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c 3 c-3 Linear B ush Linear Bush Structure and Features LM shaft Retainer Nut Ball Seal 日本特許番号第2607993号 Linear Bush model LM is a linear motion system used in combination with a cylindrical LM shaft to perform infinite linear motion. The balls under a load are in point contact with the LM shaft. This allows linear motion with minimal friction resistance and achieves highly accurate and smooth motion despite, the small permissible load. The nut uses high-carbon chromium bearing steel and its outer and inner surfaces are ground after being heat-treated. ●Interchangeability Since the dimensional tolerances of the Linear Bush's components are standardized, they are interchangeable. The LM shaft is machined through cylindrical grinding, which can easily be performed, and it allows highly accurate fitting clearance to be achieved. ●Highly accurate retainer plate Since the retainer, which guides three to eight rows of balls, is integrally molded, it is capable of accurately guiding the balls in the traveling direction and achieving stable running accuracy. Small-diameter types use integrally molded retainers made of synthetic resin. It reduces noise generated during operation and allows superb lubrication. ●Wide array of types A wide array of types are available, such as standard type, clearance-adjustable type, open type, long type and flanged LM case unit, allowing the user to select a type that meets the intended use. Fig. 1 Structure of Linear Bush Model LM … UU c-4 Applications The Linear Bush is used in a wide array of applications such as precision equipment including OA equipment and peripherals, measuring machines, automatic recorder and digital 3D mea- surement machine, and the slide units of industrial machinery including multi-axis drilling machine, punching press, tool grinder, automatic gas cutting machine, printing machine, card selector and food packing machine. c. Dimensions of the Linear Bush c-5 Linear B ush c 5 With the Linear Bush nut having the most accurate cylindrical shape, this type is widely used. There are two series of the Linear Bush in dimen- sional group. Type LM ……………Millimeter-dimension series used most widely in Japan Type LM-MG………Stainless steel version of type LM Type ME……………Millimeter-dimension series com- monly used in Europe Types and Features Standard Type Open Type Long Type Containing two units of the standard retainer plate, this type is optimal for loca- tions where a moment load is present and reduces man-hours in installation. Model LM-L ……… standard type The nut is partially cut open by one row of balls (50 t゜o 80 )゜. This enables the Linear Bush to be used even in locations where the LM shaft is supported by a column or fulcrum. In addition, a clearance can easily be adjusted. Types LM-OP/LME-OP Type LM-MG-OP Seal Type Clearance-adjustable Type This type has the same dimensions as the standard type, but the nut has a slit in the direction of the LM shaft. This allows the linear bush to be installed in a housing whose inner diameter is adjustable, and enables the clearance between the LM shaft and the housing to easily be adjusted. Models LM-AJ/LME-AJ Model LM-MG-AJ This type has the same dimensions as the standard type, but a special synthetic rubber seal is incorporated into both ends or either end of the linear bush, thus to prevent foreign matter from entering the linear bush and minimize leaking of the grease. Models LM … UU/LME … UU/LM … MGUU (The symbol for type with its one side having a seal: "U") A seal is also available for some of the clearance- adjustable types and the open types. c-6 The nut of the standard type Linear Bush is integrated with a flange. This enables the Linear Bush to be directly mounted onto the housing with bolts, thus achieving easy installation. Model LMF ………… standard type Model LMF-M ……… made