surface to be sealed is composed of a substantially curved surface such as the groove portion of the ball screw, it can be seen that it is difficult to seal the target surface from foreign matters.

Explanation of Signs

[0111] 1 Support frame arranged on the outer periphery of the male screw shaft of the divided ball screw 2 Wet seal member including grease arranged opposite to the spiral groove portion of the ball screw A plate fixed to a support frame body arranged on the outer periphery of a male screw shaft of a ball screw as a retaining means for a wet seal member including grease arranged to face a groove portion in a spiral shape of the 3-ball screw A support frame body arranged on the outer periphery of a male screw shaft of a 4-ball screw A wet seal member including grease in which a pile is cut in a stripe shape along a groove portion in a spiral shape of a ball screw so as to face the groove portion in a spiral shape of the 5-ball screw

Claims

1. In a ball screw in which a male screw shaft having an arcuate continuous groove portion and a nut portion are screwed together via a large number of steel balls inserted between the male screw and the female screw, and the nut is fed back and forth on the male screw shaft, an end seal member attached to the front or rear of the nut portion is a support frame body disposed on the outer periphery of the male screw shaft, a base cloth portion having a back surface fixed to the inner peripheral surface of the support frame body, having cut piles protruding from the surface of the base cloth portion toward the groove portion, the cut piles are spirally arranged on the inner periphery of the support frame body so as to face the groove portion over a length of one or more revolutions of the outer periphery of the male screw shaft, the tip portions of the cut piles are bent so as to close the gap between the groove portion and the support frame body and contact the groove portion, and a lubricant is previously held between the pile fibers of the cut piles. An end seal member made of wet cut piles, characterized in that.

2. The lubricant held between the pile fibers of the cut piles is grease having a consistency number of No. 1 to No. 4 in JIS K2220. The end seal member according to claim 1, characterized in that.

3. The grease is any one of lithium grease, molybdenum compound-containing grease, and urea-based grease. The end seal member according to claim 2, characterized in that.

4. The pile length of the cut piles is 2 mm or more. The end seal member according to any one of claims 1 to 3, characterized in that.

5. The pile fibers of the cut piles are composed of crimped multifilament fibers. The end seal member according to any one of claims 1 to 4, characterized in that.

6. The cut piles are made of a woven fabric. The end seal member according to any one of claims 1 to 5, characterized in that.

7. The cut piles are made of a knitted fabric. The end seal member according to any one of claims 1 to 5, characterized in that.

8. A ball screw provided with a male screw shaft, a nut portion, and steel balls, in which the end seal member according to any one of claims 1 to 7 is detachably and replaceably fixed to the front and rear of the nut portion.

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