INSERTION AND EXTRACTION TOOL FOR ROTOR PIN OF PLASTER MIXER AND PLASTER MIXER WITH SUCH PIN
Patent Information
- Authority / Receiving Office
- MX · MX
- Patent Type
- Patents
- Current Assignee / Owner
- KNAUF GIPS KG
- Filing Date
- 2022-08-18
- Publication Date
- 2026-06-12
AI Technical Summary
Conventional gypsum board mixers face challenges in efficiently replacing worn-out rotor pins due to difficult access and time-consuming maintenance, leading to slurry buildup and poor quality products.
A gypsum mixer rotor pin with a cross hole near the top and a dedicated insertion and removal tool, allowing for easy replacement using a rod and driving tool, reducing downtime and extending pin lifespan through chrome plating.
Facilitates quick and efficient rotor pin replacement, minimizing maintenance disruptions and preventing slurry buildup, thereby improving production efficiency and product quality.
Smart Images
Figure MX434617B0
Abstract
Description
INSERTION AND EXTRACTION TOOL FOR ROTOR PIN OF PLASTER MIXER AND PLASTER MIXER WITH SUCH PIN BACKGROUND OF THE INVENTION The present invention relates generally to an apparatus used in the production of gypsum board panels, and more specifically to mixers used to generate the gypsum board suspension that ultimately becomes the core of the gypsum board panels. Gypsum board slurry mixers are well known in the art, and suitable examples are described in U.S. Patents Nos. 6,494,609; 6,059,44; and 3,459,620, all of which are incorporated by reference. Such mixers include a mixer housing within which a rotating agitator is mounted. The term agitator encompasses various forms, including an impeller, a disc, or some other equivalent structure. The mixer pins, or rotor pins, are fixed and supported by a lower portion of a cover as part of the mixer housing, and they also project upward and move with the agitator into the gypsum slurry. Variations in the positioning of the rotor pins are known, depending on the type of agitator and / or the mixer design. The rotor pins assist in mixing the Ref. 336984 suspension, a combination of water, ground stucco, and other additives known in the art, and generates shear forces within the mixer. Preferably, there are at least 9-12 pins in each mixer. Due to the abrasive working environment of the mixer agitator, the pins are frequently replaced due to wear, sometimes as often as once a month. In conventional mixers, replacing the mixer pins is time-consuming and disrupts the production cycle. If the mixer pins are not replaced promptly, unwanted slurry buildup occurs. In extreme cases, this buildup leads to premature setting of parts of the slurry, resulting in poor-quality drywall panels, as well as costly mixer cleaning and related maintenance. In a known drywall mixer, the problem of rotor pin replacement was identified. The pin was secured to the agitator by a threaded nozzle or stem coupled with a lock nut located in a depression in the agitator. Because the lock nut nearly filled the depression, access to the lock nut with conventional tools was difficult. Consequently, there is a need for an improved drywall mixer pin that is more easily replaceable to reduce the maintenance-related downtime experienced in conventional drywall mixers. SUMMARY OF THE INVENTION The aforementioned need is met or exceeded by the present combination of a plaster mixer rotor pin and an insertion / extraction tool. A key feature of the rotor pin is the placement of a transverse hole near the top of the pin. The transverse hole is configured to accommodate a rod, preferably sized to slide into the hole. Another feature of the present pin is that the placement of the rod in the hole allows the rotor pin insertion / extraction tool to selectively engage the rod by means of a groove located at one end of the tool. An opposite end of the tool has a non-circular receptacle that houses a drive tool.The drive tool, along with the rotor pin, rod, and insertion and extraction tool, is preferably used to replace rotor pins with relative ease and at a faster rate than available in conventional models, thus reducing downtime related to the maintenance of plasterboard mixers. Furthermore, the rotor pin is preferably chrome-plated, which extends its lifespan by at least ten times. As the chrome plating wears away due to the abrasive environment created by the suspension, the user is advised that it is time to replace the pin to prevent unwanted suspension buildup. More specifically, an apparatus for inserting and removing a mixer rotor pin includes at least one rotor pin with a body having a transverse hole, as well as a rod sized to slidably engage the transverse hole. The apparatus also includes a mixer rotor pin insertion and extraction tool having a tool body shaped to cover the rotor pin body. A lower portion of the tool has a groove for selectively engaging the aforementioned rod when the rod is inserted into the transverse hole, and an upper portion of the tool has a non-circular receptacle for housing a drive tool. In a preferred embodiment, the rotor pin body is