of stainless steel Flanged Type (Circular) Flanged Type (Circular) - Long Flanged Type (Square) Flanged Type (Small) The nut is integrated with a small flange. Since the height is lower than model LMK, compact design is allowed. Since the rows of balls in the Linear Bush are arranged so that two rows receive the load from the f lat side, a long service l i fe can be achieved. Model LMH ……… standard type Flanged Type (Small) - Long The flange is smaller and lower than model LMK-L, allowing compact design. Containing two units of the standard retainer plate, this type is optimal for locations where a moment load is present. Since the rows of balls in the Linear Bush are arranged so that two rows receive the load from the flat side, a long service life can be achieved. Model LMH-L ……… standard type Flanged Type (Square) - Long Like model LMF-L, this type also has a flange, but the flange is cut to a square shape. Since the height is lower than the circular flange type, compact design is allowed. Model LMK-L ………… standard type Model LMK-ML ……… made of stainless steel Like model LMF, this type also has a flange, but the flange is cut to a square shape. Since the height is lower than the circular flange type, compact design is allowed. Model LMK ………… standard type Model LMK-M ……… made of stainless steel The nut of the long type Linear Bush is inte- grated with a flange. This enables the Linear Bush to be directly mounted onto the hous- ing with bolts, thus achieving easy installa- tion. Containing two units of the standard retainer plate, this type is optimal for loca- tions where a moment load is present. Model LMF-L ………… standard type Model LMF-ML ……… made of stainless steel c. Dimensions of the Linear Bush c-7 Linear B ush c 7 It is a case unit where the standard type of Linear Bush is incorporated into a small, lightweight aluminum casing. This model can easily be mounted simply by securing it to the table with bolts. LM Case Unit Type Model SC LM Case Unit Type Model SH LM Case Unit Type (Long) Model SL LM Shaft Support Type Model SK An aluminum-made light fulcrum for secur- ing an LM shaft. The LM shaft mounting section has a slit, enabling the linear bush to firmly secure an LM shaft using bolts. LM Case Unit Type (Long) Model SH-L A long version of model SH, this model is a case unit that contains two units of the standard type Linear Bush in an aluminum casing. A long version of model SC, this model con- tains two units of the standard type Linear Bush in an aluminum casing. It is a case unit where the standard type of Linear Bush is incorporated into a smaller and lighter aluminum casing than model SC. This model allows even more compact design than model SC. It also has flexibili- ty in mounting orientation. Additionally, it is structured so that two rows of balls receive the load from the top of the casing, allowing a long service life to be achieved. Flexibly mountable type Flexibly mountable type c-8 manufactures high quality, dedicated LM shafts for Linear Bush model LM series in short delivery time. Standard LM Shafts also manufactures hollow LM shafts and those LM shafts with their ends specially treated like ones shown in the photo at your request. Build-to-order LM Shafts c. Dimensions of the Linear Bush c-9 Linear B ush c 9 Accuracy Standards The accuracy of the Linear Bush in inscribed circle diameter, outer diameter, width and eccen- tricity is described in the corresponding dimensional table. The accuracy of model LM in inscribed circle diameter and eccentricity is classified into high grade (no symbol) and preci- sion grade (P) (accuracy symbol is expressed at the end of each model number). The accuracy of clearance-adjustment type (-A-J) and open type (-OP) in inscribed circle diam- eter and eccentricity indicates the value before division. Dedicated Shafts for Model LM The LM shaft of the Linear