Steel ball feeding device and working method thereof

Abstract

The present invention belongs to the field of conveying technology, and specifically relates to a steel ball unloading device and a working method thereof. The steel ball unloading device includes: a storage barrel for storing steel balls, and at least one discharge hole is provided at the bottom of the barrel; a feeding plate is provided with a material receiving groove on the surface facing the storage barrel; a driver is connected to the feeding plate; a picking and placing mechanism; a control module is electrically connected to the driver and the picking and placing mechanism, and is configured to control the driver to drive the feeding plate to move back and forth at the discharge hole and the transfer position to transfer the steel balls in the storage barrel, and is also configured to control the picking and placing mechanism to absorb the steel balls in the material receiving groove at the transfer position and place the absorbed steel balls into the product. The steel ball unloading device and its working method locate the position of the steel balls by arranging a positioning component in the material receiving groove, and at the same time, in the process of moving toward the transfer position, lubricating oil is sprayed on the steel balls by squeezing the oiling mechanism, and the steel balls are made to protrude from the material receiving groove at both the discharge hole and the transfer position.

Description

Technical Field

[0001] The present invention belongs to the field of conveying technology, and in particular relates to the transportation of balls, and in particular to a steel ball feeding device and a working method thereof. Background Art

[0002] During the assembly process, the steel balls are generally placed in the storage barrel. The movement of the picking plate causes the steel balls in the storage barrel to fall into the material trough of the picking plate, thereby transporting the steel balls.

[0003] In the related art, the steel balls need to be oiled. However, when the oiled steel balls follow the movement of the trough, an oil film is easily generated at the slot of the trough, thereby blocking the trough and causing the camera on the negative pressure suction mechanism to misjudge.

[0004] Therefore, how to solve the technical problem that the material trough is easily blocked by the oil film and causes the camera to misjudge is urgently needed to be solved by those skilled in the art.

[0005] It should be noted that the above information disclosed in this background technology section is only used to understand the background technology of the present application concept, and therefore, the above description is not considered to constitute information of the prior art. Summary of the Invention

[0006] The embodiments of the present disclosure at least provide a steel ball feeding device and a working method thereof.

[0007] In the first aspect, the embodiment of the present disclosure provides a steel ball unloading device, comprising: a storage barrel for storing steel balls, the bottom of which is provided with at least one discharge hole; a picking plate, the surface of which faces the storage barrel is provided with a material receiving groove; a driver connected to the picking plate; a picking and placing mechanism; a control module, electrically connected to the driver and the picking and placing mechanism, configured to control the driver to drive the picking plate to move back and forth between the discharge hole and the transfer position to transfer the steel balls in the storage barrel, and also configured to control the picking and placing mechanism to absorb the steel balls in the material receiving groove at the transfer position and transfer them The sucked steel balls are placed in the product; a positioning component is provided in the material holding trough, and the positioning component is connected to the oiling mechanism; wherein the positioning component is suitable for protruding the received steel balls out of the material holding trough at the discharge hole and the transfer position; in the process of the picking plate moving to the transfer position, the positioning component is stretched outward by the squeezing of the steel balls so that the steel balls are immersed in the material holding trough, and at the same time, the positioning component squeezes the oiling mechanism through the stretching action to spray lubricating oil on the steel balls, and the positioning component rotates the steel balls by pressing them against the storage barrel to evenly spread the lubricating oil.

[0008] In an optional embodiment, the material picking plate is inserted into a guide block; wherein the guide block is in contact with the lower surface of the storage barrel, and a material passage hole connected to the discharge hole is provided on the guide block; in the process of the material picking plate moving to the transfer position, the positioning assembly presses the steel ball against the guide block to rotate the steel ball.

[0009] In an optional embodiment, the depth of the material holding groove is greater than the diameter of the steel ball, so that the steel ball can sink into the material holding groove after expanding the positioning assembly.