cylindrical. The body is also preferably chrome-plated to improve its service life and to provide a user with a warning of its overall wear. However, the cross-hole is preferably left unchromed. Furthermore, in a preferred embodiment, the cross-hole is located near the top of each rotor pin, more preferably at a height of three-quarters of the rotor pin body height, measured from the bottom of the body. Additionally, it is preferred that, given a cylindrical rotor pin body, the diameter of the cross-hole be five-sixteenths of the body diameter, and that each opening of the cross-hole have a chamfered edge. A preferred embodiment of the apparatus also includes a threaded nozzle configured to attach the rotor pin to a gypsum suspension mixer. The threaded nozzle is preferably attached to the lower portion of the rotor pin body. Furthermore, the nozzle preferably has a diameter equal to two-thirds of the rotor pin body and a chamfered lower edge. It is also preferred that the present apparatus include a rod which, when inserted into the transverse hole, is of sufficient length to selectively engage the groove of the rotor pin insertion and extraction tool. A preferred rotor pin insertion and extraction tool has a hexagonal receptacle to accommodate a hex key drive tool. Once the tool is engaged with the rod, rotation of the tool facilitates rotation of the mixer pin, either to remove an existing pin or to tighten a replaced pin. In another embodiment, a mixer rotor pin for creating shear forces in the gypsum slurry includes a body with a transverse hole, the transverse hole sized to slide onto a rod, and a threaded nozzle attached to a lower portion of the body. Preferably, the rotor pin body is cylindrical. Furthermore, the transverse hole is preferably located near the top of the rotor pin, more precisely, at a height of three-quarters of the rotor pin body height, measured from the bottom of the body. The hole diameter is preferably five-sixteenths of the body diameter, and each opening of the transverse hole has a chamfered edge. A preferred embodiment of the mixer rotor pin also includes a threaded nozzle attached to the bottom of the rotor pin body for securing the rotor pin to a gypsum slurry mixer agitator. The threaded nozzle preferably has a diameter of two-thirds of the rotor pin body and a chamfered lower edge. In yet another embodiment, a mixer for formulating gypsum suspension includes a mixer housing that defines a space into which a powdered material and a quantity of water can be introduced to form the suspension; an agitator rotatably mounted in the housing to rotate in the space; and at least one rotor pin configured to mount on the agitator and generally projecting normally toward the agitator.Each rotor pin has a body with a transverse hole; each rotor pin is configured to accommodate a rod sized to slide into the transverse hole; and each rotor pin is configured to be engaged by a mixer rotor pin insertion and extraction tool having a tool body shaped to engage compatiblely with at least one rotor pin body, a lower body portion having a groove for selectively engaging the rod when inserting the rod into the transverse hole, and an opposite upper body portion having a non-circular receptacle for accommodating a drive tool. BRIEF DESCRIPTION OF THE FIGURES Figure 1A is a fragmentary schematic top plan view of a gypsum slurry mixer; Figure IB is a fragmentary side view of a gypsum suspension mixer agitator with a mixer rotor pin mounted on the agitator; Figure 2I is a side view of the present gypsum suspension mixer rotor pin; Figure 2B is a side view of a rod used with the present rotor pin; Figure 3 is a top view of the gypsum slurry mixer rotor pin shown in Figure 2A; Figure 4 is a side view of the present gypsum slurry mixer rotor pin insertion and extraction tool; Figure 5 is a top view of the gypsum slurry mixer rotor pin insertion and removal tool shown in Figure 4; and Figure 6 is a side view of the gypsum slurry mixer rotor pin insertion and removal tool, shown in Figure 4, attached to the mixer rotor pin, shown in Figure 2A. DETAILED DESCRIPTION OF THE INVENTION With reference to Figure 1A, a mixing apparatus for mixing and dispensing a suspension is generally designated 10 and includes a mixer 12 having a housing 14 configured to receive and mix the suspension. The housing 14 defines a mixing chamber 16, which is preferably cylindrical in shape, has a generally vertical axis 18, an upper radial wall 20, a lower radial wall 22, and an annular peripheral wall 24. An inlet 26 for calcined gypsum and an inlet 28 for water are both positioned in the upper radial wall 20, preferably near the vertical axis 18. It should be noted that the inlets 26 and 28 are connected to supply vessels for gypsum and water, respectively (not shown), so that the gypsum and water are supplied to the mixing chamber 16 by simple gravity feed. It is contemplated that the positioning of the inlets 26 and 28 may vary to suit the application.Also, as is known in the art, in addition to gypsum and water, other materials or additives