Bush needs to be manufactured with much consideration for hard- ness, surface roughness and dimensional accuracy of the shaft since balls roll directly on it. manufactures dedicated LM shafts for the Linear Bush. See the dimensional table for standard LM shafts on page c-11. Among other factors, the surface hardness of an LM shaft affects the service life of your Linear Bush system most significantly. Therefore, take much care in selecting a material and a heat treatment method when assembling the system. In addition, as the surface hardness of the LM shaft greatly affects the service life as stated above, use care in selecting and/or han- dling a material and heat treatment. ●Material Generally, the following materials are used as suitable for surface hardening through induction quenching. SUJ2 (JIS G 4805, high-carbon chromium bearing steel) SK3 to 6 (JIS G 4401, carbon tool steel) S55C (JIS G 4051, carbon steel for machine structural use) For special applications, martensitic stainless steel SUS440C, which is corrosion resistant, may also be used. ●Hardness We recommend surface hardness of 58 HRC (≒ 653 HV) or higher. The depth of the hardened layer is determined by the size of the Linear Bush; we recommend approximately 2 mm for gen- eral use. ●Roughness of the surface To achieve smooth motion, the surface should preferably be finished to 0.40a or less. c-10 ●Dimensions of a Hollow LM Shaft If a hollow LM shaft is required for purposes such as weight reduction, use the desired material from table 1 of dimensions of hollow LM shafts that keeps in stock. Models marked with "**" are build-to-order items. φd φd4 Table 1 Dimensions of Hollow LM Shafts Model No. LM 8 LM 10 LM 12 LM 13 LM 16 LM 20 LM 20 LM 25 LM 30 LM 35 **LM 38 LM 40 LM 50 LM 60 **LM 80 **LM 100 8 10 12 13 16 20 20 25 30 35 38 40 50 60 80 100 3 4 6 7 9 10 14 15 16 20 22 22 25 32 52.5 67.5 0.4 0.6 0.7 0.8 1.1 1.9 1.3 2.5 4 5.1 6 6.9 11.6 16 22.6 33.7 Unit: mm LM shaft outer diameter d Inner diameter d4 Mass （kg/m） c 11 c. Dimensions of the Linear Bush c-11 Linear B ush SF 3 SF 4 SF 5 SF 6 SF 8 SF 10 SF 12 SF 13 SF 16 SF 20 SF 25 SF 30 SF 35 SF 38 SF 40 SF 50 SF 60 SF 80 SF 100 LM 3 LM 4 LM 5 LM 6 LM 8, 8S LM 10 LM 12 LM 13 LM 16 LM 20 LM 25 LM 30 LM 35 LM 38 LM 40 LM 50 LM 60 LM 80 LM 100 3 4 5 6 8 10 12 13 16 20 25 30 35 38 40 50 60 80 100 ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ – 4 –12 – 2 – 8 – 5 –14 – 6 –17 – 7 –20 – 9 –25 –10 –29 –12 –34 Standard LM Shafts manufactures high quality, dedicated LM shafts for Linear Bush model LM series in short delivery time. ①・Major materials: THK5SP (THK standard material) SUJ2 (high-carbon chromium bearing steel) ①・Hardness: HRC58 to 64 ①・Hardened layer depth: 0.8 to 2.5 mm (varies with shaft diameter) ①・Surface roughness: 0.20a to 0.40a ①・Straightness of the LM shaft: 50μm/300 mm or less ② Precision-grade LM shafts with shaft diameter toler- ance of g5 or h5 are also manufactured as standard. ③ Corrosion-resistant, martensitic stainless steel LM shafts are also available. ④ When asking an estimate or placing an order, refer to the model number coding shown on the left. Model number coding SF25 g6 -500L K zModel number xLM shaft outer diameter tolerance cOverall LM shaft length (in mm) vSpecial symbol - no symbol: solid shaft; K : standard hollow shaft M: special material; F : with surface treatment *If two or more symbols are given, they are shown in an alphabetical order. z x c v L φd Shaft diameter Model No. Overall LM shaft length: L mm d 100 ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ 200 ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ 300 ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ 400 ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ 500 ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ○ ◎ ◎ 600 ◎ ◎ ◎ ◎ ◎ ◎ ◎ 700 ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ 800 ◎ ◎ ◎ ◎ ◎ ◎ ◎ ○ ◎ ◎ ○ ○ ○ 1000 ◎ ◎ ◎ ◎ ◎ ○ ◎ ◎ ○ ○ ○ 1200 ◎ ◎ ◎ ◎ ◎ 1300 ◎ ◎ ◎ ◎ ◎ ◎ ◎ 1500 ◎ ◎ ○ ◎ ◎ ○ ○ ○ 2000 ○ ○ ○ ○ ○ 3000 Supported modelToleranceg6μm Note: ◎ indicates standard stock; ○ indicates semi-standard stock. c-12 Specially Machined Types also supports special machining processes such as tapping, milling, threading, through drilling and joggling, as shown in the figure below, at your request. Table of Rows of Balls and Masses for Clearance- adjustable Types and Open Types of the Linear Bush Tapped for support Tapped KeywayJoggled FlatThreaded Shaft diameter 6 8 10 12 13 16 20 25 30 35 38 40 50 60 80 100 120 LM 6-AJ LM 8S-AJ LM 8-AJ LM 10-AJ LM 12-AJ LM 13-AJ LM 16-AJ LM 20-AJ LM 25-AJ LM 30-AJ LM 35-AJ LM 38-AJ LM 40-AJ LM 50-AJ LM 60-AJ LM 80-AJ LM 100-AJ LM 120-AJ 4 4 4 4 4 4 5（4） 5 6（5） 6 6 6 6 6 6 6 6 8 7.8 10 14.7 29 31 42 68 85 216 245 384 475 579 1560 1820 4320 8540 14900 Model No. Clearance-adjustable type Open type Rows of balls Massg — — — — LM 12-OP LM 13-OP LM 16-OP LM 20-OP LM 25-OP LM 30-OP LM 35-OP LM 38-OP LM 40-OP LM 50-OP LM 60-OP LM 80-OP LM 100-OP LM 120-OP — — — — 3 3 4（3） 4 5（4） 5 5 5 5 5 5 5 5 6 — — — — 25 34 52 69 188 210 350 400 500 1340 1650 3750 7200 11600 Model No. Rows of balls Massg Note: The numbers of ball rows in the table apply to types using a resin retainer. Those of types using a metal retainer are indicated in parentheses. c. Dimensions of the Linear Bush c-13 Linear B ush c 13 Selection by Service Environment ■Grease Lubrication When installing a type attached with seals on both sides (… UU) to the LM shaft, apply grease to rows of balls in the Linear Bush. When installing a standard type (without seal), perform the same as above or apply grease to the LM shaft. Afterward, replenish grease of the same type as necessary according to the service condi- tions. For grease, we recommend high-quality lithium-soap group grease No. 2. ●Lubrication The Linear Bush operates using grease or oil lubrication. ■Oil Lubrication Turbine oil, machine oil and spindle oil are commonly used. When oiling the Linear Bush, drop oil on the LM shaft, or infuse it from the greasing hole on the housing as shown in Fig. 2. Housing Spacer Fig. 2 ●Dust Prevention Entrance of dust or other foreign matter into the Linear Bush will cause abnormal wear or shorten the service life. When entrance of dust or other foreign matter is predicted, it is impor- tant to select an effective sealing device or dust-control device that meets the atmospheric conditions. For the Linear Bush, a special synthetic rubber seal that is highly resistant to wear and a felt seal (highly dust preventive with low seal resistance) are available as dust prevention acces- sories. In addition, produces round bellows. Contact us for details. ■Felt Seal Model FLM Linear Bush model LM series include types equipped with a special synthetic rubber seal (LM …UU, U). If desiring to have an additional dust prevention measure, or desiring to lower the seal resistance, use the felt seal model FLM (see table 5 on page c-20). c-14 Assembling the Linear Bush ●Housing Inner-diameter Dimensions Table 2 shows housing inner-diameter toler- ances recommended for the Linear Bush. When fitting the Linear Bush with the hous- ing, clearance fitting is normally recommend- ed. If the clearance needs to be smaller, pro- vide transition fitting. Table 2 Housing Inner-diameter Tolerance LM LME LMF LMK LMH LM-L LMF-L LMK-L LMH-L — High grade (no symbol) High grade (no symbol) Precision grade (P) Type Model No. Accuracy H7 H6 H7 H7 J7 J6 K6,J6 J7 Housing Clearance fitting Transition fitting ●Clearance between the Nut and LM Shaft When using the Linear Bush with an LM shaft in combination, normal clearance applies. If the clearance needs to be smaller, close clearance applies. Note 1: If the clearance after installation is to be negative, it