[0010] In an optional embodiment, the positioning assembly includes: a plurality of positioning blocks, each of which is surrounded by a positioning groove; wherein when the material trough is located at the discharge hole or the transfer position, the steel balls received by the positioning groove protrude from the material trough.

[0011] In an optional embodiment, a plurality of guide shafts are provided in the material holding trough; a guide groove is provided on the positioning block, and the positioning block is sleeved on the guide shaft through the guide groove.

[0012] In an optional embodiment, a return spring is sleeved on the guide groove to bring the positioning blocks together to make the steel balls protrude from the material trough.

[0013] In an optional embodiment, the oiling mechanism is connected to the guide groove and is suitable for adding lubricating oil to the guide groove; an oil filling port connected to the guide groove is provided on the positioning block; wherein, the positioning block is suitable for stretching and squeezing the lubricating oil in the guide groove outward and spraying it out through the oil filling port.

[0014] In an optional embodiment, an oil hole is provided in the guide shaft; wherein one end of the oil hole is connected to the guide groove, and the other end is connected to the oiling mechanism.

[0015] In an optional embodiment, a plurality of oil drain holes are provided at the bottom of the material trough, and each oil drain hole corresponds to each positioning block; wherein when the material trough is located at the discharge hole or the transfer position, each positioning block blocks the corresponding oil drain hole.

[0016] On the second aspect, the embodiment of the present disclosure also provides a working method of the steel ball unloading device as described above, including: controlling the driver through the control module to drive the picking plate to move back and forth at the discharge hole of the storage barrel and the transfer position of the pick-up and placement mechanism to transfer the steel balls in the storage barrel; controlling the pick-up and placement mechanism through the control module to absorb the steel balls in the material trough at the transfer position, and placing the absorbed steel balls into the product; using the positioning component in the material trough to protrude the received steel balls out of the material trough at the discharge hole and the transfer position; and causing the oiling mechanism to spray lubricating oil onto the steel balls through the pressurized movement of the positioning component.

[0017] The beneficial effect of the present invention is that the steel ball unloading device and its working method locate the position of the steel ball by arranging a positioning component in the material trough, and at the same time, in the process of moving toward the transfer position, lubricating oil is sprayed on the steel ball by squeezing the oiling mechanism, and the steel ball is made to protrude from the material trough at both the discharge hole and the transfer position, so as to prevent the oil film from covering the material trough and causing the picking and placing mechanism to fail to grab the steel ball.

[0018] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description and the drawings.

[0019] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are specifically cited herein and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 A schematic structural diagram of a steel ball feeding device provided in an embodiment of the present disclosure;

[0022] Figure 2 A schematic cross-sectional view of a steel ball feeding device according to an embodiment of the present disclosure;

[0023] Figure 3 A schematic structural diagram of a positioning assembly in a material trough provided in an embodiment of the present disclosure;

[0024] Figure 4 A schematic diagram of the structure of a steel ball provided in an embodiment of the present disclosure when it is not under pressure in a material holding tank.

[0025] In the picture:

[0026] 1. Storage barrel; 11. Discharge hole;

[0027] 2. Reclaiming plate; 20. Guide block; 201. Feed hole; 21. Material trough; 22. Positioning assembly; 221. Positioning block; 222. Positioning slot; 223. Guide shaft; 224. Return spring; 225. Guide slot; 226. Oil filling port; 227. Oil drain hole; 228. Oil hole;

[0028] 3. Driver;

[0029] 4. Pick-up and place mechanism; 41. Material transfer position; 42. Suction tube;

[0030] 5. Steel balls;

[0031] 6. Grease mechanism. DETAILED DESCRIPTION

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0033] It should be noted that similar reference numerals and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings. In addition, in the drawings, the thickness of components may be exaggerated or reduced in order to effectively describe the technical content.

[0034] The following embodiments of the present invention are described in detail with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features therein may be combined with each other.