commonly used in suspensions to prepare gypsum products (e.g., accelerators, retarders, fillers, starch, binders, strengtheners, etc.) are optionally supplied through these or other similarly positioned inlets. An agitator 30 is disposed in the mixing chamber 16. It has a generally vertical drive shaft 32 positioned concentrically with the vertical shaft 18 and extending through the upper radial wall 20. The shaft 32 is connected to a conventional drive source, such as a motor (not shown), to rotate the shaft at any speed suitable for agitating the agitator 30 to mix the contents of the mixing chamber 16. Speeds in the range of 275–300 rpm are common. This rotation directs the resulting aqueous suspension in a generally centrifugal direction, such as in an outward counterclockwise spiral. It should be appreciated that this representation of an agitator is relatively simplified and intended only to illustrate the basic principles of agitators commonly employed in gypsum suspension mixing chambers known in the art, some of which have been described above.Alternative agitator designs are being considered, including those that use pins, paddles, or rotating discs. An outlet 34, also called the mixer outlet, discharge gate, or slot, is provided in the peripheral wall 24 for discharging most of the well-mixed suspension into what is generally referred to herein as the mixer and dispenser 36. As is the case with conventional outlets, this outlet 34 is preferably rectangular in cross-section; however, other shapes are contemplated depending on the application. Furthermore, while it is contemplated that the specific configuration of the mixer 12 may vary, it is preferred that this mixer be of the centrifugal type commonly used in the manufacture of plasterboard, and also of the type in which the outlet 34 distributes the suspension tangentially into the housing 14. The mixing and dispensing apparatus 36 includes an elongated tube or conduit, preferably cylindrical 38, having a main inlet 39 connected to the mixer outlet 34, which receives the slurry, and an additive inlet 40, such as a nozzle, for introducing aqueous foam or other desired additives, such as retarders, accelerators, dispersants, starch, binders, and strength-enhancing products, such as polyphosphates, typically sodium trimetaphosphate, all of which are known in the drywall industry, after the slurry has been substantially mixed. It is desirable that when foam is the additive, it be uniformly mixed into the slurry, but not agitated excessively to the point of decomposition. Therefore, it is common to introduce the foam into the additive inlet 40 just downstream of, but near, the outlet 34 and the main inlet 39 to prolong the mixing time with the slurry.However, depending on the particular application, it is envisaged that the additive, such as foam, can be introduced in other places along the apparatus 36. With regard to Figures 1B-3, the present plaster mixer rotor pin is generally designated as 50 and has a preferably cylindrical body 52 with a transverse hole 54, an upper end 56, and an opposite lower end 58. Other shapes of the body 52 are contemplated depending on the application, including polygonal, asymmetrical, or irregular shapes. Preferably, a threaded nozzle 60 is attached to the lower end 58 of the body 52 for loosely attaching the body 52 to the stirrer 30. When attached to the stirrer 30, the body 52 preferably projects parallel to the axis of rotation 18 of the stirrer 30. In addition, the body 52 preferably projects normally toward an arm or main element 62 of the stirrer. The threaded nozzle 60 is preferably given a diameter d equal to 2 / 3 of a diameter D of the body 52 and a chamfered lower edge 64.The body 52 is preferably chrome-plated, while the transverse hole 54 and the threaded nozzle 60 are preferably left unchrome-plated. In a preferred embodiment, the transverse hole 54 is positioned at a height or length 1 located a of a total height or length L of the body 52, where 1 is measured from the upper end 56 of the body 52. Preferably, the diameter of the hole 54 is 5 / 16 of the diameter D of the body 52. Furthermore, the hole 54 is preferably provided with a pair of opposing openings, each opening having a chamfered edge 66 for the ideal accommodation of a rod, generally designated as 68. A rod diameter 68 is dimensioned to slidably engage with the hole 54, and a rod length is preferably dimensioned to sufficiently engage a mixer rotor pin insertion and extraction tool, generally designated as 70. With respect to Figures 4-6, the present gypsum mixer rotor pin insertion and extraction tool 70 has a tool body 72 sized for compatibility with the pin body 52, such that the tool body slides into the pin 50 (Figure 6). A lower portion 74 of the tool body 72 defines a groove 76, sized to selectively engage the rod 68 when the rod is inserted into the transverse hole 54. In the preferred embodiment, the groove 76 is sized to facilitate positioning the tool 70 over the rod 68 so that, as described in more detail below, rotating the tool exerts