is preferable not to exceed the radial clearance tolerance indicated in the dimensional table. Note 2: The tolerance of the shaft for case unit models SC, SL, SH and SH-L falls under high grade (no symbol). Table 3. Shaft Outer-diameter Tolerance LM LME LMF LMK LMH LM-L LMF-L LMK-L LMH-L High grade (no symbol) Precision grade (P) High grade (no symbol) — Type Model No. Accuracy f6，g6 f5，g5 h7 f6，g6 h6 h5 k6 h6 LM shaft Normal clearance Close clearance ●Material and Surface Treatment For the Linear Bush and the LM shaft, stainless steel types are available for some models. It is also possible to provide surface treatment to the LM shaft. However, surface treatment may not be suitable for some types. Contact for details. c. Dimensions of the Linear Bush c-15 Linear B ush c 15 ●Installing the Nut Although the Linear Bush does not require a large strength for securing it in the LM shaft direction, do not support the nut only with driving fitting. For the housing inner-diameter tolerance, see table 2. ■Installing the Standard Type Figures 3 and 4 show examples of installing the standard type Linear Bush. When securing the Linear Bush, use snap rings or stopper plates. Fig. 3 Snap Ring Fig. 4 Stopper Plate c-16 Model No. LM 3 4 5 6 8 8S 10 12 13 16 20 25 30 35 38 40 50 60 80A 100A 120A — — WR 10 12 — — 19 21 23 28 32 40 45 52 — — — — — — — — — 10 12 15 15 19 21 22 — — 40 45 52 56・58 60 80 90 120 （150） （180） AR 7 8 10 12 15 15 19 21 23 28 32 40 45 52 57 60 80 90 120 150 180 — — 10 12 15 15 19 21 — 28 32 40 45 52 — 60 80 90 120 — — Snap ring For outer surface Needle snap ring Needle snap ring C-shape snap ring C-shape snap ring For inner surface Snap Ring for Installation To secure Linear Bush model LM, snap rings indicated in table 4 are available. Note 1: For models indicated with parentheses, use C-shape concentric snap rings. Note 2: The table commonly applies to models LM, LM-GA, LM-MG and LM-L. Setscrews Not Allowed Securing the nut by pressing the outer sur- face with one setscrew as shown in Fig. 5 will cause the nut to be deformed. Setscrew Nut Housing Fig. 5 Table 4 Types of Snap Rings c. Dimensions of the Linear Bush c-17 Linear B ush c 17 ■Installing a Flanged Type With models LMF, LMK and LMH, the nut is integrated with a flange. Therefore, the Linear Bush can be mounted only via the flange. ■Installing a Clearance-adjustable Type To adjust the clearance of a clearance- adjustable type (-AJ), use a housing that allows adjustment of the nut outer diameter so as to facilitate the adjustment of the clearance between the Linear Bush and the LM shaft. Positioning the slit of the Linear Bush at an angle of 90 w゜ith the housing's slit will provide uniform deformation in the cir- cumferential direction (see Fig. 6). Nut mounted via socket and spigot joint Mounted via a flange only Fig. 6 ■Installing an Open Type For an open type (-OP), also use a housing that allows adjustment of the nut outer diam- eter as shown in Fig. 7. Open types are normally used with a light preload. Be sure not to give an excessive preload. Whirl-stop plate Whirl-stop plate Housing Adjustment bolt Fig. 7 c-18 ●Installing the Shaft Support Shaft support model SK can easi ly be secured to the table using mounting bolts. Model SK enables the LM shaft to firmly be secured using tightening bolts. Tightening bolt Mounting bolt Washer Reference surface THK SK30 ●Installing an LM Case Unit ■Attaching Model SC (SL) Since models SC and SL can be attached from the top or bottom by simply tightening it using bolts, the installation time can be short- ened (see Fig. 8). Fig. 8 ■Attaching Model SH (SH-L) Since models SH and SHL can be attached from the top or bottom by simply tightening it using bolts, the installation time can be short- ened (see Fig. 9). Fig. 9 Basic installation Alternative installation c. Dimensions of the Linear Bush c-19 Linear B ush c 1