[0035] like Figure 1 As shown, at least one embodiment provides a steel ball unloading device, including: a storage barrel 1, a material picking plate 2, a driver 3, and a picking and placing mechanism 4.

[0036] Specifically, such as Figure 2 As shown, the storage barrel 1 is used to store steel balls 5, and at least one discharge hole 11 is opened at the bottom of the barrel.

[0037] Specifically, such as Figure 2 As shown, the material-taking plate 2 is inserted into a guide block 20, which is in contact with the lower surface of the storage barrel 1. A material passage hole 201 connected to the discharge hole 11 is provided on the guide block 20, and a material trough 21 adapted to the discharge hole 11 is provided on the surface of the material-taking plate 2 facing the storage barrel 1.

[0038] Specifically, such as Figure 2As shown, the driver 3 is connected to the picking plate 2, and can be but not limited to using a cylinder, which is used to drive the picking plate 2 to move, so that the material trough 21 on the picking plate 2 moves back and forth between the discharge hole 11 and the transfer position 41, thereby transferring the steel balls 5 in the storage barrel 1; when the driver 3 pushes the picking plate 2 to move so that the material trough 21 coincides with the discharge hole 11, the steel balls 5 in the storage barrel 1 fall into the material trough 21 through the discharge hole 11 and the feed hole 201, and when the driver 3 pushes the picking plate 2 to reset and move so that the material trough 21 is located at the transfer position 41, the steel balls 5 received by the material trough 21 are exposed to be grabbed by the pick-up and place mechanism 4.

[0039] Specifically, the picking and placing mechanism 4 absorbs the steel ball 5 at the transfer position 41 through negative pressure, then moves the steel ball 5 to the product where the steel ball 5 needs to be assembled through rotation, and finally places the steel ball 5 on the product where the steel ball 5 needs to be assembled through positive pressure; wherein, a camera is provided on the picking and placing mechanism 4 to determine whether there is a steel ball 5 in the material trough 21 through images.

[0040] like Figure 3 As shown, in some embodiments, a positioning assembly 22 is provided in the material holding trough 21 , and the depth of the material holding trough 21 is greater than the diameter of the steel ball 5 .

[0041] Specifically, when the steel ball 5 falls onto the positioning assembly 22 , the steel ball 5 protrudes from the material trough 21 , and then the driver 3 pushes the material picking plate 2 to move, so that the steel ball 5 is forced to squeeze the positioning assembly 22 and is completely located in the material trough 21 .

[0042] In this embodiment, when the steel ball 5 moves along with the material taking plate 2 , the positioning assembly 22 abuts against the plate covering the material trough 21 , thereby causing the steel ball 5 to roll.

[0043] like Figure 3 As shown, in some embodiments, the positioning assembly 22 includes: a plurality of positioning blocks 221 , each positioning block 221 surrounding and forming a positioning slot 222 .

[0044] In this embodiment, the positioning groove 222 is used to limit the position of the steel ball 5 so that the steel ball 5 is always located at the same position after entering the material trough 21, thereby facilitating the pick-and-place mechanism 4 to accurately grasp the steel ball 5.

[0045] like Figure 4 As shown, in some embodiments, each positioning block 221 is respectively sleeved on an independent guide shaft 223 , and each guide shaft 223 is sleeved with a return spring 224 .

[0046] Specifically, each positioning block 221 is pushed together by the corresponding return spring 224. At this time, the steel ball 5 falls on the positioning block 221 and protrudes out of the material trough 21; when the steel ball 5 is pressurized, the steel ball 5 squeezes each positioning block 221 backward, thereby completely submerging into the material trough 21.

[0047] like Figure 4 As shown, in some embodiments, a guide groove 225 is defined on the positioning block 221 , and the positioning block 221 is sleeved on the guide shaft 223 through the guide groove 225 .

[0048] like Figure 4 As shown, in some embodiments, the guide groove 225 is connected to the oiling mechanism 6 , and the positioning block 221 is provided with an oil filling port 226 connected to the guide groove 225 .