sufficient torque on the pin 50 to improve the removal of the agitator 30.More specifically, an open end 78 of the groove 76 is wider than an opposite vertex end 80, which is preferably arched to accommodate the rod diameter 68. The side walls 82 of the groove 76 taper from the open end 78 to the vertex end 80 and preferably form a general inverted V shape. Opposite the lower end 74 of the tool body 72 is an upper end 84 having a non-circular receptacle 86 configured to accommodate a driving tool (not shown). The tools contemplated include ratchet wrenches, Allen wrenches, or similar tools, as are well known in the art. It should be noted that the representation of the hexagonal receptacle 84 in Figure 5 represents a preferred embodiment; alternative shapes of non-circular receptacles, such as square, octagonal, and others, are contemplated. With reference specifically to Figure 6, when in use, the rotor pin insertion and extraction tool 70 is positioned in the pin body 52, so that the groove 76 engages the rod 68 located in the transverse hole 54. When a driving tool is engaged in the receptacle 84 and manipulated to create torque (turned clockwise or counterclockwise, depending on the desired action), the tool body 72 acting on the rod 68 axially rotates the pin 50. Referring again to Figures 1A and 2A2B, once pin 50 is fully engaged with arm 62, a shoulder 88 of pin 52 rests on the arm. Therefore, shoulder 88 facilitates the support of pin 50 on the shaker arm 62. Although a particular embodiment of the present plaster mixer rotor pin insertion and extraction tool has been described herein, those skilled in the art will appreciate that changes and modifications can be made to it without departing from the invention in its broader aspects and as indicated in the following claims. It is hereby stated that, as of this date, the best method known to the applicant for putting the aforementioned invention into practice is the one that is clear from the present description of the invention.
Claims
1. An apparatus for inserting and extracting a mixer rotor pin, characterized in that it comprises: at least one rotor pin having a body and a transverse hole; a rod dimensioned to slidably engage the transverse hole; and a mixer rotor pin insertion and extraction tool having a tool body shaped to be compatiblely engaged with the at least one rotor pin body, wherein a lower portion of the body has a groove for selectively engaging the rod when the rod is inserted into the transverse hole, and wherein an opposite upper portion of the body has a non-circular receptacle for housing a driving tool.
2. The apparatus according to claim 1, characterized in that each at least one rotor pin has a cylindrical body, wherein the body has a body diameter and wherein the transverse hole has a hole diameter 5 / 16 of the body diameter.
3. The apparatus according to claim 1, characterized in that each at least one rotor pin is chrome-plated in the body and the transverse hole is not chrome-plated.
4. The apparatus according to claim 1, characterized in that the transverse hole is placed at a height measured from a lower end that is the height of the body.
5. The apparatus according to claim 1, characterized in that the transverse hole has a pair of opposing openings, each of the openings having a chamfered edge.
6. The apparatus according to claim 1, characterized in that the rod, when inserted into the transverse hole, has a length sufficient to selectively engage the groove of the mixer rotor pin insertion and extraction tool.
7. The apparatus according to claim 1, characterized in that each of the at least one rotor pin has a threaded nozzle attached to the lower part of the body, and the threaded nozzle has a chamfered lower edge.
8. The apparatus according to claim 7, characterized in that the body has a body diameter, and the threaded nozzle has a nozzle diameter 2 / 3 of the body diameter.
9. The apparatus according to claim 1, characterized in that the mixer rotor pin insertion and extraction tool has a hexagonal receptacle for housing a hex key drive tool.
10. A mixer for formulating gypsum suspensions, characterized in that it comprises: a mixer housing defining a space into which a powdered material and a quantity of water can be introduced to form the suspension; an agitator rotatably mounted in the housing to rotate in the space; at least one rotor pin configured to be mounted on the agitator and generally projecting normally towards the agitator; wherein each at least one rotor pin has a body with a transverse hole; each rotor pin configured to accommodate a rod dimensioned to slidably engage the transverse hole;and each rotor pin configured to be engaged by means of a mixer rotor pin insertion and extraction tool having a tool body, shaped to be compatiblely engaged with at least one rotor pin body, wherein a lower portion of the body has a groove for selectively engaging the rod by inserting the rod into the 5 transverse hole, and wherein an opposite upper portion of the body has a non-circular receptacle for accommodating a driving tool.