[0049] Specifically, the oiling mechanism 6 is used to add lubricating oil to the guide groove 225. When the positioning block 221 is forced to retreat, it squeezes the lubricating oil in the guide groove 225, so that the lubricating oil is sprayed from the oil filling port 226 onto the steel ball 5. Then, the lubricating oil can be evenly applied to the steel ball 5 through the rotation of the steel ball 5.

[0050] like Figure 4 As shown, in some embodiments, an oil hole 228 is provided in the guide shaft 223 , one end of the oil hole 228 is connected to the guide groove 225 , and the other end is connected to the oiling mechanism 6 .

[0051] Due to the presence of lubricating oil, the notch of the positioning groove 222 is easily covered by an oil film. After being covered by the oil film, the positioning groove 222 is a plane. At this time, the camera on the pick-and-place mechanism 4 is likely to make a misjudgment and recognize that there is no steel ball 5 in the positioning groove 222.

[0052] In order to solve the above problem, the positioning assembly 22 of this embodiment adopts an elastically arranged positioning block 221. After the positioning groove 222 is exposed, each positioning block 221 pushes the steel ball 5 to protrude from the positioning groove 222 to puncture the oil film, thereby being recognized by the camera on the pick-up and placement mechanism 4.

[0053] like Figure 4 As shown, in some embodiments, a plurality of oil drain holes 227 are provided at the bottom of the material trough 21 , and the oil drain holes 227 correspond to the positioning blocks 221 .

[0054] In this embodiment, when the positioning blocks 221 are close together, the oil drain hole 227 is blocked by the positioning blocks 221. When the steel balls 5 squeeze the positioning blocks 221, the oil drain hole 227 is opened, thereby preventing the residual lubricating oil in the oil drain hole 227 from being sucked away when the negative pressure of the picking and placing mechanism 4 sucks the steel balls 5.

[0055] like Figure 1 As shown, in some embodiments, the pick-and-place mechanism 4 includes: a suction tube 42 and an air pump connected to the suction tube 42 .

[0056] Specifically, the air pump generates negative pressure in the suction tube 42 to grab the steel ball 5, and the air pump generates positive pressure in the suction tube 42 to release the steel ball 5; the camera is set on the suction tube 42.

[0057] Specifically, the suction tube 42 is disposed on a turntable, and the control module is electrically connected to the turntable and the air pump, so that the suction tube 42 is rotated to a position above the product by controlling the rotation of the turntable.

[0058] At least one embodiment also provides a working method of a steel ball unloading device, including: controlling the driver 3 through the control module to drive the material picking plate 2 to move back and forth between the discharge hole 11 of the storage barrel 1 and the transfer position 41 of the pick-up and placement mechanism 4 to transfer the steel balls 5 in the storage barrel 1; controlling the pick-up and placement mechanism 4 through the control module to absorb the steel balls 5 in the material trough 21 at the transfer position 41, and placing the absorbed steel balls 5 into the product; using the positioning component 22 in the material trough 21 to protrude the received steel balls 5 out of the material trough 21 at the discharge hole 11 and the transfer position 41; and causing the oiling mechanism 6 to spray lubricating oil onto the steel balls 5 through the pressure movement of the positioning component 22.

[0059] Regarding the specific structure and implementation process of the steel ball feeding device, please refer to the relevant discussion in the above embodiment and will not be repeated here.

[0060] In summary, the steel ball unloading device and its working method locate the position of the steel ball 5 by setting a positioning component 22 in the material trough 21. At the same time, in the process of moving toward the transfer position 41, the lubricating oil is sprayed on the steel ball 5 by squeezing the oiling mechanism 6, and the steel ball 5 is made to protrude from the material trough 21 at the discharge hole 11 and the transfer position 41 to prevent the oil film from covering the material trough 21 and causing the picking and placing mechanism 4 to fail to grab the steel ball 5.

[0061] Herein, when it is mentioned that a first component is located on a second component, this may mean that the first component may be directly formed on the second component or a third component may be interposed between the first component and the second component.

[0062] As used herein, when an element or layer is referred to as being "located on," "engaged to," "connected to," "attached to," or "coupled to" another element or layer, it may be directly located on, engaged, connected, attached to, or coupled to the other element or layer, or there may be intervening elements or layers. Conversely, when an element is referred to as being "directly on," "directly engaged to," "directly connected to," "directly attached to," or "directly coupled to" another element or layer, there may be no intervening elements or layers. Other words used to describe the relationship between elements should be interpreted in a similar manner (e.g., "between" versus "directly between," "adjacent" versus "directly adjacent," etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0063] Herein, example embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. As used herein, expressions such as "at least one of..." when following a list of elements modify the entire list of elements, rather than modifying individual elements in the list. For example, the expression "at least one of a, b, and c" should be understood to include only a, only b, only c, both a and b, both a and c, both b and c, or all of a, b, and c.

[0064] The terms used herein are only used to describe specific exemplary configurations and are not intended to be limiting. As used herein, the singular articles "a", "an" and "the" may also be intended to include plural forms, unless otherwise clearly indicated herein. The terms "comprise", "include" and "have" are inclusive and therefore specify the presence of features, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components and / or combinations thereof. The method steps, processes and operations described herein should not be interpreted as necessarily requiring them to be performed in the particular order discussed or shown, unless specifically identified as an execution order. Additional or alternative steps may be adopted.

[0065] As used herein, the phrases "in one embodiment," "according to one embodiment," "in some embodiments," and the like generally refer to the fact that the particular feature, structure, or characteristic following the phrase may be included in at least one embodiment of the present disclosure. Thus, a particular feature, structure, or characteristic may be included in more than one embodiment of the present disclosure, such that these phrases do not necessarily refer to the same embodiment. As used herein, the terms "example," "exemplary," and the like are used to "serve as an example, instance, or illustration." Any implementation, aspect, or design described herein as "example" or "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations, aspects, or designs. Instead, the use of the terms "example," "exemplary," and the like is intended to present concepts in a concrete manner.

[0066] In the description of the embodiments of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0067] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, terms such as "first", "second" and other numerical terms do not imply an order or sequence when used herein unless expressly indicated above. Therefore, without departing from the teachings of the example embodiments, the first element, component, region, layer or section discussed above may be referred to as a second element, component, region, layer or section.

[0068] Spatially relative terms, such as "inside," "outside," "below," "beneath," "down," "above," "on," etc., may be used herein to describe the relationship of one element or feature to another element or feature as illustrated in the figures. In addition to the orientations depicted in the figures, spatially relative terms may be intended to encompass different orientations of the device in use or operation. For example, if the device in the figures is flipped, an element described as being "below" or "below" other elements or features will be oriented to be "above" the other elements or features. Thus, the example term "below" may encompass both above and below orientations. The device may be oriented otherwise (rotated 90 degrees or in other orientations), and the spatially relative descriptors used herein are interpreted accordingly.

[0069] In the above discussion, unless otherwise indicated, the terms "about," "approximately," "substantially," etc., when used to describe a numerical value, mean a variation of + / - 10% of the value.

[0070] With the above-described preferred embodiments of the present invention as a guide, and with reference to the above description, relevant personnel are fully capable of making various changes and modifications without departing from the technical scope of this invention. The technical scope of this invention is not limited to the contents of the specification and must be determined according to the scope of the claims.

Claims

1. A steel ball feeding device, comprising: A storage barrel (1) for storing steel balls (5), with at least one discharge hole (11) being provided at the bottom of the barrel; A material taking plate (2) is provided with a material receiving groove (21) on its surface facing the material storage barrel (1); A driver (3) connected to the reclaiming plate (2); Pick-and-place mechanism (4); The control module is electrically connected to the driver (3) and the pick-up and placement mechanism (4), and is configured to control the driver (3) to drive the pick-up plate (2) to move back and forth between the discharge hole (11) and the transfer position (41) to transfer the steel balls (5) in the storage barrel (1), and is also configured to control the pick-up and placement mechanism (4) to absorb the steel balls (5) in the material trough (21) at the transfer position (41) and place the absorbed steel balls (5) into the product; It is characterized in that a positioning component (22) is provided in the material holding trough (21), and the positioning component (22) is connected to the oiling mechanism (6); wherein The positioning assembly (22) is adapted to protrude the received steel balls (5) out of the trough (21) at the discharge hole (11) and the transfer position (41); During the process of the feeding plate (2) moving toward the transfer position (41), the positioning assembly (22) is pushed outward by the steel ball (5) so that the steel ball (5) is immersed in the material storage trough (21), and at the same time, the positioning assembly (22) squeezes the oiling mechanism (6) through the pushing action to spray lubricating oil on the steel ball (5), and the positioning assembly (22) rotates the steel ball (5) by pressing the steel ball (5) against the storage barrel (1) to evenly spread the lubricating oil; The depth of the material holding trough (21) is greater than the diameter of the steel ball (5), so that the steel ball (5) can be pushed open by the positioning assembly (22) and then immersed in the material holding trough (21); The positioning assembly (22) comprises: a plurality of positioning blocks (221), each of the positioning blocks (221) surrounding each other to form a positioning groove (222); wherein When the material trough (21) is located at the discharge hole (11) or the transfer position (41), the positioning groove (222) receives the steel ball (5) and protrudes out of the material trough (21); A plurality of guide shafts (223) are provided in the material holding trough (21); A guide groove (225) is provided on the positioning block (221), and the positioning block (221) is sleeved on the guide shaft (223) through the guide groove (225); The guide groove (225) is provided with a return spring (224) to bring the positioning blocks (221) together to make the steel ball (5) protrude from the material trough (21); The lubricating mechanism (6) is connected to the guide groove (225) and is suitable for replenishing lubricating oil into the guide groove (225); The positioning block (221) is provided with an oil filling port (226) communicating with the guide groove (225); The positioning block (221) is adapted to expand and squeeze the lubricating oil in the guide groove (225) outwards and spray it out through the oil filling port (226); An oil hole (228) is provided in the guide shaft (223); One end of the oil hole (228) is connected to the guide groove (225), and the other end is connected to the oiling mechanism (6); The bottom of the material trough (21) is provided with a plurality of oil drain holes (227), each of the oil drain holes (227) corresponding to each positioning block (221); wherein When the material trough (21) is located at the discharge hole (11) or the transfer position (41), each positioning block (221) blocks the corresponding oil drain hole (227).

2. The steel ball feeding device according to claim 1, characterized in that: The material taking plate (2) is inserted into a guide block (20); wherein The guide block (20) is in contact with the lower surface of the storage barrel (1), and a feeding hole (201) communicating with the discharge hole (11) is provided on the guide block (20); During the process of the picking plate (2) moving toward the transfer position (41), the positioning assembly (22) presses the steel ball (5) against the guide block (20) to rotate the steel ball (5).

3. A working method of the steel ball feeding device according to any one of claims 1-2, characterized in that: include: The control module controls the driver (3) to drive the material taking plate (2) to move back and forth between the material discharge hole (11) of the material storage barrel (1) and the material transfer position (41) of the pick-up and place mechanism (4) to transfer the steel balls (5) in the material storage barrel (1); The control module controls the pick-and-place mechanism (4) to absorb the steel balls (5) in the material trough (21) at the transfer position (41), and places the absorbed steel balls (5) into the product; The received steel ball (5) is protruded out of the trough (21) at the discharge hole (11) and the transfer position (41) by a positioning assembly (22) in the trough (21); The positioning assembly (22) is moved under pressure to cause the oiling mechanism (6) to spray lubricating oil onto the steel ball (5).

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